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

Use this code very simple solution

 @Override
    public void onBackPressed() {
      super.onBackPressed(); // this line close the  app on backpress
 }

Answer 2

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 3

This one work for me.I found it myself by combining other answers

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() {
             // TODO Auto-generated method stub
             Intent a = new Intent(Intent.ACTION_MAIN);
             a.addCategory(Intent.CATEGORY_HOME);
             a.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
             startActivity(a);
        }
    }, 1000);
}

Answer 4

In my understanding Google wants Android to handle memory management and shutting down the apps. If you must exit the app from code, it might be beneficial to ask Android to run garbage collector.

@Override
public void onBackPressed(){
    System.gc();
    System.exit(0);
}

You can also add finish() to the code, but it is probably redundant, if you also do System.exit(0)

Answer 5

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);