Two classes in Android let you no longer have to implement onActivityResult of

Preface

When we know that fragment can only receive callbacks requested by itself, we can use it to decouple the logic of onActivityResult in activity. In general, if there are multiple callback results in one activity, there will be various case judgments in onActivityResult (), and this design also interrupts streaming writing. Then we simply build an fragment without UI as an accurate receiver, so that we can never write onActivityResult () again.

Fragment:

/**
 * @author Kale
 * @date 2018/4/13
 */
public class OnActResultEventDispatcherFragment extends Fragment {

 public static final String TAG = "on_act_result_event_dispatcher";

 private SparseArray<ActResultRequest.Callback> mCallbacks = new SparseArray<>();

 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setRetainInstance(true);
 }

 public void startForResult(Intent intent, ActResultRequest.Callback callback) {
  mCallbacks.put(callback.hashCode(), callback);
  startActivityForResult(intent, callback.hashCode());
 }

 @Override
 public void onActivityResult(int requestCode, int resultCode, Intent data) {
  super.onActivityResult(requestCode, resultCode, data);

  ActResultRequest.Callback callback = mCallbacks.get(requestCode);
  mCallbacks.remove(requestCode);

  if (callback != null) {
   callback.onActivityResult(resultCode, data);
  }
 }
}

Request encapsulation class:

public class ActResultRequest {

 private OnActResultEventDispatcherFragment fragment;

 public ActResultRequest(Activity activity) {
  fragment = getEventDispatchFragment(activity);
 }

 private OnActResultEventDispatcherFragment getEventDispatchFragment(Activity activity) {
  final FragmentManager fragmentManager = activity.getFragmentManager();

  OnActResultEventDispatcherFragment fragment = findEventDispatchFragment(fragmentManager);
  if (fragment == null) {
   fragment = new OnActResultEventDispatcherFragment();
   fragmentManager
     .beginTransaction()
     .add(fragment, OnActResultEventDispatcherFragment.TAG)
     .commitAllowingStateLoss();
   fragmentManager.executePendingTransactions();
  }
  return fragment;
 }

 private OnActResultEventDispatcherFragment findEventDispatchFragment(FragmentManager manager) {
  return (OnActResultEventDispatcherFragment) manager.findFragmentByTag(OnActResultEventDispatcherFragment.TAG);
 }

 public void startForResult(Intent intent, Callback callback) {
  fragment.startForResult(intent, callback);
 }

 public interface Callback {

  void onActivityResult(int resultCode, Intent data);
 }
}

Code for sending request and listening request:

Intent intent = new Intent(this, SecondActivity.class);

request.startForResult(intent, new ActResultRequest.Callback() {
 @Override
 public void onActivityResult(int resultCode, Intent data) {
  Toast.makeText(MainActivity.this, "" + resultCode, Toast.LENGTH_SHORT).show();
 }
});

Digression:

The latest support package has solved the problem that the inner fragment can't receive the result when fragment is nested. Please update the dependency in time.

Summarize