Android Application Development For Dummies, 2nd Edition

Working with Fragments on Tablet Applications

You create a new activity for your table app, and now you have to add fragments to it. There’s no need to write new fragments to use with the tablet activity. However, you need to make some changes to your fragments to make sure they work properly in this new environment.

Communicating with fragments

Allowing fragments to communicate with each other by using activities as their intermediaries is a common best practice when using fragments. Visit http://developer.android.com/guide/components/fragments.html for more details on this important pattern. Anytime you need to interact with another fragment, you should always use a method in the fragment’s activity rather than access the other fragment directly. The only time it makes sense to access one fragment from another is when you know that you won’t need to reuse your fragment in another activity. However, life is always full of surprises — you should almost always write fragments assuming that you’ll reuse them rather than hard-code them to each other.

Communicating between fragments

If you try to add a task with your tablet application, it doesn’t show the edit fragment next to the list fragment as you expect, but instead opens a new activity to add a task.

The reason that your app opens the edit fragment in a new activity, rather than adjacent to the list fragment, is that it’s still doing exactly what it was told. It’s still executing the old phone behavior, which is to start ...