Question

So here is my activity.

<activity
            android:name=".MainActivity_Hard"
            android:configChanges="keyboardHidden|orientation|screenSize"
            android:label="@string/title_activity_main_activity__hard"
            android:noHistory="true"
            android:screenOrientation="portrait" >
        </activity>

I marked it as android:noHistory=”true” because I did not want the screen to be added to the activity stack.

But however when I lock the screen and unlock it. The activity disappears and the previous screen appears. This should not happen. Could anyone tell me why.

Note: It happens in ICS (Samsung Galaxy Note), but not with previous devices (Gingerbread,etc.)

Answer 1

Setting the noHistory attribute in your activity means that as soon as the user navigates away from that activity–bringing up the lock screen included–its finish() function is called automatically, thus destroying it and going back to the previous activity that spawned it.

This is typically used for splash-screen-type activities which, for example, acts only as a launcher and you don’t want the user to be able to go back to the splash screen from the child.

If this is not your intention, then you should consider removing the noHistory attribute and maybe managing the activity lifecycle yourself. (For example, if you don’t want your activity to be in the stack, then just call finish() just after it starts another activity.)

android:noHistory

Whether or not the activity should be removed from
the activity stack and finished (its finish() method called) when the
user navigates away from it and it’s no longer visible on screen —
"true" if it should be finished, and "false" if not. The default value
is "false". A value of "true" means that the activity will not leave a
historical trace. It will not remain in the activity stack for the
task, so the user will not be able to return to it.