android add activity parent manifest
<!-- The main/home activity (it has no parent activity) -->
<activity
android:name="com.example.app_name.A" ...>
...
</activity>
<!-- A child of the main activity -->
<activity
android:name=".B"
android:label="B"
android:parentActivityName="com.example.app_name.A" >
<!-- Parent activity meta-data to support 4.0 and lower -->
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.example.app_name.A" />
</activity>