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
17package com.android.contacts.common.util;
18
19import android.os.AsyncTask;
20
21import java.lang.ref.WeakReference;
22
23public abstract class WeakAsyncTask<Params, Progress, Result, WeakTarget> extends
24        AsyncTask<Params, Progress, Result> {
25    protected WeakReference<WeakTarget> mTarget;
26
27    public WeakAsyncTask(WeakTarget target) {
28        mTarget = new WeakReference<WeakTarget>(target);
29    }
30
31    /** {@inheritDoc} */
32    @Override
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
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
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
60    protected void onPreExecute(WeakTarget target) {
61        // No default action
62    }
63
64    protected abstract Result doInBackground(WeakTarget target, Params... params);
65
66    protected void onPostExecute(WeakTarget target, Result result) {
67        // No default action
68    }
69}
70