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
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
|
/*
* Copyright (C) 2008 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 android.os;
/**
* Schedule a countdown until a time in the future, with
* regular notifications on intervals along the way.
*
* Example of showing a 30 second countdown in a text field:
*
* <pre class="prettyprint">
* new CountDownTimer(30000, 1000) {
*
* public void onTick(long millisUntilFinished) {
* mTextField.setText("seconds remaining: " + millisUntilFinished / 1000);
* }
*
* public void onFinish() {
* mTextField.setText("done!");
* }
* }.start();
* </pre>
*
* The calls to {@link #onTick(long)} are synchronized to this object so that
* one call to {@link #onTick(long)} won't ever occur before the previous
* callback is complete. This is only relevant when the implementation of
* {@link #onTick(long)} takes an amount of time to execute that is significant
* compared to the countdown interval.
*/
public abstract class CountDownTimer {
/**
* Millis since epoch when alarm should stop.
*/
private final long mMillisInFuture;
/**
* The interval in millis that the user receives callbacks
*/
private final long mCountdownInterval;
private long mStopTimeInFuture;
/**
* boolean representing if the timer was cancelled
*/
private boolean mCancelled = false;
/**
* @param millisInFuture The number of millis in the future from the call
* to {@link #start()} until the countdown is done and {@link #onFinish()}
* is called.
* @param countDownInterval The interval along the way to receive
* {@link #onTick(long)} callbacks.
*/
public CountDownTimer(long millisInFuture, long countDownInterval) {
mMillisInFuture = millisInFuture;
mCountdownInterval = countDownInterval;
}
/**
* Cancel the countdown.
*/
public synchronized final void cancel() {
mCancelled = true;
mHandler.removeMessages(MSG);
}
/**
* Start the countdown.
*/
public synchronized final CountDownTimer start() {
mCancelled = false;
if (mMillisInFuture <= 0) {
onFinish();
return this;
}
mStopTimeInFuture = SystemClock.elapsedRealtime() + mMillisInFuture;
mHandler.sendMessage(mHandler.obtainMessage(MSG));
return this;
}
/**
* Callback fired on regular interval.
* @param millisUntilFinished The amount of time until finished.
*/
public abstract void onTick(long millisUntilFinished);
/**
* Callback fired when the time is up.
*/
public abstract void onFinish();
private static final int MSG = 1;
// handles counting down
private Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
synchronized (CountDownTimer.this) {
if (mCancelled) {
return;
}
final long millisLeft = mStopTimeInFuture - SystemClock.elapsedRealtime();
if (millisLeft <= 0) {
onFinish();
} else {
long lastTickStart = SystemClock.elapsedRealtime();
onTick(millisLeft);
// take into account user's onTick taking time to execute
long lastTickDuration = SystemClock.elapsedRealtime() - lastTickStart;
long delay;
if (millisLeft < mCountdownInterval) {
// just delay until done
delay = millisLeft - lastTickDuration;
// special case: user's onTick took more than interval to
// complete, trigger onFinish without delay
if (delay < 0) delay = 0;
} else {
delay = mCountdownInterval - lastTickDuration;
// special case: user's onTick took more than interval to
// complete, skip to next interval
while (delay < 0) delay += mCountdownInterval;
}
sendMessageDelayed(obtainMessage(MSG), delay);
}
}
}
};
}
|
