Android: Quit application when press back button

Question

In my application i want exit from app when press back button, this my code:

@Override     public void onBackPressed() {         new AlertDialog.Builder(this).setIcon(android.R.drawable.ic_dialog_alert).setTitle("Exit")                 .setMessage("Are you sure you want to exit?")                 .setPositiveButton("Yes", new DialogInterface.OnClickListener() {                     @Override                     public void onClick(DialogInterface dialog, int which) {                         finish();                     }                 }).setNegativeButton("No", null).show();     } 

it's work correctly but when i exit from app it does not exit completely and show empty page with my app logo and when i again press back button exit from app, How can i fix it???

EDIT :

I use this code instead of above but my app exit completely but i want it running at background and does not exit completely , how can i do it?

@Override     public void onBackPressed() {         new AlertDialog.Builder(this).setIcon(android.R.drawable.ic_dialog_alert).setTitle("Exit")                 .setMessage("Are you sure?")                 .setPositiveButton("yes", new DialogInterface.OnClickListener() {                     @Override                     public void onClick(DialogInterface dialog, int which) {                          Intent intent = new Intent(Intent.ACTION_MAIN);                         intent.addCategory(Intent.CATEGORY_HOME);                         intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);                         startActivity(intent);                         finish();                     }                 }).setNegativeButton("no", null).show();     }  

Answer 1

When you press back and then you finish your current activity(say A), you see a blank activity with your app logo(say B), this simply means that activity B which is shown after finishing A is still in backstack, and also activity A was started from activity B, so in activity, You should start activity A with flags as

Intent launchNextActivity; launchNextActivity = new Intent(B.class, A.class); launchNextActivity.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); launchNextActivity.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);                   launchNextActivity.addFlags(Intent.FLAG_ACTIVITY_NO_ANIMATION); startActivity(launchNextActivity); 

Now your activity A is top on stack with no other activities of your application on the backstack.

Now in the activity A where you want to implement onBackPressed to close the app, you may do something like this,

private Boolean exit = false; @Override     public void onBackPressed() {         if (exit) {             finish(); // finish activity         } else {             Toast.makeText(this, "Press Back again to Exit.",                     Toast.LENGTH_SHORT).show();             exit = true;             new Handler().postDelayed(new Runnable() {                 @Override                 public void run() {                     exit = false;                 }             }, 3 * 1000);          }      } 

The Handler here handles accidental back presses, it simply shows a Toast, and if there is another back press within 3 seconds, it closes the application.

Answer 2

Try this:

Intent intent = new Intent(Intent.ACTION_MAIN);           intent.addCategory(Intent.CATEGORY_HOME);           intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);//***Change Here***           startActivity(intent);           finish();           System.exit(0);