Run class constantly on screen.

If we have a always running on screen app, we need to check if activity has been send to background, for example user press Home button, we bring it back to foreground.

Create a service.

public class newse extends Service {

 private static final int INTERVAL = 3000; // poll every 3 secs

 private static final String YOUR_APP_PACKAGE_NAME = "com.example.vidu";

   private static boolean stopTask;

    private PowerManager.WakeLock mWakeLock;

    @Override

    public void onCreate() {

        super.onCreate();

        stopTask = false;

       

     final ActivityManager activityManager = (ActivityManager) this

                        .getSystemService(Context.ACTIVITY_SERVICE);

        // Start your (polling) task

        TimerTask task = new TimerTask() {

            @Override

            public void run() {

                // If you wish to stop the task/polling

                if (stopTask){

                    this.cancel();

                }

List<ActivityManager.RunningAppProcessInfo> tasks = activityManager.getRunningAppProcesses();

String foregroundTaskPackageName = tasks.get(0).processName;

// Check foreground app: If it is not in the foreground... bring it!

if (!foregroundTaskPackageName.equals(YOUR_APP_PACKAGE_NAME)) {

Intent LaunchIntent = getPackageManager()

          .getLaunchIntentForPackage(YOUR_APP_PACKAGE_NAME);

                     startActivity(LaunchIntent);

               }

            }

        };

    Timer timer = new Timer();

        timer.scheduleAtFixedRate(task, 0, INTERVAL);

   }

    @Override

    public void onDestroy(){

        stopTask = true;

        if (mWakeLock != null)

            mWakeLock.release();

        super.onDestroy();

    }

     @Override

     public IBinder onBind(Intent intent) {

          // TODO Auto-generated method stub

          return null;

     }

}

String YOUR_APP_PACKAGE_NAME must be your package name.

Declare service in to file AndroidManifest.xml, above last </application>.

<service

android:name=".newse"

android:enabled="true"

android:exported="false"/>

In class need to bring back, add these lines to above last close bracket.

@Override

     public void onWindowFocusChanged(boolean hasFocus) {

          super.onWindowFocusChanged(hasFocus);

          if (!hasFocus) {

     Intent intent = new Intent(this, newse.class);

     intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

     startService(intent);         

     }

     }

After call service, we need to close when done, if not, it will make phone battery exhaust.

Intent intent = new Intent(this, newse.class);

intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

stopService(intent);

You can use only the line stopService(intent), but sometime you must create function to ensure it closed.

We need to listen 3 button Back, Home, Menu, call service when detect button pressed.