From 0b5140d9db49c3121a8cbbcb455b575a0ab13023 Mon Sep 17 00:00:00 2001 From: Maksym Plencler Date: Wed, 30 Mar 2016 20:48:44 +0200 Subject: [PATCH] Fix fragment injection NPE Fixes NPE exception thrown during injection of fragment in onCreate(Bundle) when parent activity is being recreated by the system (due to eg. long inactivity) and it's dagger component is not fully initialized. --- .../view/fragment/BaseFragment.java | 70 ++++++++++++++++++- .../view/fragment/UserDetailsFragment.java | 10 +-- .../view/fragment/UserListFragment.java | 12 ++-- 3 files changed, 79 insertions(+), 13 deletions(-) diff --git a/presentation/src/main/java/com/fernandocejas/android10/sample/presentation/view/fragment/BaseFragment.java b/presentation/src/main/java/com/fernandocejas/android10/sample/presentation/view/fragment/BaseFragment.java index a312d134..2cce11bf 100644 --- a/presentation/src/main/java/com/fernandocejas/android10/sample/presentation/view/fragment/BaseFragment.java +++ b/presentation/src/main/java/com/fernandocejas/android10/sample/presentation/view/fragment/BaseFragment.java @@ -6,6 +6,9 @@ package com.fernandocejas.android10.sample.presentation.view.fragment; import android.app.Fragment; +import android.os.Bundle; +import android.util.Log; +import android.view.View; import android.widget.Toast; import com.fernandocejas.android10.sample.presentation.internal.di.HasComponent; @@ -13,6 +16,32 @@ * Base {@link android.app.Fragment} class for every fragment in this application. */ public abstract class BaseFragment extends Fragment { + + private boolean mIsInjected = false; + + @Override public void onCreate(Bundle savedInstanceState) { + super.onCreate(savedInstanceState); + try { + mIsInjected = onInjectView(); + } catch (IllegalStateException e) { + Log.e(e.getClass().getSimpleName(), e.getMessage()); + mIsInjected = false; + } + } + + @Override public void onViewCreated(View view, Bundle savedInstanceState) { + super.onViewCreated(view, savedInstanceState); + if (mIsInjected) onViewInjected(savedInstanceState); + } + + @Override public void onActivityCreated(Bundle savedInstanceState) { + super.onActivityCreated(savedInstanceState); + if (!mIsInjected) { + mIsInjected = onInjectView(); + if (mIsInjected) onViewInjected(null); + } + } + /** * Shows a {@link android.widget.Toast} message. * @@ -24,9 +53,46 @@ protected void showToastMessage(String message) { /** * Gets a component for dependency injection by its type. + * + * @throws IllegalStateException if component has not been initialized yet. */ @SuppressWarnings("unchecked") - protected C getComponent(Class componentType) { - return componentType.cast(((HasComponent) getActivity()).getComponent()); + protected C getComponent(Class componentType) throws IllegalStateException { + C component = componentType.cast(((HasComponent) getActivity()).getComponent()); + if (component == null) { + throw new IllegalStateException(componentType.getSimpleName() + " has not been initialized yet."); + } + return component; + } + + /** + * Called to do an optional injection. This will be called on {@link #onCreate(Bundle)} and if + * an exception is thrown or false returned, on {@link #onActivityCreated(Bundle)} again. + * Within this method get the injection component and inject the view. Based on returned value + * {@link #onViewInjected(Bundle)} will be called. Check {@link #onViewInjected(Bundle)} + * documentation for more info. + * + * @return True, if injection was successful, false otherwise. Returns false by default. + * @throws IllegalStateException If there is a failure in getting injection component or + * injection process itself. This can occur if activity holding + * component instance has been killed by the system and has not + * been initialized yet. + */ + protected boolean onInjectView() throws IllegalStateException { + // Return false by default. + return false; + } + + /** + * Called when the fragment has been injected and the field injected can be initialized. This + * will be called on {@link #onViewCreated(View, Bundle)} if {@link #onInjectView()} returned + * true when executed on {@link #onCreate(Bundle)}, otherwise it will be called on + * {@link #onActivityCreated(Bundle)} if {@link #onInjectView()} returned true right before. + * + * @param savedInstanceState If non-null, this fragment is being re-constructed + * from a previous saved state as given here. + */ + protected void onViewInjected(Bundle savedInstanceState) { + // Intentionally left empty. } } diff --git a/presentation/src/main/java/com/fernandocejas/android10/sample/presentation/view/fragment/UserDetailsFragment.java b/presentation/src/main/java/com/fernandocejas/android10/sample/presentation/view/fragment/UserDetailsFragment.java index e5c51334..c55867e8 100644 --- a/presentation/src/main/java/com/fernandocejas/android10/sample/presentation/view/fragment/UserDetailsFragment.java +++ b/presentation/src/main/java/com/fernandocejas/android10/sample/presentation/view/fragment/UserDetailsFragment.java @@ -43,20 +43,20 @@ public UserDetailsFragment() { setRetainInstance(true); } - @Override public void onCreate(Bundle savedInstanceState) { - super.onCreate(savedInstanceState); + @Override protected boolean onInjectView() throws IllegalStateException { this.getComponent(UserComponent.class).inject(this); + return true; } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, - Bundle savedInstanceState) { + Bundle savedInstanceState) { final View fragmentView = inflater.inflate(R.layout.fragment_user_details, container, false); ButterKnife.bind(this, fragmentView); return fragmentView; } - @Override public void onViewCreated(View view, Bundle savedInstanceState) { - super.onViewCreated(view, savedInstanceState); + @Override protected void onViewInjected(Bundle savedInstanceState) { + super.onViewInjected(savedInstanceState); this.userDetailsPresenter.setView(this); if (savedInstanceState == null) { this.loadUserDetails(); diff --git a/presentation/src/main/java/com/fernandocejas/android10/sample/presentation/view/fragment/UserListFragment.java b/presentation/src/main/java/com/fernandocejas/android10/sample/presentation/view/fragment/UserListFragment.java index 6da47c9a..e0ead954 100644 --- a/presentation/src/main/java/com/fernandocejas/android10/sample/presentation/view/fragment/UserListFragment.java +++ b/presentation/src/main/java/com/fernandocejas/android10/sample/presentation/view/fragment/UserListFragment.java @@ -60,21 +60,21 @@ public UserListFragment() { } } - @Override public void onCreate(Bundle savedInstanceState) { - super.onCreate(savedInstanceState); + @Override protected boolean onInjectView() throws IllegalStateException { this.getComponent(UserComponent.class).inject(this); + return true; } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, - Bundle savedInstanceState) { + Bundle savedInstanceState) { final View fragmentView = inflater.inflate(R.layout.fragment_user_list, container, false); ButterKnife.bind(this, fragmentView); - setupRecyclerView(); return fragmentView; } - @Override public void onViewCreated(View view, Bundle savedInstanceState) { - super.onViewCreated(view, savedInstanceState); + @Override protected void onViewInjected(Bundle savedInstanceState) { + super.onViewInjected(savedInstanceState); + this.setupRecyclerView(); this.userListPresenter.setView(this); if (savedInstanceState == null) { this.loadUserList();