Question

I am working with multiple Fragments under Android and am confused on how to send and receive data from embedded apps.

For a simple explanation, I have a ListFragment and a MapFragment using the method explained here. This means that the List lives in the ListFragment class, however the MapActivity is an Activity that is called under the LocalActivityManagerFragment.

Everything works on the individual Fragments: Lists of waypoints, waypoints and current location implemented on the MapFragment. I also understand how to use getFragmentManager() to get individual Fragments and use their events. However, I cannot use this method to access a function under MapActivity. How can I use a command such as goToLocation (created under MapActivity) if I click on an item on the ListView, if I can’t simply use getFragmentManager??

Answer 1

For communication between a Fragment and an activity:

Activity > Fragment:

Call on the public methods of the fragment using this.

TestFragment testFrag = (TestFragment) getFragmentManager().getFragmentById(R.id.testfragment);

if(testFrag != null && testFrag.isAdded())
    testFrag.testMethod("Test");

Fragment > Activity

To send messages to the activity you need to use an interface so in the fragments class add this: (Not in any method)

public interface testInterface{
    public void testMethod(String test);
}

testInterface mCallback;

@Override
public void onAttact(Activity a){
    try{
        mCallback = (testInterface) a;
    }catch(Exception e){
        //TODO
    }
}

then in any method you can go and call this:

mCallback.testMethod("hello");

then for the activity make it so it implements testInterface and import the interface

and then have this method in the activity

@Override
public void testMethod(String testString){

}

🙂 Just ask for anything more.

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Edit

From my first read of your question I thought this is what you wanted sorry, could still cover what you wanted.

I think what your asking for is just a onItemClick method right?

so in the interface you could have

public void onItemClicked(AdapterView<?> parent, View view, int position, long id);

then when onItemClick has been called in the fragment you can use this in it

mCallback.onItemClicked(parent, view, position, id);

and then in the activity, given its implementing the interface you can have

@Override
public void onItemClicked(AdapterView<?> parent, View view, int position, long id){

}