Updated Answer: Up Navigation Design
You have to declare which activity is the appropriate parent for each activity. Doing so allows the system to facilitate navigation patterns such as Up because the system can determine the logical parent activity from the manifest file.
So for that you have to declare your parent Activity in tag Activity with attribute
android:parentActivityName
Like,
<!-- 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>
With the parent activity declared this way, you can navigate Up to the appropriate parent like below,
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
// Respond to the action bar's Up/Home button
case android.R.id.home:
NavUtils.navigateUpFromSameTask(this);
return true;
}
return super.onOptionsItemSelected(item);
}
So When you call NavUtils.navigateUpFromSameTask(this); this method, it finishes the current activity and starts (or resumes) the appropriate parent activity. If the target parent activity is in the task's back stack, it is brought forward as defined by FLAG_ACTIVITY_CLEAR_TOP.
And to display Up button you have to declare setDisplayHomeAsUpEnabled():
@Override
public void onCreate(Bundle savedInstanceState) {
...
getActionBar().setDisplayHomeAsUpEnabled(true);
}
Old Answer: (Without Up Navigation, default Back Navigation)
It happen only if you are starting Activity A again from Activity B.
Using startActivity().
Instead of this from Activity A start Activity B using startActivityForResult() and override onActivtyResult() in Activity A.
Now in Activity B just call finish() on button Up. So now you directed to Activity A's onActivityResult() without creating of Activity A again..