Twice Back Button Exit [Android]

gistfile1.java

//Define as Actviity properties
private long backPressTime;
private static final int DOUBLE_BACK_TIME_LIMIT = 800;

//Define method that will perform the "magic"
private void doubleBackPressTrigger() {
  if (backPressTime + DOUBLE_BACK_TIME_LIMIT > System.currentTimeMillis()) {
    super.onBackPressed();
  }else {
    Toast.makeText(getBaseContext(), "Press \"Back\" twice to get out of the application!", Toast.LENGTH_SHORT).show();
  }
  backPressTime = System.currentTimeMillis();
}

//Put in your activity you want to be enabled with "double back exit"
@Override
public void onBackPressed() {
  doubleBackPressTrigger();
}