1 /*
2  * Copyright (C) 2009 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.contacts.common.util;
18 
19 import android.os.AsyncTask;
20 
21 import java.lang.ref.WeakReference;
22 
23 public abstract class WeakAsyncTask<Params, Progress, Result, WeakTarget> extends
24         AsyncTask<Params, Progress, Result> {
25     protected WeakReference<WeakTarget> mTarget;
26 
WeakAsyncTask(WeakTarget target)27     public WeakAsyncTask(WeakTarget target) {
28         mTarget = new WeakReference<WeakTarget>(target);
29     }
30 
31     /** {@inheritDoc} */
32     @Override
onPreExecute()33     protected final void onPreExecute() {
34         final WeakTarget target = mTarget.get();
35         if (target != null) {
36             this.onPreExecute(target);
37         }
38     }
39 
40     /** {@inheritDoc} */
41     @Override
doInBackground(Params... params)42     protected final Result doInBackground(Params... params) {
43         final WeakTarget target = mTarget.get();
44         if (target != null) {
45             return this.doInBackground(target, params);
46         } else {
47             return null;
48         }
49     }
50 
51     /** {@inheritDoc} */
52     @Override
onPostExecute(Result result)53     protected final void onPostExecute(Result result) {
54         final WeakTarget target = mTarget.get();
55         if (target != null) {
56             this.onPostExecute(target, result);
57         }
58     }
59 
onPreExecute(WeakTarget target)60     protected void onPreExecute(WeakTarget target) {
61         // No default action
62     }
63 
doInBackground(WeakTarget target, Params... params)64     protected abstract Result doInBackground(WeakTarget target, Params... params);
65 
onPostExecute(WeakTarget target, Result result)66     protected void onPostExecute(WeakTarget target, Result result) {
67         // No default action
68     }
69 }
70