| /* |
| * Copyright (C) 2015 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 com.android.tv.common; |
| |
| import android.os.Handler; |
| import android.os.Looper; |
| import android.os.Message; |
| import android.support.annotation.NonNull; |
| import java.lang.ref.WeakReference; |
| |
| /** |
| * A Handler that keeps a {@link WeakReference} to an object. |
| * |
| * <p>Use this to prevent leaking an Activity or other Context while messages are still pending. |
| * When you extend this class you <strong>MUST NOT</strong> use a non static inner class, or the |
| * containing object will still be leaked. |
| * |
| * <p>See <a href="http://android-developers.blogspot.com/2009/01/avoiding-memory-leaks.html"> |
| * Avoiding memory leaks</a>. |
| */ |
| public abstract class WeakHandler<T> extends Handler { |
| private final WeakReference<T> mRef; |
| |
| /** |
| * Constructs a new handler with a weak reference to the given referent using the provided |
| * Looper instead of the default one. |
| * |
| * @param looper The looper, must not be null. |
| * @param ref the referent to track |
| */ |
| public WeakHandler(@NonNull Looper looper, T ref) { |
| super(looper); |
| mRef = new WeakReference<>(ref); |
| } |
| |
| /** |
| * Constructs a new handler with a weak reference to the given referent. |
| * |
| * @param ref the referent to track |
| */ |
| public WeakHandler(T ref) { |
| mRef = new WeakReference<>(ref); |
| } |
| |
| /** Calls {@link #handleMessage(Message, Object)} if the WeakReference is not cleared. */ |
| @Override |
| public final void handleMessage(Message msg) { |
| T referent = mRef.get(); |
| if (referent == null) { |
| return; |
| } |
| handleMessage(msg, referent); |
| } |
| |
| /** |
| * Subclasses must implement this to receive messages. |
| * |
| * <p>If the WeakReference is cleared this method will no longer be called. |
| * |
| * @param msg the message to handle |
| * @param referent the referent. Guaranteed to be non null. |
| */ |
| protected abstract void handleMessage(Message msg, @NonNull T referent); |
| } |