Separate Back Stack for each tab in Android using Fragments

Question

I\'m trying to implement tabs for navigation in an Android app. Since TabActivity and ActivityGroup are deprecated I would like to implement it using Fragments instead.

Answer 1

Disclaimer:

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I feel this is the best place to post a related solution I have worked on for a similar type of problem that seems to be pretty standard Android stuff. It's not going to solve the problem for everyone, but it may help some.

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If the primary difference between your fragments is only the data backing them up (ie, not a lot of big layout differences), then you may not need to actually replace the fragment, but merely swap out the underlying data and refresh the view.

Here's a description of one possible example for this approach:

I have an app that uses ListViews. Each item in the list is a parent with some number of children. When you tap the item, a new list needs to open with those children, within the same ActionBar tab as the original list. These nested lists have a very similar layout (some conditional tweaks here and there perhaps), but the data is different.

This app has several layers of offspring beneath the initial parent list and we may or may not have data from the server by the time a user attempts to access any certain depth beyond the first. Because the list is constructed from a database cursor, and the fragments use a cursor loader and cursor adapter to populate the list view with list items, all that needs to happen when a click is registered is:

1) Create a new adapter with the appropriate 'to' and 'from' fields that will match new item views being added to the list and the columns returned by the new cursor.

2) Set this adapter as the new adapter for the ListView.

3) Build a new URI based on the item that was clicked and restart the cursor loader with the new URI (and projection). In this example, the URI is mapped to specific queries with the selection args passed down from the UI.

4) When the new data has been loaded from the URI, swap the cursor associated with the adapter to the new cursor, and the list will then refresh.

There is no backstack associated with this since we aren't using transactions, so you will have to either build your own, or play the queries in reverse when backing out of the hierarchy. When I tried this, the queries were fast enough that I just perform them again in oNBackPressed() up until I am at the top of hierarchy, at which point the framework takes over the back button again.

If you find yourself in a similar situation, make sure to read the docs: http://developer.android.com/guide/topics/ui/layout/listview.html

http://developer.android.com/reference/android/support/v4/app/LoaderManager.LoaderCallbacks.html

I hope this helps someone!