MainActivity.java

// Write this in onBackPress of your MainActivity
public class MainActivity extends AppCompatActivity{
  
    @Override
    public void onBackPressed() {
       super.onBackPressed();
       // This is important : Hack to open a dummy activity for 200-500ms (cannot be noticed by user as it is for 500ms
       //  and transparent floating activity and auto finishes)
       startActivity(new Intent(this, DummyActivity.class));
       finish();
    }
  
}