Up Navigation not launching parent activity

Question

I have two activities A and B where A is the parent of B. Now I show a notification that launches B. when I tap on the notification, B launches. Then I click on the up button. It works finr when activity A is in the backstack but otherwise the app Just closes and does not launch activity A.

My Setup.

I have declared A as Parent of B in Manifest with A in SingleTop launchMode

<activity
        android:name=".A"
        android:label="@string/app_name"
        android:screenOrientation="portrait"
        android:launchMode="singleTop"
        android:theme="@style/AppTheme.NoActionBar">
        <intent-filter>
            <action android:name="<packegeName>.Home" />
        </intent-filter>
    </activity>
    <activity
        android:name=".B"
        android:label="@string/app_name"
        android:screenOrientation="portrait"
        android:parentActivityName=".A"
        android:theme="@style/AppTheme.NoActionBar">
        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value=".A" />
    </activity>

This is the notification Intent :

Intent intent = new Intent(this, B.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent, 
                                                        PendingIntent.FLAG_ONE_SHOT);

In Activity B :

@Override
public void onCreate(Bundle savedInstanceState) {
    ....
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    ....
}

What I've tried

In order to debug I've tried manually triggering this up navigation in Activity B's onResume, with all of these :

1)

Intent upIntent = NavUtils.getParentActivityIntent(this);
upIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
if (NavUtils.shouldUpRecreateTask(this, upIntent)) {
    // This activity is NOT part of this app's task, so create a new task
    // when navigating up, with a synthesized back stack.
    TaskStackBuilder.create(this)
            // Add all of this activity's parents to the back stack
            .addNextIntentWithParentStack(upIntent)
            // Navigate up to the closest parent
            .startActivities();
} else {
    // This activity is part of this app's task, so simply
    // navigate up to the logical parent activity.
    NavUtils.navigateUpTo(this, upIntent);
}

2)

onNavigateUp();

3)

NavUtils.navigateUpFromSameTask(this);

But none of these seem to work when Activity A is not in the Backstack, the app just exits.

I have scoured SO and Google (even bing!) looking for an answer and tried everything I could find to no avail. As there is no error or log output, I also have no idea how to debug this.

Any solution or tips on finding out the issue will be greatly appreciated.

Thanks.

Answer 1

Try the approach described for Synthesize a new Back Stack for Deep Links

You will have use TaskStackBuild to build the back stack and get the PendingIntent when starting on Activity B.

Check this video from Android Design Patterns explains it simple.