blob: b74acb8e38c327ae41cafeb27ff28b42affee503 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
|
/*
* Copyright (C) 2016 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.documentsui;
import android.app.Activity;
import android.os.AsyncTask;
/**
* An {@link AsyncTask} that guards work with checks that a paired {@link Activity}
* is still alive. Instances of this class make no progress.
*
* <p>Use this type of task for greater safety when executing tasks that might complete
* after an Activity is destroyed.
*
* <p>Also useful as tasks can be static, limiting scope, but still have access to
* the owning class (by way the A template and the mActivity field).
*
* @template Owner Activity type.
* @template Input input type
* @template Output output type
*/
abstract class PairedTask<Owner extends Activity, Input, Output>
extends AsyncTask<Input, Void, Output> {
protected final Owner mOwner;
public PairedTask(Owner owner) {
mOwner = owner;
}
/** Called prior to run being executed. Analogous to {@link AsyncTask#onPreExecute} */
void prepare() {}
/** Analogous to {@link AsyncTask#doInBackground} */
abstract Output run(Input... input);
/** Analogous to {@link AsyncTask#onPostExecute} */
abstract void finish(Output output);
@Override
final protected void onPreExecute() {
if (mOwner.isDestroyed()) {
return;
}
prepare();
}
@Override
final protected Output doInBackground(Input... input) {
if (mOwner.isDestroyed()) {
return null;
}
return run(input);
}
@Override
final protected void onPostExecute(Output result) {
if (mOwner.isDestroyed()) {
return;
}
finish(result);
}
}
|
