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java – Android Asyntask: Use weak reference for context to avoid device rotate screen

Posted by: admin April 23, 2020 Leave a comment

Questions:

In Apress Pro Android 4 the author has said that:

[…] context of currently running activity will no longer be valid when the device is rotated. […] One approach is to use a weak reference to the activity instead of a hard reference […]

But the author just suggest this, and does not tell how it is done. Who has done this before please give me an example.

How to&Answers:

Somewhere in your AsyncTask you’ll want to pass in your activity. Then you’ll save that reference in a weak reference. Then you can dereference and use it again in onPostExecute.

Class member:

WeakReference<Activity> weakActivity;

Somewhere in AsyncTask, probably either constructor or onPreExecute:

weakActivity = new WeakReference<Activity>(activity);

In onPostExecute:

Activity activity = weakActivity.get();
if (activity != null) {
   // do your stuff with activity here
}

Answer:

Here is an example of WeakReference to store a context;

WeakReference<Context> cReference = new WeakReference<Context>(getApplicationContext());

Now we can use this weakReference to do Activity/Context related work.

Answer:

If you want to restore the previous activity, why not go for onSaveInstanceState and restore it later on.

Check this link for more details

Saving application state