how to finish multiple instances of an activity at once in android

The activities in stack are A,B1,B2,B3,B4. if i press back button in B4(activity) i should finish all the instances of B activity and it shoul开发者_如何转开发d take me to the A activity.

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On B4 you should call the below method:

@Override
public void onBackPressed() {
 startActivity(new Intent(this, A.class)
 .setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP));
 return;
}