Exit android app on back pressed

Question

I am building an Android App. How to exit an Android App when back is pressed. Android version is 2.3.3 and above. The Android App goes to previous activity which i don\'t want.

Answer 1

Pop Up

     @Override
     public void onBackPressed() {
     new AlertDialog.Builder(this)
       .setTitle("Really Exit?")
       .setMessage("Are you sure you want to exit?")
       .setNegativeButton(android.R.string.no, null)
       .setPositiveButton(android.R.string.yes, new OnClickListener() {

    public void onClick(DialogInterface arg0, int arg1) {
    WelcomeActivity.super.onBackPressed();
        }
    }).create().show();

}

Set Class to Top of App and no history

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);

enter code here Double back press

private static long back_pressed;
@Override
public void onBackPressed(){
if (back_pressed + 2000 > System.currentTimeMillis()){
super.onBackPressed();
}
else{
Toast.makeText(getBaseContext(), "Press once again to exit", 
Toast.LENGTH_SHORT).show();
back_pressed = System.currentTimeMillis();
}

}