Lifecycle of an Android Application

In most cases, every Android application runs in its own Linux process. This process is created for the application when some of its code needs to be run, and will remain running until it is no longer needed and the system needs to reclaim its memory for use by other applications.

An important and unusual feature of Android is that an application process's lifetime is not directly controlled by the application itself. Instead, it is determined by the system through a combination of the parts of the application that the system knows are running, how important these things are to the user, and how much overall memory is available in the system.

It is important that application developers understand how different application components (in particular Activity, Service, and IntentReceiver) impact the lifetime of the application's process. Not using these components correctly can result in the system killing the application's process while it is doing important work.

A common example of a process lifecycle bug is an IntentReceiver that starts a thread when it receives an Intent in its onReceiveIntent() method, and then returns from the function. Once it returns, the system considers that IntentReceiver to be no longer active, and thus its hosting process no longer needed (unless other application components are active in it). Thus, it may kill the process at any time to reclaim memory, terminating the spawned thread that is running in it. The solution to this problem is to start a Service from the IntentReceiver, so the system knows that there is still active work being done in the process.

To determine which processes should be killed when low on memory, Android places them into an "importance hierarchy" based on the components running in them and the state of those components. These are, in order of importance:

   1. A foreground process is one holding an Activity at the top of the screen that the user is interacting with (its onResume() method has been called) or an IntentReceiver that is currently running (its onReceiveIntent() method is executing). There will only ever be a few such processes in the system, and these will only be killed as a last resort if memory is so low that not even these processes can continue to run. Generally at this point the device has reached a memory paging state, so this action is required in order to keep the user interface responsive.

   2. A visible process is one holding an Activity that is visible to the user on-screen but not in the foreground (its onPause() method has been called). This may occur, for example, if the foreground activity has been displayed with a dialog appearance that allows the previous activity to be seen behind it. Such a process is considered extremely important and will not be killed unless doing so is required to keep all foreground processes running.

   3. A service process is one holding a Service that has been started with the startService() method. Though these processes are not directly visible to the user, they are generally doing things that the user cares about (such as background mp3 playback or background network data upload or download), so the system will always keep such processes running unless there is not enough memory to retain all foreground and visible process.

   4. A background process is one holding an Activity that is not currently visible to the user (its onStop() method has been called). These processes have no direct impact on the user experience. Provided they implement their activity lifecycle correctly (see Activity for more details), the system can kill such processes at any time to reclaim memory for one of the three previous processes types. Usually there are many of these processes running, so they are kept in an LRU list to ensure the process that was most recently seen by the user is the last to be killed when running low on memory.

   5.An empty process is one that doesn't hold any active application components. The only reason to keep such a process around is as a cache to improve startup time the next time a component of its application needs to run. As such, the system will often kill these processes in order to balance overall system resources between these empty cached processes and the underlying kernel caches.

When deciding how to classify a process, the system picks the most important level of all the components currently active in the process. See the Activity, Service, and IntentReceiver documentation for more detail on how each of these components contribute to the overall lifecycle of a process. The documentation for each of these classes describes in more detail how they impact the overall lifecycle of their application.

Andriod 2D Graphics - Drawing Pad Sample

In this aritcle shows how to use onDraw() method and create a simple drawing program. The only significant files are Draw activity and the DrawView. You should see a black screen and be able to draw on it with your finger.

This activity creates the DrawView and sets it as activity's main content. It also sets the borderless window.

MainActivity.java
public class MainActivity extends Activity {
    DrawView drawView;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        drawView = new DrawView(this);
        setContentView(drawView);
        drawView.requestFocus();
    }

    // DrawView is a view. It listens to mouse click events and draws a point at the point that it was clicked on.
   public class DrawView extends View implements OnTouchListener {
        List<Point> points = new ArrayList<Point>();
        Paint paint = new Paint();
        public DrawView(Context context) {
        super(context);
        setFocusable(true);
        setFocusableInTouchMode(true);
        this.setOnTouchListener(this);
        paint.setColor(Color.WHITE);
        paint.setAntiAlias(true);
        }

    @Override
    public void onDraw(Canvas canvas) {
        for (Point point : points) {
            canvas.drawCircle(point.x, point.y, 5, paint);
        }
    }

    public boolean onTouch(View view, MotionEvent event) {
        Point point = new Point();
        point.x = event.getX();
        point.y = event.getY();
        points.add(point);
        invalidate();
        return true;
    }
}
    class Point {
        float x, y;
        @Override
        public String toString() {
        return x + ", " + y;
        }
    }
}

Custom ContextMenu using PopupWindow Sample

Here we are creating a  custom contextmenu using PopupWindow in android. A simple PopUpWindow can be created using the following steps.
   1)A layout XML  which describes the View that will be rendered within a PopUpWindow  has to be created.
   2)Invoke the PopUpWindow by inflating the layout XML,  and assign appropriate  “parent view”  to  the pop-up.

Popup_example.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:padding="10dip" android:layout_width="fill_parent"
android:layout_height="wrap_content" >
    <TextView android:layout_width="fill_parent"
    android:layout_height="wrap_content" android:layout_marginTop="10dip" android:text="Test Pop-Up"/>
</LinearLayout>

Java Code:
    LayoutInflater inflater = (LayoutInflater)
    this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    PopupWindow pw = new PopupWindow(
    inflater.inflate(R.layout.popup_example, null, false),  100,  100,    true);
    // The code below assumes that the root container has an id called 'main'
    pw.showAtLocation(this.findViewById(R.id.main), Gravity.CENTER, 0, 0); 

How to Dismiss the PopUp Window?

Declare the necessary variables:

         private PopupWindow Popup;
       //how much time your popup window should appear
        private static final int POPUP_DISMISS_DELAY = 4000
       private DismissPopup mDismissPopup = new DismissPopup();


Class for dismissing the PopUp Window
Create a class which helps in dismissing the window automatically after the specified time:
class DismissPopup implements Runnable {
  public void run() {
      // Protect against null-pointer exceptions
      if (mPopup != null) {
          mPopup.dismiss();
      }
  }
}

Code Snippet:
Popup = new PopupWindow(this.getViewInflate()
                  .inflate(R.layout.main1,null,null),0,0);  
Popup.setOutsideTouchable(false);
Popup.setTouchInterceptor(new OnTouchListener() {

public boolean onTouch(View v, MotionEvent event) {
return false;
}});

Popup.showAtLocation(this.findViewById(R.id.main2),Gravity.BOTTOM, 20, 20);

youractivity.postDelayed(mDismissPopup, POPUP_DISMISS_DELAY);

2D graphics with Effects

In this article help us to set the different type of effect in the drawable.

Effects

Shadow Effect
This draws a shadow layer below the main layer, with the specified offset and color, and blur radius.


MaskFilterEffect
MaskFilter is the base class for object that perform transformations on an alpha-channel mask before drawing it. A subclass of MaskFilter may be installed into a Paint. Blur and emboss are implemented as subclasses of MaskFilter.

Sample Implementation:
Blur Filter
paint.setMaskFilter(new BlurMaskFilter(15, Blur.INNER));
paint.setMaskFilter(new BlurMaskFilter(15, Blur.OUTER));
paint.setMaskFilter(new BlurMaskFilter(15, Blur.SOLID));
paint.setMaskFilter(new BlurMaskFilter(15, Blur.NORMAL));

Emboss Filter
paint.setMaskFilter(new EmbossMaskFilter(new float[] { 1, 1, 1 },0.4f, 10, 8.2f));

Shader Effect
Shader is the based class for objects that return horizontal spans of colors during drawing. A subclass of Shader is installed in a Paint calling paint.setShader(shader). After that any object (other than a bitmap) that is drawn with that paint will get its color(s) from the shader.

Shader Sample Implementation:
LinearGradient
paint.setShader(new LinearGradient(8f, 80f, 30f, 20f, Color.RED,Color.WHITE, Shader.TileMode.MIRROR));

RadialGradient
paint.setShader(new RadialGradient(8f, 80f, 90f, Color.RED,Color.WHITE, Shader.TileMode.MIRROR));

SweepGradient
paint.setShader(new SweepGradient(80, 80, Color.RED, Color.WHITE));



Sample Apps
Layout : main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent">

<LinearLayout android:id="@+id/ImageView01" android:layout_height="150dip" android:layout_width="150dip"
android:layout_gravity="center"></LinearLayout>
<LinearLayout android:id="@+id/LinearLayout01" android:layout_width="wrap_content" android:layout_height="wrap_content"
android:layout_gravity="center">
<Button android:text="Draw Cicle" android:id="@+id/circle"
android:layout_height="wrap_content" android:layout_gravity="center"
android:layout_width="85dip" android:gravity="center"></Button>
<Button android:text="Anti Alias" android:id="@+id/antialias"
android:layout_height="wrap_content" android:layout_gravity="center"
android:layout_width="85dip" android:gravity="center"></Button>
<Button android:text="Shadow" android:id="@+id/shadow"
android:layout_height="wrap_content" android:layout_gravity="center"
android:layout_width="85dip" android:gravity="center"></Button>
</LinearLayout>

<LinearLayout android:id="@+id/LinearLayout01"
android:layout_width="wrap_content" android:layout_height="wrap_content"
android:layout_gravity="center">
<Button android:text="Blur Effect - 1" android:id="@+id/blur1"
android:layout_height="wrap_content" android:layout_gravity="center"
android:layout_width="85dip" android:gravity="center"></Button>
<Button android:text="Blur Effect - 2" android:id="@+id/blur2"
android:layout_height="wrap_content" android:layout_gravity="center"
android:layout_width="85dip" android:gravity="center"></Button>
<Button android:text="Blur Effect - 3" android:id="@+id/blur3"
android:layout_height="wrap_content" android:layout_gravity="center"
android:layout_width="85dip" android:gravity="center"></Button>
</LinearLayout>

<LinearLayout android:id="@+id/LinearLayout01"
android:layout_width="wrap_content" android:layout_height="wrap_content"
android:layout_gravity="center">
<Button android:text="Blur Effect - 4" android:id="@+id/blur4"
android:layout_height="wrap_content" android:layout_gravity="center"
android:layout_width="85dip" android:gravity="center"></Button>
<Button android:text="Emboss" android:id="@+id/emboss"
android:layout_height="wrap_content" android:layout_gravity="center"
android:layout_width="85dip" android:gravity="center"></Button>
</LinearLayout>

<LinearLayout android:id="@+id/LinearLayout01"
android:layout_width="wrap_content" android:layout_height="wrap_content"
android:layout_gravity="center">
<Button android:text="Sweep" android:id="@+id/sweep"
android:layout_height="wrap_content" android:layout_gravity="center"
android:layout_width="85dip" android:gravity="center"></Button>
<Button android:text="Linear" android:id="@+id/linear"
android:layout_height="wrap_content" android:layout_gravity="center"
android:layout_width="85dip" android:gravity="center"></Button>
<Button android:text="Radial" android:id="@+id/radial"
android:layout_height="wrap_content" android:layout_gravity="center"
android:layout_width="85dip" android:gravity="center"></Button>
</LinearLayout>
</LinearLayout>


MainActivity.java

public class MainActivity extends Activity implements OnClickListener {

LinearLayout imageView;
Button circle, antialias, shadow, blur1, blur2, blur3, blur4, emboss,
sweep, radial, linear;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
imageView = (LinearLayout) findViewById(R.id.ImageView01);
circle = (Button) findViewById(R.id.circle);
antialias = (Button) findViewById(R.id.antialias);
shadow = (Button) findViewById(R.id.shadow);
blur1 = (Button) findViewById(R.id.blur1);
blur2 = (Button) findViewById(R.id.blur2);
blur3 = (Button) findViewById(R.id.blur3);
blur4 = (Button) findViewById(R.id.blur4);

emboss = (Button) findViewById(R.id.emboss);
sweep = (Button) findViewById(R.id.sweep);
linear = (Button) findViewById(R.id.linear);
radial = (Button) findViewById(R.id.radial);

circle.setOnClickListener(this);
antialias.setOnClickListener(this);
shadow.setOnClickListener(this);
blur1.setOnClickListener(this);
blur2.setOnClickListener(this);
blur3.setOnClickListener(this);
blur4.setOnClickListener(this);
emboss.setOnClickListener(this);
sweep.setOnClickListener(this);
linear.setOnClickListener(this);
radial.setOnClickListener(this);

}

@Override
public void onClick(View v) {
imageView.removeAllViews();
switch (v.getId()) {
case R.id.circle:
imageView.addView(new DrawView(MainActivity.this));
break;
case R.id.antialias:
imageView.addView(new DrawView(MainActivity.this).getAntiAlias());
break;
case R.id.shadow:
imageView
.addView(new DrawView(MainActivity.this).getShadowEffect());
break;
case R.id.blur1:
imageView.addView(new DrawView(MainActivity.this)
.getBlurMaskFitler(1));
break;
case R.id.blur2:
imageView.addView(new DrawView(MainActivity.this)
.getBlurMaskFitler(2));
break;
case R.id.blur3:
imageView.addView(new DrawView(MainActivity.this)
.getBlurMaskFitler(3));
break;

case R.id.blur4:
imageView.addView(new DrawView(MainActivity.this)
.getBlurMaskFitler(4));
break;
case R.id.emboss:
imageView.addView(new DrawView(MainActivity.this)
.getEmbossMaskFilter());
break;
case R.id.sweep:
imageView.addView(new DrawView(MainActivity.this)
.getSweepShaderEffect());
break;
case R.id.linear:
imageView.addView(new DrawView(MainActivity.this)
.getLinearShaderEffect());
break;
case R.id.radial:
imageView.addView(new DrawView(MainActivity.this)
.getRadialShaderEffect());
break;

}

}

public class DrawView extends View {
Paint paint = new Paint();
Context c;
final float xPos = 80, yPos = 80, radius = 40;

public DrawView(Context context) {
super(context);
c = context;
paint.setColor(Color.WHITE);
invalidate();
}

private View getAntiAlias() {

paint.setAntiAlias(true);
return this;
}

private View getShadowEffect() {
paint.setAntiAlias(true);
paint.setShadowLayer(10, 10, 5, Color.RED);
return this;
}

private View getBlurMaskFitler(int type) {
invalidate();
paint.setAntiAlias(true);
switch (type) {
case 1:
paint.setMaskFilter(new BlurMaskFilter(15, Blur.INNER));
break;
case 2:
paint.setMaskFilter(new BlurMaskFilter(15, Blur.OUTER));
break;
case 3:
paint.setMaskFilter(new BlurMaskFilter(15, Blur.SOLID));
break;
case 4:
paint.setMaskFilter(new BlurMaskFilter(15, Blur.NORMAL));
break;
}
return this;
}

private View getEmbossMaskFilter() {
paint.setAntiAlias(true);
paint.setMaskFilter(new EmbossMaskFilter(new float[] { 1, 1, 1 },
0.4f, 10, 8.2f));
return this;
}

private View getSweepShaderEffect() {
paint.setAntiAlias(true);
paint.setShader(new SweepGradient(80, 80, Color.RED, Color.WHITE));
return this;
}

private View getRadialShaderEffect() {
paint.setAntiAlias(true);
paint.setShader(new RadialGradient(8f, 80f, 90f, Color.RED,
Color.WHITE, Shader.TileMode.MIRROR));
return this;
}

private View getLinearShaderEffect() {
paint.setAntiAlias(true);
paint.setShader(new LinearGradient(8f, 80f, 30f, 20f, Color.RED,
Color.WHITE, Shader.TileMode.MIRROR));
return this;
}

@Override
public void onDraw(Canvas canvas) {
canvas.drawCircle(xPos, yPos, radius, paint);
}
}
}

Android 2D Graphics Example

This example shows how to use onDraw() method and create a simple drawing program. The only significant files are Draw activity and the DrawView.

MainActivity.java
public class MainActivity extends Activity { 
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);      
        DrawView drawView = new DrawView(this);
        setContentView(drawView);
        drawView.requestFocus();
    }
}


public class DrawView extends View {
    Paint paint = new Paint();
    Context c;
    public DrawView(Context context) {
        super(context);
        c= context;    
        paint.setColor(Color.WHITE);
        paint.setAntiAlias(true);
    }

    @Override
   public void onDraw(Canvas canvas) {
            canvas.drawCircle(100, 100, 50, paint);
    }
}
}

Sample Handler Implementation

Handler is a verry useful and powerful component in Android. Some special features of Handler are,

     If handler is created without any parameter, then it will be created in the same thread itself.
     We can pass data to handler using message

I have created the below sample application, which is using handler efficiently. Increment the count for one second.

So if we need to create a seperate thread for handler, first we need to create a thread and create the handler inside it.

MainActivity
public class MainActivity extends Activity {
    TextView tv;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        tv = (TextView) findViewById(R.id.TextView01);
        new Thread() {
            public void run() {
                int i = 0;
                while (i <= 100) {
                    try {
                        sleep(1000);
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                    messageHandler.sendMessage(Message
                            .obtain(messageHandler, i));
                    i++;
                }
            }
        }.start();
    }
    private Handler messageHandler = new Handler() {
        public void handleMessage(Message msg) {
            tv.setText(msg.what + "");
        }
    };
}

Main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="fill_parent"
    android:layout_height="fill_parent">
<TextView android:text="@+id/TextView01" android:id="@+id/TextView01"
    android:layout_width="wrap_content" android:layout_height="wrap_content"
    android:textSize="25dip" android:layout_gravity="center"
    android:layout_marginTop="150dip"></TextView>
</LinearLayout>

Sample Rating Bar Implementation

A RatingBar is an extension of SeekBar and ProgressBar that shows a rating in stars.

The user can touch/drag or use arrow keys to set the rating when using the default size RatingBar.

The smaller RatingBar style and
the larger indicator-only style do not support user interaction and should only be used as indicators.


larger indicator-only    -    style="?android:attr/ratingBarStyleIndicator"
smaller RatingBar     -    style="?android:attr/ratingBarStyleSmall"
Default            -    style="?android:attr/ratingBarStyle"

Create a Circle in Andrind

In this Ariticle helps to create a circle in andriod using

Create a Customized View Class
public class Ball extends View {}

Override the onDraw()
protected void onDraw(Canvas canvas) { }

Create Paint Object for draw the circle
mPaints1 = new Paint();
        mPaints2 = new Paint();
        mPaints1.setAntiAlias(true);
        mPaints1.setStyle(Paint.Style.FILL);

        mPaints2 = new Paint(mPaints1);
        mPaints2.setColor(Color.BLUE);
        mBigOval = new RectF(40, 10, 280, 250);

Draw Circle using drawArc
canvas.drawArc(oval, mStart, mSweep, useCenter, paint);


SourceCode

public class Ball extends View {

    private Paint mPaints2;
    private Paint mPaints1;
    private RectF mBigOval;
    private float mStart, mSweep;
    private int mBigIndex;

    public Ball(Context context) {
        super(context);

        mPaints1 = new Paint();
        mPaints2 = new Paint();
        mPaints1.setAntiAlias(true);
        mPaints1.setStyle(Paint.Style.FILL);

        mPaints2 = new Paint(mPaints1);
        mPaints2.setColor(Color.BLUE);
        mBigOval = new RectF(40, 10, 280, 250);
    }

    private void drawArcs(Canvas canvas, RectF oval, boolean useCenter,
            Paint paint) {
        canvas.drawArc(oval, mStart, mSweep, useCenter, paint);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        canvas.drawColor(Color.WHITE);
        drawArcs(canvas, mBigOval, true, mPaints2);
        mSweep += 2;
        if (mSweep > 360) {
            mStart += 10;
            if (mStart >= 360) {
                mStart -= 360;
            }
            mBigIndex = (mBigIndex + 1);
        }
        invalidate();
    }
}

Steps to create Andriod Widget

In this article will help us to create customized Widget.

1. Create a Layout for Widget
2. Create Widget Class
3. Adding the Widget Provider Info Metadata
4. Register the Widget in Androidmanifest.xml
5. Add the Widget in your homepage


Create a Layout for Widget
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="fill_parent"
    android:layout_height="fill_parent" android:background="@drawable/widget_bg">
    <Button android:text="Click" android:id="@+id/Button01"
        android:layout_width="wrap_content" android:layout_height="wrap_content"></Button>

    <TextView android:id="@+id/text" android:layout_width="fill_parent"
        android:layout_height="fill_parent" android:text="@string/hello"
        android:gravity="center" android:textColor="@android:color/black" />
</LinearLayout>

Create Widget Class
public class Widget extends AppWidgetProvider {
    private SimpleDateFormat formatter = new SimpleDateFormat(
            "EEE, d MMM yyyy\nHH:mm:ss.SSS");

    @Override
    public void onUpdate(Context context, AppWidgetManager appWidgetManager,
            int[] appWidgetIds) {
       
        String now = formatter.format(new Date());

        Intent intent = new Intent(context, MainActivity.class);
        PendingIntent pendingIntent = PendingIntent.getActivity(context, 0,intent, 0);

        RemoteViews updateViews = new RemoteViews(context.getPackageName(),R.layout.main);
        updateViews.setTextViewText(R.id.text, now);
        appWidgetManager.updateAppWidget(appWidgetIds, updateViews);

       
        RemoteViews views = new RemoteViews(context.getPackageName(),R.layout.main);
        views.setOnClickPendingIntent(R.id.Button01, pendingIntent);
        appWidgetManager.updateAppWidget(appWidgetIds, views);

        super.onUpdate(context, appWidgetManager, appWidgetIds);

    }
}

Adding the Widget Provider Info Metadata

    <?xml version="1.0" encoding="utf-8"?>
    <appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
        android:minWidth="166dip" android:minHeight="72dip" android:updatePeriodMillis="60000" android:initialLayout="@layout/main" />


Register the Widget in Androidmanifest.xml

    <receiver android:label="@string/widget_name" android:name=".Widget">       
        <intent-filter>
            <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
        </intent-filter>       
        <meta-data android:name="android.appwidget.provider" android:resource="@xml/widget" />       
    </receiver>

Add the Widget in your homepage
    Click Menu -> Add -> Widget -> YOUR WIDGET

Andriond Interview Question -1

Brief about the Android?
Andriod is a Operating System for device
It was initially developed by Android Inc., a firm later purchased by Google, and lately by the Open Handset Alliance.
It allows developers to write managed code in the Java language, controlling the device via Google-developed Java libraries.

Architecture of Android :
1. Linux Kernal [ 2.6 Kernal - security, memory management, process management, network stack, and driver model]
2. Native Libraries [SQLite, WEBKit, OpenGL,..]
3. Runtime + Dalvik VM [.dex format, Lightweight VM, Efficient Dalvik Bytecode]
4. Application Framework [Activity Manager, Content Manager, Location Manager, ]
5. Application [ System Apps and Your Apps]

Refer : http://about-android.blogspot.com/2009/11/architecture-of-android-1.html


What are the basic Components in Android?
Activities - An activity presents a visual user interface for one focused endeavor the user can undertake.
Services - A service doesn't have a visual user interface, but rather runs in the background for an indefinite period of time.
Broadcast receivers - A broadcast receiver is a component that does nothing but receive and react to broadcast announcements.
Content providers - A content provider makes a specific set of the application's data available to other applications.

http://about-android.blogspot.com/2009/11/application-fundamentals.html



what are the versions are avilable in android?
Version : 1.5 - Cupecake
Linux Version : 2.6.27
Offical release On : April 30th 2009
Main Feature :
* Ability to record and watch videos with the camcorder mode
* Uploading videos to YouTube and pictures to Picasa directly from the phone
* A new soft keyboard with an "Autocomplete" feature
* Bluetooth A2DP support and ability to automatically connect to a Bluetooth headset within a certain distance
* New widgets and folders that can populate the Home screens
* Animations between screens
* Expanded ability of Copy and paste to include web pages

Version : 1.6 - Donut
Linux Version : 2.6.29
Offical release On : April 30th 2009
Main Features :
* An improved Android Market experience.
* An integrated camera, camcorder, and gallery interface.
* Gallery now enables users to select multiple photos for deletion.
* Updated Voice Search, with faster response and deeper integration with native applications, including the ability to dial contacts.
* Updated search experience to allow searching bookmarks, history, contacts, and the web from the home screen.
* Updated Technology support for CDMA/EVDO, 802.1x, VPN, Gestures, and a Text-to-speech engine.
* Support for WVGA resolutions.
* Speed improvements for searching & the camera.[35]

Version : 2.0 & 2.1- Eclair
Linux Version : 2.6.29
Offical release On : October 26th 2009
Main Features :
* Optimized hardware speed
* Support for more screen sizes and resolutions
* Revamped UI
* New browser UI and HTML5 support
* New contact lists
* Better white/black ratio for backgrounds
* Improved Google Maps 3.1.2
* Microsoft Exchange support
* Built in flash support for Camera
* Digital Zoom
* MotionEvent class enhanced to track multi-touch events[41]
* Improved virtual keyboard
* Bluetooth 2.1
* Live Wallpapers

what is the folder structure of android?
1. src - It contain the java code
2. Resource - It contain the all resource with different floder
drawable - Icon
raw - Sounds
menu - Menu
values - Project Properties
layout - User interface Screens
3. gen - It contains the R.java file. You could not edit R.java manually. This have been generated automatically by understanding resource files etc.
4. AndroidManifest -It contains the Project properties
5. Android lib.

Refer :
http://about-android.blogspot.com/2009/11/application-fundamentals.html

what are the api available in the Android?
Activity Manager, WindowManager, Location Manager, View System, Notification Manager, Telephonic Manager, Package Manager,
Resource Manager,

Create Dynamic View Group

In this Aricle help us to create a dynamic view group.

public class MainActivity extends Activity {
    Button btn, btn1;
    LayoutInflater linflater;
    LinearLayout l;
    static int pos = 0;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        btn = (Button) findViewById(R.id.Button01);
        btn1 = (Button) findViewById(R.id.Button02);
        l = (LinearLayout) findViewById(R.id.LinearLayout01);
        linflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        btn.setOnClickListener(new myListener());
        btn1.setOnClickListener(new myListener1());
    }

    class myListener implements View.OnClickListener {
        @Override
        public void onClick(View v) {
            View myView = linflater.inflate(R.layout.dynamicoption, null);
            myView.setId(pos);
            pos++;
            l.addView(myView);
        }
    }

    class myListener1 implements View.OnClickListener {
        @Override
        public void onClick(View v) {
            if (pos != 0) {
                pos--;
                View myView = l.findViewById(pos);
                l.removeView(myView);
            }
        }
    }
}

main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent" android:layout_height="fill_parent"
    android:orientation="horizontal">

    <Button android:id="@+id/Button01" android:background="@drawable/plus"
        android:layout_height="45dip" android:layout_width="45dip"></Button>

    <Button android:id="@+id/Button02" android:background="@drawable/minus"
        android:layout_height="45dip" android:layout_width="45dip"></Button>

    <LinearLayout android:id="@+id/LinearLayout01"
        android:layout_width="wrap_content" android:layout_height="wrap_content"
        android:orientation="vertical"></LinearLayout>
</LinearLayout>

dynamicoption.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content" android:layout_height="wrap_content"
    android:orientation="horizontal">
    <EditText android:text="@+id/EditText01" android:id="@+id/EditText01"
        android:layout_width="wrap_content" android:layout_height="wrap_content"></EditText>
    <Button android:text="@+id/Button01" android:id="@+id/Button01"
        android:layout_width="wrap_content" android:layout_height="wrap_content"></Button>
</LinearLayout>

Icons
http://jmez.net/el/images/Minus.png
http://www.workingwithrails.com/images/plus.png?1213632569

Create Cutomized Color Picker in android

Code snippet for customized color picker

1. Create a Customized Color picker dialog box
2. Call the ColorPicker Dialog



Create a Customized Color picker dialog box

copy the below code and place into your package.

public class ColorPickerDialog extends Dialog {

    public interface OnColorChangedListener {
        void colorChanged(int color);
    }

    private final OnColorChangedListener mListener;
    private final int mInitialColor;

    private static class ColorPickerView extends View {
        private final Paint mPaint;
        private final Paint mCenterPaint;
        private final int[] mColors;
        private final OnColorChangedListener mListener;

        ColorPickerView(Context c, OnColorChangedListener l, int color) {
            super(c);
            mListener = l;
            mColors = new int[] { 0xFFFF0000, 0xFFFF00FF, 0xFF0000FF,
                    0xFF00FFFF, 0xFF00FF00, 0xFFFFFF00, 0xFFFF0000 };
            Shader s = new SweepGradient(0, 0, mColors, null);

            mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
            mPaint.setShader(s);
            mPaint.setStyle(Paint.Style.STROKE);
            mPaint.setStrokeWidth(32);

            mCenterPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
            mCenterPaint.setColor(color);
            mCenterPaint.setStrokeWidth(5);
        }

        private boolean mTrackingCenter;
        private boolean mHighlightCenter;

        @Override
        protected void onDraw(Canvas canvas) {
            float r = CENTER_X - mPaint.getStrokeWidth() * 0.5f;

            canvas.translate(CENTER_X, CENTER_X);

            canvas.drawOval(new RectF(-r, -r, r, r), mPaint);
            canvas.drawCircle(0, 0, CENTER_RADIUS, mCenterPaint);

            if (mTrackingCenter) {
                int c = mCenterPaint.getColor();
                mCenterPaint.setStyle(Paint.Style.STROKE);

                if (mHighlightCenter) {
                    mCenterPaint.setAlpha(0xFF);
                } else {
                    mCenterPaint.setAlpha(0x80);
                }
                canvas.drawCircle(0, 0, CENTER_RADIUS
                        + mCenterPaint.getStrokeWidth(), mCenterPaint);

                mCenterPaint.setStyle(Paint.Style.FILL);
                mCenterPaint.setColor(c);
            }
        }

        @Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
            setMeasuredDimension(CENTER_X * 2, CENTER_Y * 2);
        }

        private static final int CENTER_X = 100;
        private static final int CENTER_Y = 100;
        private static final int CENTER_RADIUS = 32;

        private int floatToByte(float x) {
            int n = java.lang.Math.round(x);
            return n;
        }

        private int pinToByte(int n) {
            if (n < 0) {
                n = 0;
            } else if (n > 255) {
                n = 255;
            }
            return n;
        }

        private int ave(int s, int d, float p) {
            return s + java.lang.Math.round(p * (d - s));
        }

        private int interpColor(int colors[], float unit) {
            if (unit <= 0)
                return colors[0];
            if (unit >= 1)
                return colors[colors.length - 1];

            float p = unit * (colors.length - 1);
            int i = (int) p;
            p -= i;

            // now p is just the fractional part [0...1) and i is the index
            int c0 = colors[i];
            int c1 = colors[i + 1];
            int a = ave(Color.alpha(c0), Color.alpha(c1), p);
            int r = ave(Color.red(c0), Color.red(c1), p);
            int g = ave(Color.green(c0), Color.green(c1), p);
            int b = ave(Color.blue(c0), Color.blue(c1), p);

            return Color.argb(a, r, g, b);
        }

        private int rotateColor(int color, float rad) {
            float deg = rad * 180 / 3.1415927f;
            int r = Color.red(color);
            int g = Color.green(color);
            int b = Color.blue(color);

            ColorMatrix cm = new ColorMatrix();
            ColorMatrix tmp = new ColorMatrix();

            cm.setRGB2YUV();
            tmp.setRotate(0, deg);
            cm.postConcat(tmp);
            tmp.setYUV2RGB();
            cm.postConcat(tmp);

            final float[] a = cm.getArray();

            int ir = floatToByte(a[0] * r + a[1] * g + a[2] * b);
            int ig = floatToByte(a[5] * r + a[6] * g + a[7] * b);
            int ib = floatToByte(a[10] * r + a[11] * g + a[12] * b);

            return Color.argb(Color.alpha(color), pinToByte(ir), pinToByte(ig),
                    pinToByte(ib));
        }

        private static final float PI = 3.1415926f;

        @Override
        public boolean onTouchEvent(MotionEvent event) {
            float x = event.getX() - CENTER_X;
            float y = event.getY() - CENTER_Y;
            boolean inCenter = java.lang.Math.sqrt(x * x + y * y) <= CENTER_RADIUS;

            switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                mTrackingCenter = inCenter;
                if (inCenter) {
                    mHighlightCenter = true;
                    invalidate();
                    break;
                }
            case MotionEvent.ACTION_MOVE:
                if (mTrackingCenter) {
                    if (mHighlightCenter != inCenter) {
                        mHighlightCenter = inCenter;
                        invalidate();
                    }
                } else {
                    float angle = (float) java.lang.Math.atan2(y, x);
                    // need to turn angle [-PI ... PI] into unit [0....1]
                    float unit = angle / (2 * PI);
                    if (unit < 0) {
                        unit += 1;
                    }
                    mCenterPaint.setColor(interpColor(mColors, unit));
                    invalidate();
                }
                break;
            case MotionEvent.ACTION_UP:
                if (mTrackingCenter) {
                    if (inCenter) {
                        mListener.colorChanged(mCenterPaint.getColor());
                    }
                    mTrackingCenter = false; // so we draw w/o halo
                    invalidate();
                }
                break;
            }
            return true;
        }
    }

    public ColorPickerDialog(Context context, OnColorChangedListener listener,
            int initialColor) {
        super(context);

        mListener = listener;
        mInitialColor = initialColor;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        OnColorChangedListener l = new OnColorChangedListener() {
            public void colorChanged(int color) {
                mListener.colorChanged(color);
                dismiss();
            }
        };

        LinearLayout layout = new LinearLayout(getContext());
        layout.setOrientation(LinearLayout.VERTICAL);
        layout.setGravity(Gravity.CENTER);
        layout.setPadding(10, 10, 10, 10);
        layout.addView(new ColorPickerView(getContext(), l, mInitialColor),
                new LinearLayout.LayoutParams(
                        LinearLayout.LayoutParams.WRAP_CONTENT,
                        LinearLayout.LayoutParams.WRAP_CONTENT));

        setContentView(layout);
        setTitle("Pick a Color");
    }
}


Call the ColorPicker Dialog
public class MainActivity extends Activity implements
        ColorPickerDialog.OnColorChangedListener {
    /** Called when the activity is first created. */
    private static final String BRIGHTNESS_PREFERENCE_KEY = "brightness";
    private static final String COLOR_PREFERENCE_KEY = "color";
    TextView tv;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        tv = (TextView) findViewById(R.id.TextView01);

        Button btn = (Button) findViewById(R.id.Button01);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int color = PreferenceManager.getDefaultSharedPreferences(
                        MainActivity.this).getInt(COLOR_PREFERENCE_KEY,
                        Color.WHITE);
                new ColorPickerDialog(MainActivity.this, MainActivity.this,
                        color).show();
            }
        });

    }

    @Override
    public void colorChanged(int color) {
        PreferenceManager.getDefaultSharedPreferences(this).edit().putInt(
                COLOR_PREFERENCE_KEY, color).commit();
        tv.setTextColor(color);

    }

}


main layout

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="fill_parent"
    android:layout_height="fill_parent" android:id="@+id/mainview">
    <Button android:text="Select Color" android:id="@+id/Button01"
        android:layout_width="wrap_content" android:layout_height="wrap_content"></Button>
    <TextView android:text="@+id/TextView01" android:id="@+id/TextView01"
        android:layout_width="wrap_content" android:layout_height="wrap_content"></TextView>
</LinearLayout>

Sample Apps to Control Screen Brightness

This will help us to create a brightness controller in andriod.

1. Create a Layout with seekbar
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="fill_parent"
    android:layout_height="fill_parent">


    <Button android:text="Show Brightness Panel" android:id="@+id/Button01"
        android:layout_width="wrap_content" android:layout_height="wrap_content"></Button>


    <LinearLayout android:id="@+id/panel" android:orientation="vertical"
        android:layout_width="fill_parent" android:layout_height="wrap_content"
        android:layout_alignParentBottom="true" android:paddingTop="10dip"
        android:paddingBottom="30dip" android:paddingLeft="20dip"
        android:paddingRight="20dip" android:gravity="center_horizontal"
        android:visibility="gone">

        <TextView android:text="Brightness Level"
            android:layout_width="fill_parent" android:layout_height="wrap_content"
            android:gravity="center" android:textAppearance="?android:attr/textAppearanceLarge" />

        <SeekBar android:id="@+id/seek" android:layout_width="fill_parent"
            android:layout_height="wrap_content" android:max="100"
            android:progress="100" />

    </LinearLayout>

</LinearLayout>

2. Create an activity to control the brightness
public class MainActivity extends Activity {
    /** Called when the activity is first created. */
    private static final String BRIGHTNESS_PREFERENCE_KEY = "brightness";
    private View brightnessPanel;
    private SeekBar brightnessControl;
    private int brightness = 50;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        brightnessPanel = findViewById(R.id.panel);
        brightnessControl = (SeekBar) findViewById(R.id.seek);

        Button btn = (Button) findViewById(R.id.Button01);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                showBrightnessPanel();

            }
        });

        brightnessControl
                .setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
                    public void onProgressChanged(SeekBar seekBar,
                            int progress, boolean fromUser) {
                        setBrightness(progress);
                    }

                    public void onStartTrackingTouch(SeekBar seekBar) {
                    }

                    public void onStopTrackingTouch(SeekBar seekBar) {
                        hideBrightnessPanel();
                    }
                });
    }

    private void showBrightnessPanel() {
        Animation animation = AnimationUtils.loadAnimation(this,
                android.R.anim.slide_in_left);
        brightnessControl.setProgress(this.brightness);
        brightnessPanel.setVisibility(View.VISIBLE);
        brightnessPanel.startAnimation(animation);
    }

    private void setBrightness(int value) {
        if (value < 10) {
            value = 10;
        } else if (value > 100) {
            value = 100;
        }
        brightness = value;
        WindowManager.LayoutParams lp = getWindow().getAttributes();
        lp.screenBrightness = (float) value / 100;       
        lp.flags |= WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON;
        getWindow().setAttributes(lp);
    }

    private void hideBrightnessPanel() {
        Animation animation = AnimationUtils.loadAnimation(MainActivity.this,
                android.R.anim.slide_out_right);
        brightnessPanel.startAnimation(animation);
        brightnessPanel.setVisibility(View.GONE);
        PreferenceManager.getDefaultSharedPreferences(this).edit().putInt(
                BRIGHTNESS_PREFERENCE_KEY, brightnessControl.getProgress())
                .commit();
    }

}

Create a Apps to Show Digital Time in Android

this blog helps to create a simple digital clock in andriod.

Create a Layout.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="fill_parent"
    android:layout_height="fill_parent">

    <TextView android:id="@+id/countdown" android:layout_width="320dip"
        android:layout_height="120dip" android:text="00:00:00"
        android:textSize="15pt" android:textColor="#00C2FF"
        android:layout_centerInParent="true" />
</RelativeLayout>


Create Activty Class for show the Time

public class MainActivity extends Activity {
    private TextView countdown;
    private Timer timer;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        TextView countdown = (TextView) findViewById(R.id.countdown);
    }

    @Override
    protected void onStart() {
        super.onStart();
        timer = new Timer("DigitalClock");
        Calendar calendar = Calendar.getInstance();

        // Get the Current Time
        final Runnable updateTask = new Runnable() {
            public void run() {
                countdown.setText(getCurrentTimeString()); // shows the current time of the day
//                countdown.setText(getReminingTime()); // shows the remaining time of the day
            }
        };

        // update the UI
        int msec = 999 - calendar.get(Calendar.MILLISECOND);
        timer.scheduleAtFixedRate(new TimerTask() {
            @Override
            public void run() {
                runOnUiThread(updateTask);
            }
        }, msec, 1000);
    }

    @Override
    protected void onStop() {
        super.onStop();
        timer.cancel();
        timer.purge();
        timer = null;
    }
   private String getReminingTime() {
        Calendar calendar = Calendar.getInstance();
        int hour = 23 - calendar.get(Calendar.HOUR_OF_DAY);
        int minute = 59 - calendar.get(Calendar.MINUTE);
        int second = 59 - calendar.get(Calendar.SECOND);
        return String.format("%02d:%02d:%02d", hour, minute, second);
    }



    private String getCurrentTimeString() {
        Calendar calendar = Calendar.getInstance();
        int hour = calendar.get(Calendar.HOUR_OF_DAY);
        int minute = calendar.get(Calendar.MINUTE);
        int second = calendar.get(Calendar.SECOND);
        return String.format("%02d:%02d:%02d %02d", hour, minute, second);
    }
}

Creating dynamic Customized List view.

This article shows to create a dynamic custom view as a list. i have created a custom adapter and explore to create a custom listview.
As a result i have created the below method. In this blog will help you to create a customized list view.

Create two layout
    1. main layout
    2. custom view layout.

MainLayout - which is used to define the scroll view.
    <?xml version="1.0" encoding="utf-8"?>
    <ScrollView android:id="@+id/ScrollView01"
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_height="fill_parent" android:layout_width="fill_parent">
        <LinearLayout android:orientation="vertical"
            android:layout_width="fill_parent" android:id="@+id/mylayout1"
            android:layout_height="wrap_content">
        </LinearLayout>
    </ScrollView>


Custom Layout - Which Consists of actual design.
    <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout android:orientation="vertical"
        android:layout_width="fill_parent" android:layout_height="wrap_content"
        xmlns:android="http://schemas.android.com/apk/res/android">
        <TextView android:text="@+id/TextView01" android:id="@+id/TextView01"
            android:layout_width="wrap_content" android:layout_height="wrap_content"></TextView>
        <Button android:text="@+id/Button01" android:id="@+id/Button01"
            android:layout_width="wrap_content" android:layout_height="wrap_content"></Button>
    </LinearLayout>




Create a Activity Class

public class DynamicListActivity extends Activity {
    /**
     * @see android.app.Activity#onCreate(Bundle)
     */
    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.listviewmain);
    LinearLayout l = (LinearLayout) findViewById(R.id.mylayout1);
    LayoutInflater linflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    for (int i = 0; i < 5; i++) {
        View customView = linflater.inflate(R.layout.customlistviewitem,
            null);
        TextView tv = (TextView) customView.findViewById(R.id.TextView01);
        Button btn = (Button) customView.findViewById(R.id.Button01);
        tv.setId(i);
        btn.setId(i);
        tv.setText("Location:" + i);
        btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Toast.makeText(DynamicListActivity.this, v.getId() + "",
                Toast.LENGTH_LONG).show();
        }
        });
        l.addView(customView);
    }
    }
}

UtilMethod For Android - I

I have collected some Utility method from my code.

/** Return a specific file contents as a String value. */
public static String getFileString(File file) throws Exception {
    String result = null;
    InputStream is = null;
    ByteArrayOutputStream os = new ByteArrayOutputStream();
    try {
        is = new FileInputStream(file);
        int bytesRead;
        byte[] buffer = new byte[1024];
        while ((bytesRead = is.read(buffer)) != -1) {
            os.write(buffer, 0, bytesRead);
        }
        os.flush();
        result = new String(os.toByteArray());
    } catch(Exception e) {
        throw new Exception("Problem while reading file", e);
    } finally {
        try {
            os.close();
            is.close();
        } catch(Exception e) {
        }
    }
    return result;
}

/** Return a specific url contents as a String value. */
public static String getUrlString(String remoteUrl) throws Exception {
    String result = null;
    InputStream is = null;
    ByteArrayOutputStream os = new ByteArrayOutputStream();
    try {
        URL url = new URL(remoteUrl);
        URLConnection connection = url.openConnection();
        connection.setConnectTimeout(5000);
        connection.setReadTimeout(5000);
        connection.connect();
        is = connection.getInputStream();
        int bytesRead;
        byte[] buffer = new byte[1024];
        while ((bytesRead = is.read(buffer)) != -1) {
            os.write(buffer, 0, bytesRead);
        }

        os.flush();
        result = new String(os.toByteArray());
    } catch(Exception e) {
        throw new Exception("Problem while reading targeted url", e);
    } finally {
        try {
            os.close();
            is.close();
        } catch(Exception e) {
        }
    }
    return result;
}

/** Create Thumbnail Image
* Param1 : Image,
* Param2 : Required Size */

public static Drawable createIconThumbnail(Drawable icon, int size) {
    int sourceWidth = icon.getIntrinsicWidth(),
    sourceHeight = icon.getIntrinsicHeight();
   
    int destWidth = size, destHeight = size;
   
    // only resize if actually needed
    if(sourceWidth != destWidth || sourceHeight != destHeight) {
        float ratio = (float) sourceWidth / sourceHeight;
        if(sourceWidth > sourceHeight) {
            destHeight = (int) (destWidth / ratio);
        } else if (sourceHeight > sourceWidth) {
            destWidth = (int) (destHeight * ratio);
        }

        final Bitmap thumb = Bitmap.createBitmap(size, size, Bitmap.Config.ARGB_8888);
        final Canvas canvas = new Canvas(thumb);

        icon.setBounds((size - destWidth) / 2, (size - destHeight) / 2, destWidth, destHeight);
        icon.draw(canvas);
        icon = new BitmapDrawable(thumb);
    }
    return icon;
}

/** Return a current time a String value. */
 private String getCurrentTimeString() {
        Calendar calendar = Calendar.getInstance();
        int hour = calendar.get(Calendar.HOUR_OF_DAY);
        int minute = calendar.get(Calendar.MINUTE);
        int second = calendar.get(Calendar.SECOND);
        return String.format("%02d:%02d:%02d ", hour, minute, second);
    }

Create a Apps to Show Digital Time in Android

this blog helps to create a simple digital clock in andriod.

Create a Layout.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="fill_parent"
    android:layout_height="fill_parent">

    <TextView android:id="@+id/countdown" android:layout_width="320dip"
        android:layout_height="120dip" android:text="00:00:00"
        android:textSize="15pt" android:textColor="#00C2FF"
        android:layout_centerInParent="true" />
</RelativeLayout>


Create Activty Class for show the Time

public class MainActivity extends Activity {
    private TextView countdown;
    private Timer timer;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        TextView countdown = (TextView) findViewById(R.id.countdown);
    }

    @Override
    protected void onStart() {
        super.onStart();
        timer = new Timer("DigitalClock");
        Calendar calendar = Calendar.getInstance();

        // Get the Current Time
        final Runnable updateTask = new Runnable() {
            public void run() {
                countdown.setText(getCurrentTimeString());
            }
        };

        // update the UI
        int msec = 999 - calendar.get(Calendar.MILLISECOND);
        timer.scheduleAtFixedRate(new TimerTask() {
            @Override
            public void run() {
                runOnUiThread(updateTask);
            }
        }, msec, 1000);
    }

    @Override
    protected void onStop() {
        super.onStop();
        timer.cancel();
        timer.purge();
        timer = null;
    }

    private String getCurrentTimeString() {
        Calendar calendar = Calendar.getInstance();
        int hour = calendar.get(Calendar.HOUR_OF_DAY);
        int minute = calendar.get(Calendar.MINUTE);
        int second = calendar.get(Calendar.SECOND);
        return String.format("%02d:%02d:%02d %02d", hour, minute, second);
    }
}

UI component Snippets

In this article having the set of android sinppets used to set the value and listener action.

Spinner Control

      String selectedState  ="";
    String[] stateList = new String[] { "Select State", "MA", "NY" }; // Dropdown values
    Spinner sprState = (Spinner) findViewById(R.id.sprstate);

    // Set the value using the ArrayAdapter
    ArrayAdapter<String> stateListAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_spinner_item,stateList);
    stateListAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    stateListAdapter.setAdapter(stateList);

    // Listener
    sprState.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parent,View view, int position, long id) {
        selectedState = String.valueOf(sprState.getSelectedItem());
        }

        @Override
        public void onNothingSelected(AdapterView<?> parent) {
        }
    });


ListView Control

    ArrayList<String> tempListViewData = new ArrayList<String>();
   tempListViewData.add("One");
   tempListViewData.add("two");

   ListView l = (ListView) findViewById(R.id.ListView01);

    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_dropdown_item_1line, tempListViewData);
    l.setAdapter(adapter);

    l.setOnItemClickListener(new OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
            long arg3) {
        Log.d("Position", arg2 + "");       
        }
    });

Button
Button btnFindStore = (Button) findViewById(R.id.btnhomego);
    private class FindStoreListener implements
            android.view.View.OnClickListener {
        @Override
        public void onClick(View v) {
       }
    }

btnCityStateOption.setOnClickListener(new FindStoreListener());

EditText
    EditText etUserInput = (EditText) findViewById(R.id.etuserinput);
    String.valueOf(etUserInput.getText()).trim();
   

Find Current Location in Android - GPS Sample

This article will show you how to programmatically access the data returned by your built-in GPS receiver.

In Android, location-based services are provided by the LocationManager class located in the android.location package.

Using the LocationManager class, we can obtain periodic updates of the device's geographical locations as well as fire an intent when it enters the proximity of a certain location.


1. Obtain a reference to the LocationManager class using the getSystemService() method.
    LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);


2. Create a LocationListener Class for notify the location changes.
Our MyLocationListener class should implements the LocationListener abstract class. There are four methods that you need to override in this implementation:
    * onLocationChanged(Location location): This method is called when the location has changed.
    * onProviderDisabled(String provider): This method is called when the provider is disabled by the user.
    * onProviderEnabled(String provider): This method is called when the provider is enabled by the user.
    * onStatusChanged(String provider, int status, Bundle extras): This method is called when the provider status changes.


3. To be notified whenever there is a change in location, you need to register for a request for changes in locations so that your program can be notified periodically. This is done via the requestLocationUpdates() method (see Listing 1).

This method takes in four parameters:
    * provider: The name of the provider with which you register
    * minTime: The minimum time interval for notifications, in milliseconds.
    * minDistance: The minimum distance interval for notifications, in meters.
    * listener: An object whose onLocationChanged() method will be called for each location update.

4. Set the following User-Permission  in androidmanifest.xml
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"></uses-permission>


Sample Code :
MainActivity.java
public class MainActivity extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    LocationListener ll = new mylocationlistener();
    lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, ll);
    }

    private class mylocationlistener implements LocationListener {
    @Override
    public void onLocationChanged(Location location) {
        if (location != null) {
        Log.d("LOCATION CHANGED", location.getLatitude() + "");
        Log.d("LOCATION CHANGED", location.getLongitude() + "");
        Toast.makeText(MainActivity.this,
            location.getLatitude() + "" + location.getLongitude(),
            Toast.LENGTH_LONG).show();
        }
    }
    @Override
    public void onProviderDisabled(String provider) {
    }
    @Override
    public void onProviderEnabled(String provider) {
    }
    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
    }
    }
}

Steps to implement ExpandableListView in android

3 Steps to implement the Expandable ListView  in android

Step 1 : Initilize the ExpandableListView and ExpandableListAdapter in a onCreate()

    ExpandableListAdapter mAdapter;
    ExpandableListView epView = (ExpandableListView) findViewById(R.id.ExpandableListView01);
    mAdapter = new MyExpandableListAdapter();
    epView.setAdapter(mAdapter);

Step 2 : Create a custom BaseApdapter Class
 /**
     * A simple adapter which maintains an ArrayList of photo resource Ids. Each
     * photo is displayed as an image. This adapter supports clearing the list
     * of photos and adding a new photo.
     *
     */
    public class MyExpandableListAdapter extends BaseExpandableListAdapter {
    // Sample data set. children[i] contains the children (String[]) for
    // groups[i].
    private String[] groups = { "Parent1", "Parent2",
        "Parent3" };
    private String[][] children = { { "Child1" },{ "Child2" }, { "Child3" },{ "Child4" }, { "Child5" } };

    public Object getChild(int groupPosition, int childPosition) {
        return children[groupPosition][childPosition];
    }

    public long getChildId(int groupPosition, int childPosition) {
        return childPosition;
    }

    public int getChildrenCount(int groupPosition) {
        int i = 0;
        try {
        i = children[groupPosition].length;

        } catch (Exception e) {
        }

        return i;
    }

    public TextView getGenericView() {
        // Layout parameters for the ExpandableListView
        AbsListView.LayoutParams lp = new AbsListView.LayoutParams(
            ViewGroup.LayoutParams.FILL_PARENT, 64);

        TextView textView = new TextView(MainActivity.this);
        textView.setLayoutParams(lp);
        // Center the text vertically
        textView.setGravity(Gravity.CENTER_VERTICAL | Gravity.LEFT);
        textView.setTextColor(R.color.marcyred);
        // Set the text starting position
        textView.setPadding(36, 0, 0, 0);
        return textView;
    }

    public View getChildView(int groupPosition, int childPosition,
        boolean isLastChild, View convertView, ViewGroup parent) {
        TextView textView = getGenericView();
        textView.setText(getChild(groupPosition, childPosition).toString());
        return textView;
    }

    public Object getGroup(int groupPosition) {
        return groups[groupPosition];
    }

    public int getGroupCount() {
        return groups.length;
    }

    public long getGroupId(int groupPosition) {
        return groupPosition;
    }

    public View getGroupView(int groupPosition, boolean isExpanded,
        View convertView, ViewGroup parent) {
        TextView textView = getGenericView();
        textView.setText(getGroup(groupPosition).toString());
        return textView;
    }

    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return true;
    }

    public boolean hasStableIds() {
        return true;
    }

    }
   
3. Listeners
    epView.setOnGroupClickListener(new OnGroupClickListener() {
        @Override
        public boolean onGroupClick(ExpandableListView arg0, View arg1,
            int groupPosition, long arg3) {
        if (groupPosition == 5) {               

        }
        return false;
        }
        });

    epView.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {
    @Override
    public boolean onChildClick(ExpandableListView parent,
            View v, int groupPosition, int childPosition,
            long id) {
        if (groupPosition == 0 && childPosition == 0) {
           
        }
        return false;
    }
    });

Utility Calss - ImageMangerHelper

The Following Code snippets used to fetching the image from targeted image URL

/**
 * ImageManager is used to fetch the image from the targeted url. It is a
 * immutable pattern.
 *
 * @author ganesan_sh
 *
 */
public final class ImageManager {

    static ImageManager imageManager = null;
    private static long updatedTime = 0;
    private static long resetPeriod = 4320000;
    private static Bitmap bmImg;

    private ImageManager() {
    }

    public static ImageManager getImageManagerInstance(String imageURL) {
    long currTime = System.currentTimeMillis();
    if (((currTime - updatedTime) > resetPeriod) || imageManager == null) {
        imageManager = new ImageManager();
        fetchAdvBannerImage(imageURL);
    }
    return imageManager;
    }

    static void fetchAdvBannerImage(String fileUrl) {
    URL myFileUrl = null;
    try {
        myFileUrl = new URL(fileUrl);
    } catch (MalformedURLException e) {
    }
    try {
        HttpURLConnection conn = (HttpURLConnection) myFileUrl
            .openConnection();
        conn.setDoInput(true);
        conn.connect();
        int length = conn.getContentLength();
        InputStream is = conn.getInputStream();
        bmImg = BitmapFactory.decodeStream(is);

    } catch (IOException e) {
    }
    }

    public Bitmap getBannerImage() {
    return bmImg;
    }
}

Retrieve Application Names

Here the following code snippet used to retrieve the installed package in your device

  ListView programsList;
   PackageManager mPackageManager;
 

   programsList = (ListView) findViewById(R.id.ListView01);
    programsList.setTextFilterEnabled(true);
    mPackageManager = getPackageManager();
    List<String> packageName = new ArrayList<String>(); 
    List<ResolveInfo> list = mPackageManager.queryIntentActivities(
        new Intent(Intent.ACTION_MAIN), 0);
    for (ResolveInfo r : list) {
        packageName.add(r.loadLabel(mPackageManager).toString());
    }

    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_dropdown_item_1line,  
    packageName);
    programsList.setAdapter(adapter);

Content Provider Example - 3

Sample Code - MainActivity.java
public class MainActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
       
        Button btn1 = (Button) findViewById(R.id.Button01);
        Button btn2 = (Button) findViewById(R.id.Button02);
       
        btn1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                ContentValues values = new ContentValues();
                values.put(UserInfo.isactive, "Y");
                Uri uri = getContentResolver().insert(MyContentProvider.CONTENT_URI, values);
                Toast.makeText(MainActivity.this, "Item Added",Toast.LENGTH_LONG).show();
            }
        });

        btn2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String resultStr = "";
                Uri allTitles = Uri.parse("content://"+ MyContentProvider.PROVIDER_NAME + "/"+ UserInfo.DATABASE_TABLE);
                Cursor c = managedQuery(allTitles, null, null, null, "");
                if (c.moveToFirst()) {
                    do {
                        resultStr = c.getString(c.getColumnIndex(UserInfo._ID))+ ", "+ c.getString(c.getColumnIndex(UserInfo.isactive));
                        Toast.makeText(MainActivity.this, resultStr,Toast.LENGTH_LONG).show();
                    } while (c.moveToNext());
                }
            }
        });
    }

    public void readContact() {

        ArrayList<String> contactList;
        contactList = new ArrayList<String>();

        String[] columns = new String[] { People.NAME, People.NUMBER };
        Uri mContacts = People.CONTENT_URI;
        Cursor mCur = managedQuery(mContacts, columns, null, null, People.NAME+ " ASC ");
        if (mCur.moveToFirst()) {
            do {
                contactList.add(mCur.getString(mCur.getColumnIndex(People.NAME)));
            } while (mCur.moveToNext());
        }
        Toast.makeText(this, contactList.size() + "", Toast.LENGTH_LONG).show();
    }
}

-------------
MyContentProvider.java
public class MyContentProvider extends ContentProvider {
    public static final String PROVIDER_NAME = "com.contentproviderexample.mycontentprovider";
    public static final Uri CONTENT_URI = Uri.parse("content://"+ PROVIDER_NAME + "/demodb");   
    private static final UriMatcher uriMatcher;
    private SQLiteDatabase demoDB;   

    public static final class UserInfo implements BaseColumns {
        public static final String DATABASE_TABLE = "userinfo";
        public static final int USERINFO = 1;
        public static final int USERINFO_ID = 2;
        public static final Uri CONTENT_URI = Uri.parse("content://"+ PROVIDER_NAME + "/userinfo");
        public static final String CONTENT_TYPE = "vnd.android.cursor.dir/vnd.contentproviderexample.userinfo";
        public static final String CONTENT_ITEM_TYPE = "vnd.android.cursor.item/vnd.contentproviderexample.userinfo";
        public static final String _ID = "_id";
        public static final String isactive = "isactive";
    }

    static {
        uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
        uriMatcher.addURI(PROVIDER_NAME, UserInfo.DATABASE_TABLE,UserInfo.USERINFO);       
        uriMatcher.addURI(PROVIDER_NAME, UserInfo.DATABASE_TABLE + "/#",UserInfo.USERINFO);
    }

    @Override
    public boolean onCreate() {
        Context context = getContext();
        SQLiteConnectionManager dbHelper = new SQLiteConnectionManager(context);
        demoDB = dbHelper.getWritableDatabase();
        return (demoDB == null) ? false : true;
    }

    @Override
    public String getType(Uri uri) {
        switch (uriMatcher.match(uri)) {
        case UserInfo.USERINFO:
            return UserInfo.CONTENT_TYPE;
        case UserInfo.USERINFO_ID:
            return UserInfo.CONTENT_ITEM_TYPE;
        default:
            throw new IllegalArgumentException("Unsupported URI: " + uri);
        }
    }
    @Override
    public Uri insert(Uri uri, ContentValues values) {

        long rowID = demoDB.insert(UserInfo.DATABASE_TABLE, "", values);
        if (rowID > 0) {
            Uri _uri = ContentUris.withAppendedId(CONTENT_URI, rowID);
            getContext().getContentResolver().notifyChange(_uri, null);
            return _uri;
        }
        throw new SQLException("Failed to insert row into " + uri);
    }
    @Override
    public Cursor query(Uri uri, String[] projection, String selection,String[] selectionArgs, String sortOrder) {
        SQLiteQueryBuilder sqlBuilder = new SQLiteQueryBuilder();
        sqlBuilder.setTables(UserInfo.DATABASE_TABLE);
        if (uriMatcher.match(uri) == UserInfo.USERINFO_ID)
            sqlBuilder.appendWhere(UserInfo._ID + " = "+ uri.getPathSegments().get(1));
        Cursor c = sqlBuilder.query(demoDB, projection, selection,selectionArgs, null, null, sortOrder);
        c.setNotificationUri(getContext().getContentResolver(), uri);
        return c;
    }
    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        int count = 0;
        switch (uriMatcher.match(uri)) {
        case UserInfo.USERINFO:
            count = demoDB.delete(UserInfo.DATABASE_TABLE, selection,selectionArgs);
            break;

        case UserInfo.USERINFO_ID:
            String id = uri.getPathSegments().get(1);
            count = demoDB.delete(UserInfo.DATABASE_TABLE, UserInfo._ID+ " = "+ id+ (!TextUtils.isEmpty(selection) ? " AND (" + selection
                            + ')' : ""), selectionArgs);
            break;
           
            default:
                throw new IllegalArgumentException("Unknown URI " + uri);

        }
        getContext().getContentResolver().notifyChange(uri, null);
        return count;
    }
    @Override
    public int update(Uri uri, ContentValues values, String selection,String[] selectionArgs) {
        int count = 0;
        switch (uriMatcher.match(uri)) {
        case UserInfo.USERINFO:
            count = demoDB.update(UserInfo.DATABASE_TABLE, values, selection,selectionArgs);
            break;
        case UserInfo.USERINFO_ID:
            count = demoDB.update(UserInfo.DATABASE_TABLE, values, UserInfo._ID+ " = "+ uri.getPathSegments().get(1)
                    + (!TextUtils.isEmpty(selection) ? " AND (" + selection+ ')' : ""), selectionArgs);
            break;
        default:
            throw new IllegalArgumentException("Unknown URI " + uri);
        }
        getContext().getContentResolver().notifyChange(uri, null);
        return count;
    }
}
--------
SQLiteConnectionManager .java
public class SQLiteConnectionManager extends SQLiteOpenHelper {

    private static final String DATABASENAME = "DEMODB";
    private static final int DATABASE_VERSION = 1;
    private static final String CREATE_USERINFO = "CREATE TABLE userinfo(_id INTEGER NOT NULL CONSTRAINT USER_PK PRIMARY KEY AUTOINCREMENT,isactive TEXT DEFAULT 'Y')";
    public SQLiteConnectionManager(Context context) {
        super(context, DATABASENAME, null, DATABASE_VERSION);
    }
    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREATE_USERINFO);
        Log.d("@G SQLConnectionFactory", " CREATE_LEADSOURCE Table ");
    }
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    }
}

Content Provider Example - 2

Implement the business login in the override methods.
   
    Using the onCreate Method we can initilze the Database
        @Override
        public boolean onCreate() {
            Context context = getContext();
            SQLiteConnectionManager dbHelper = new SQLiteConnectionManager(context);
            demoDB = dbHelper.getWritableDatabase();
            return (demoDB == null) ? false : true;
        }

    getType method is used to validate the input url
        @Override
        public String getType(Uri uri) {
            switch (uriMatcher.match(uri)) {
            case UserInfo.USERINFO:
                return UserInfo.CONTENT_TYPE;
            case UserInfo.USERINFO_ID:
                return UserInfo.CONTENT_ITEM_TYPE;
            default:
                throw new IllegalArgumentException("Unsupported URI: " + uri);
            }
        }


    CRUD Operation

    Create - insert()
        long rowID = demoDB.insert(UserInfo.DATABASE_TABLE, "", values);
        if (rowID > 0) {
            Uri _uri = ContentUris.withAppendedId(CONTENT_URI, rowID);
            getContext().getContentResolver().notifyChange(_uri, null);
            return _uri;
        }

    Retrive - query()

        SQLiteQueryBuilder sqlBuilder = new SQLiteQueryBuilder();
        sqlBuilder.setTables(UserInfo.DATABASE_TABLE);
        if (uriMatcher.match(uri) == UserInfo.USERINFO_ID)
            sqlBuilder.appendWhere(UserInfo._ID + " = "+ uri.getPathSegments().get(1));
        Cursor c = sqlBuilder.query(demoDB, projection, selection,selectionArgs, null, null, sortOrder);
        c.setNotificationUri(getContext().getContentResolver(), uri);



    Update - update()
        int count = 0;
        switch (uriMatcher.match(uri)) {
        case UserInfo.USERINFO:
            count = demoDB.update(UserInfo.DATABASE_TABLE, values, selection,selectionArgs);
            break;

        case UserInfo.USERINFO_ID:
            count = demoDB.update(UserInfo.DATABASE_TABLE, values, UserInfo._ID+ " = "+ uri.getPathSegments().get(1)
                    + (!TextUtils.isEmpty(selection) ? " AND (" + selection+ ')' : ""), selectionArgs);
            break;
        default:
            throw new IllegalArgumentException("Unknown URI " + uri);
        }
        getContext().getContentResolver().notifyChange(uri, null);



  Delete - delete()   
    int count = 0;
    switch (uriMatcher.match(uri)) {
        case UserInfo.USERINFO:
            count = demoDB.delete(UserInfo.DATABASE_TABLE, selection,selectionArgs);
            break;
        case UserInfo.USERINFO_ID:
            String id = uri.getPathSegments().get(1);
            count = demoDB.delete(UserInfo.DATABASE_TABLE, UserInfo._ID+ " = "+ id+ (!TextUtils.isEmpty(selection) ? " AND (" + selection+ ')' : ""), selectionArgs);
            break;
        default:
            throw new IllegalArgumentException("Unknown URI " + uri);
        }
        getContext().getContentResolver().notifyChange(uri, null);

Create a Database Helper to Create database Schema
Refer : http://about-android.blogspot.com/2009/12/android-hello-world-activity-sample.html

Accessing Our Content Provider
    Create or Insert
        ContentValues values = new ContentValues();
        values.put(UserInfo.isactive, "Y");
        Uri uri = getContentResolver().insert(MyContentProvider.CONTENT_URI, values);

    Retrieve
        String resultStr = "";
        Uri allTitles = Uri.parse("content://"+ MyContentProvider.PROVIDER_NAME + "/"+ UserInfo.DATABASE_TABLE);

        Cursor c = managedQuery(allTitles, null, null, null, "");
        if (c.moveToFirst()) {
            do {
                resultStr = c.getString(c.getColumnIndex(UserInfo._ID))+ ", "+ c.getString(c.getColumnIndex(UserInfo.isactive));
                Toast.makeText(MainActivity.this, resultStr,Toast.LENGTH_LONG).show();
            } while (c.moveToNext());
        }

Content Provider Example - 1

In Android, a content provider is a specialized type of data store that exposes standardized ways to retrieve and manipulate the stored data.

You wish to share data between applications, you need to use the content provider model as recommended in Android. This article presents the basics of content providers and how you can implement one.

We are going to discuss following item here
  1. Using a Content Provider
  2. Create a Custom Content Provider

Using a Content Provider
Here are some of Android's most useful built-in content providers
Content Provider     Intended Data
Contacts                Contact details
Browser                 Browser bookmarks, browser history, etc.
CallLog                   Missed calls, call details, etc.
MediaStore             Media files such as audio, video and images
Settings                 Device settings and preferences

Here are the sample method for accessing the Contacts Content Provider.

public void readContact() {   
        ArrayList<String> contactList;
        contactList = new ArrayList<String>();

        String[] columns = new String[] { People.NAME, People.NUMBER };
        Uri mContacts = People.CONTENT_URI;
        Cursor mCur = managedQuery(mContacts, columns, null, null, People.NAME+ " ASC ");
        if (mCur.moveToFirst()) {
            do {
                contactList.add(mCur.getString(mCur.getColumnIndex(People.NAME)));
            } while (mCur.moveToNext());
        }
        Toast.makeText(this, contactList.size() + "", Toast.LENGTH_LONG).show();
    }


Create a Custom Content Provider
1. Create a Content Provier Class
2. Override the Following Methods
3. Declare the Constant Content Provider Values.
4. Implement the business login in the override methods.
5. Create a Database Helper to Create database Schema
6. Accessing Our Content Provider

Create a Content Provier Class
    Create a customized class which extend the ContentProvider Class. ContentProvider is an abstract Class, so we need to override the method in the content provider class.
        public class MyContentProvider extends ContentProvider{}

Override the Following Methods

    * onCreate(): Called when the provider is being started.
    * getType(): Returns the MIME type of the data at the given URI.       

    CRUD Operation
    * insert(): Inserts a new record into the content provider.
    * query(): Receives a request from a client. The result is returned as a Cursor object.
    * update(): Updates an existing record from the content provider.
    * delete(): Deletes an existing record from the content provider.          

   
   
Declare the Constant Content Provider Values.

1. Provider Name - Which is used to access the content provider.
        1. Standard prefix indicating that the data is controlled by a content provider. IT'S NEVER MODIFIED.
        2.The authority part of the URI; it identifies the content provider. For third-party applications, this should be a fully-qualified class name (reduced to lowercase) to ensure uniqueness. The authority is declared in the <provider> element's authorities attribute:
            <provider name=".TransportationProvider" authorities="com.example.transportationprovider"  . .  >
        3. The path that the content provider uses to determine what kind of data is being requested. This can be zero or more segments long. If the content provider exposes only one type of data (only trains, for example), it can be absent. If the provider exposes several types, including subtypes, it can be several segments long for example, "land/bus", "land/train", "sea/ship", and "sea/submarine" to give four possibilities.
        4. The ID of the specific record being requested, if any. This is the _ID value of the requested record. If the request is not limited to a single record, this segment and the trailing slash are omitted:

Example
         public static final String PROVIDER_NAME = "com.contentproviderexample.mycontentprovider"; // Same as Androidmanifest.xml entry
         public static final Uri CONTENT_URI = Uri.parse("content://"+ PROVIDER_NAME + "/demodb"); // URI for access the Content Provider


 2. Create a VO for Table with some content Provider Value
        For example i have create a table userinfo which contains the two column [id and isalive]. i have created the following VO class

 public static final class UserInfo implements BaseColumns {
            public static final String DATABASE_TABLE = "userinfo";
            public static final int USERINFO = 1;
            public static final int USERINFO_ID = 2;

            public static final Uri CONTENT_URI = Uri.parse("content://"
                    + PROVIDER_NAME + "/userinfo");
            public static final String CONTENT_TYPE = "vnd.android.cursor.dir/vnd.contentproviderexample.userinfo";
            public static final String CONTENT_ITEM_TYPE = "vnd.android.cursor.item/vnd.contentproviderexample.userinfo";

            public static final String _ID = "_id";
            public static final String isactive = "isactive";
        }

 3.Create  a object for UriMatcher. and add the our URL with UriMatcher
        static {
        uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
        uriMatcher.addURI(PROVIDER_NAME, UserInfo.DATABASE_TABLE,UserInfo.USERINFO);
        uriMatcher.addURI(PROVIDER_NAME, UserInfo.DATABASE_TABLE + "/#",UserInfo.USERINFO);
        }