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March 8, 2019 05:30
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Utility method for getting the appropriate parent of a Fragment for a given callback interface.
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| import android.support.v4.app.Fragment; | |
| import android.support.v4.app.FragmentActivity; | |
| public class FragmentUtils { | |
| /** | |
| * @param frag | |
| * The Fragment whose parent is to be found | |
| * @param callbackInterface | |
| * The interface class that the parent should implement | |
| * @return The parent of frag that implements the callbackInterface or null | |
| * if no such parent can be found | |
| */ | |
| @Nullable | |
| public static <T> T getParent(@NonNull Fragment frag, @NonNull Class<T> callbackInterface) { | |
| Fragment parentFragment = fragment.getParentFragment(); | |
| if (parentClass.isInstance(parentFragment)) { | |
| //Checked by runtime methods | |
| //noinspection unchecked | |
| return (T) parentFragment; | |
| } else if (parentClass.isInstance(fragment.getActivity())) { | |
| //Checked by runtime methods | |
| //noinspection unchecked | |
| return (T) fragment.getActivity(); | |
| } | |
| return null; | |
| } | |
| } |
Could you give this gist an explicit license? Maybe Apache 2.0?
Nice utillity! Btw, you don't need to explicitly check if the parentFragment and activity are null. Class#isInstance(...) returns false if the argument is null.
When is the best place to call this on a a fragment recreate (e.g. on a rotation)? Obviously if you know you are child of an activity you can use the onAttach() lifecycle call back.
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Maybe change to while to check if grandparent of parent fragment implements callback?