Thanks Rolf...
I've already tried that way before, when we press back button while soft keyboard active it will close the keyboard first than we must press back button again to show the exit dialog.
What i want is to show exit dialog when back button pressed only once without closing soft keyboard or to press back button twice.
Actually i'm currently developing typing game, so i think it's better to prevent the soft keyboard to be close by accidentally if the user press back button.
i'm talking about something like in this game: https://market.android.com/details?id=biz.mobidev.burningfingers