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Let’s say we have fragment which is used for login.
So we need to use this fragment wherever login action is necessary. We also need to get a callback from that fragment from where it created
We know that from an activity if we need to listen to call back from the fragment we need to implement an interface and use that interface in the fragment to trigger a callback to the activity.
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@Override public void onAttach(Context context) { super.onAttach(context); try { listener = (LoginListener) context; } catch (ClassCastException e) { throw new ClassCastException(context.toString() + " must implement OnSelectImageListener"); } } |
but if we need to use this fragment in both activity and fragment we need to add a method in that fragment called setlistener(Callback)
whenever we open the fragment from other fragments we need to call that setlistener(this) method to initiate callback and implement that callback in the fragment where we expect to receive the callback.
and we need to change the on attach method a little bit like
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@Override public void onAttach(Context context) { super.onAttach(context); try { if (listener==null) {//we added callback manually if listener!=null listener = (LoginListener) context; } } catch (ClassCastException e) { throw new ClassCastException(context.toString() + " must implement OnSelectImageListener"); } } |
Now it will return call back in wherever we want. In a activity or in a fragment.
For fragment, we only need to set the callback manually.
