Why and How to use TaskStackBuilder in Android?

Q: Why?

A: To provide proper navigation.

1. When the app is launched by App icon (Normal Flow)

2) When the app is launched by some Notification

The general flow of navigation in your app is MainActivity->DetailActivity

But sometimes a Notification might directly open the DetailActivity. In this case, pressing the back button will not lead you to the `MainActivity. It's an EXPECTED BEHAVIOR. However, you can modify this if you want to navigate back to MainActivity.

How?

1. Declare Parent of DetailActivity.

android:parentActivityName=".Activities.MainActivity" add this in Manifest file.

So it will look like this.

<activity android:name=".Activities.DetailActivity"
    android:parentActivityName=".Activities.MainActivity">
</activity>

But! this feature was added in Android 4.1. So if you want to target older devices. Add a meta-tag as well.

<activity android:name=".Activities.DetailActivity"
    android:parentActivityName=".Activities.MainActivity">
    <meta-data
      android:name="android.support.PARENT_ACTIVITY"
      android:value=".Activities.MainActivity" />
</activity>

2) Use TaskStackBuilder to create a Pending Intent.

public PendingIntent getPendingIntent(Intent intent){

    TaskStackBuilder taskStackBuilder = TaskStackBuilder
                                            .create(this);
    taskStackBuilder.addNextIntentWithParentStack(intent);
    PendingIntent pendingIntent =  taskStackBuilder
             .getPendingIntent(0,PendingIntent.FLAG_UPDATE_CURRENT);

}

You are all set. Now just pass this Pending intent to create Notifications.

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