| /* |
| * Copyright 2020 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package androidx.activity.contextaware; |
| |
| import android.content.Context; |
| import android.os.Bundle; |
| |
| import androidx.annotation.NonNull; |
| import androidx.annotation.Nullable; |
| |
| import java.util.Set; |
| import java.util.concurrent.CopyOnWriteArraySet; |
| |
| /** |
| * Helper class for implementing {@link ContextAware}. Classes using this helper should |
| * call {@link #addOnContextAvailableListener(OnContextAvailableListener)} and |
| * {@link #removeOnContextAvailableListener(OnContextAvailableListener)} as the respective |
| * methods of {@link ContextAware} are called. |
| * <p> |
| * You must call {@link #dispatchOnContextAvailable(Context, Bundle)} once the |
| * {@link Context} is available to dispatch the callbacks to all registered listeners. |
| */ |
| public final class ContextAwareHelper { |
| |
| private final ContextAware mContextAware; |
| |
| private final Set<OnContextAvailableListener> mListeners = new CopyOnWriteArraySet<>(); |
| |
| /** |
| * Construct a new ContextAwareHelper for the given {@link ContextAware} instance. |
| * |
| * @param contextAware The ContextAware instance that listeners are being added to. |
| */ |
| public ContextAwareHelper(@NonNull ContextAware contextAware) { |
| mContextAware = contextAware; |
| } |
| |
| /** |
| * Add a new {@link OnContextAvailableListener} for receiving a callback for when |
| * this class is associated with a {@link android.content.Context}. |
| * |
| * @param listener The listener that should be added. |
| * @see #removeOnContextAvailableListener(OnContextAvailableListener) |
| */ |
| public void addOnContextAvailableListener(@NonNull OnContextAvailableListener listener) { |
| mListeners.add(listener); |
| } |
| |
| /** |
| * Remove a {@link OnContextAvailableListener} previously added via |
| * {@link #addOnContextAvailableListener(OnContextAvailableListener)}. |
| * |
| * @param listener The listener that should be removed. |
| * @see #addOnContextAvailableListener(OnContextAvailableListener) |
| */ |
| public void removeOnContextAvailableListener(@NonNull OnContextAvailableListener listener) { |
| mListeners.remove(listener); |
| } |
| |
| /** |
| * Dispatch the callback of {@link OnContextAvailableListener#onContextAvailable} to |
| * all currently added listeners. |
| * |
| * @param context The {@link Context} the {@link ContextAware} object is now associated with. |
| * @param savedInstanceState The saved instance state, if any. |
| */ |
| public void dispatchOnContextAvailable(@NonNull Context context, |
| @Nullable Bundle savedInstanceState) { |
| for (OnContextAvailableListener listener : mListeners) { |
| listener.onContextAvailable(mContextAware, context, savedInstanceState); |
| } |
| } |
| } |