Android - getTargetFragment and setTargetFragment - What are they used for

Question

I tried searching but i\'m still a little lost. I usually do fragment to fragment communication through an Activity via interfaces or a BroadcastReceiver

Answer 1

i finally found out how to use setTarget in a fragment and wanted to share. its quite useful when you want to communicate from fragment to fragment.

here is an example: let's say you wanted to show a dialog and when it closes you want to do some action.

so in your fragment1 that will use the dialog you could do this:

myDialogFragment.setTargetFragment(fragment1, myDialogFragment.REQ_CODE);

and in your fragment that called the dialog you would need to override onActivityResult like this:

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    if(requestCode == CoDDialogFragment.REQ_CODE)
        exit(); //or whatever you want to do here
}

and in the myDialogFragment you could do this:

TellTargetYouGotResults(REQ_CODE);

//...
private void TellTargetYouGotResults(int code) {
    Fragment targetFragment = getTargetFragment(); // fragment1 in our case
    if (targetFragment != null) {
        targetFragment.onActivityResult(getTargetRequestCode(), code, null);
    }
}

where REQ_CODE can be any int of course . Very useful for fragment to fragment communication. but i still prefer event bus as sometimes after sending data to a target its view might have already been destroyed (incase its a fragment) and then if you try to update the view in onActivityResult you'll get a crash. so i'd say its useful to just pass data along but not update the UI unless you've done a 'add' fragment transaction and not a replace (which destroys the view but keeps state).