Question

1.open from notification bar
2.press home return to desttop
3.open from app icon

problem:2 instance of SampleTabsDefault, need to exit twice.

    Intent intent = new Intent(_context, SampleTabsDefault.class);
    intent.setFlags(/*Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP |*/ Intent.FLAG_ACTIVITY_NEW_TASK);
    PendingIntent activity = PendingIntent.getActivity(_context, 0, intent, 0);
    notification.contentIntent = activity;

Answer 1

Try below code in AndroidMenifest.xml file within your activity nod.

<activity name="SampleTabsDefault"
android:clearTaskOnLaunch="true"
android:finishOnTaskLaunch="true"
>
.....
</activity>

Please read both attributes description here.

Hope this will solve your problem