Question

some applications (like for example the Dolphin HD Browser) implement the following feature:

Pressing “Back” jumps back in the back stack. When the initial view/activity/fragment is shown and you press “Back”, a Toast appears saying “Press Back again to quit” or something similar.

How could I implement this feature?

Answer 1

Catch the back-button event like so:

public void onBackPressed() 
{
    //Add your logic here
    return;
}

Now create a flag so your application won’t close the first time it fires.
Finally end your activity by calling finish(); on your activity.

For quickly showing Toasts use this:

Toast.makeText(this, "Press Back again to quit", Toast.LENGHT_SHORT).show();

Provided that you’re launching this code from your activity class. If not, try to get the context of your activity instead of using this.