1 /* 2 * Copyright (C) 2010 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.gallery3d.util; 18 19 import java.util.concurrent.Callable; 20 21 // NOTE: If the Callable throws any Throwable, the result value will be null. 22 public class FutureTask<T> implements Runnable, Future<T> { 23 private static final String TAG = "FutureTask"; 24 private Callable<T> mCallable; 25 private FutureListener<T> mListener; 26 private volatile boolean mIsCancelled; 27 private boolean mIsDone; 28 private T mResult; 29 FutureTask(Callable<T> callable, FutureListener<T> listener)30 public FutureTask(Callable<T> callable, FutureListener<T> listener) { 31 mCallable = callable; 32 mListener = listener; 33 } 34 FutureTask(Callable<T> callable)35 public FutureTask(Callable<T> callable) { 36 this(callable, null); 37 } 38 cancel()39 public void cancel() { 40 mIsCancelled = true; 41 } 42 get()43 public synchronized T get() { 44 while (!mIsDone) { 45 try { 46 wait(); 47 } catch (InterruptedException t) { 48 // ignore. 49 } 50 } 51 return mResult; 52 } 53 waitDone()54 public void waitDone() { 55 get(); 56 } 57 isDone()58 public synchronized boolean isDone() { 59 return mIsDone; 60 } 61 isCancelled()62 public boolean isCancelled() { 63 return mIsCancelled; 64 } 65 run()66 public void run() { 67 T result = null; 68 69 if (!mIsCancelled) { 70 try { 71 result = mCallable.call(); 72 } catch (Throwable ex) { 73 Log.w(TAG, "Exception in running a task", ex); 74 } 75 } 76 77 synchronized(this) { 78 mResult = result; 79 mIsDone = true; 80 if (mListener != null) { 81 mListener.onFutureDone(this); 82 } 83 notifyAll(); 84 } 85 } 86 } 87