我已经在 android 应用程序中实现了计时器功能，我可以通过调用其他本地方法来完成计时器timerObject.cancel()。它工作完美。
但是当我尝试在onTick()特定条件下调用相同的方法时，我无法取消计时器，它会持续到计时器时间结束。
如何取消计时器？
问问题
7030 次
3 回答
5
AFAIK你不能那样做
但是 Android CountDownTimer 类有一个 Drop-in 替代方案，但您可以从 onTick 中取消它。
干得好
/*
* 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 alt.android.os;
import android.util.Log;
import android.os.Handler;
import android.os.SystemClock;
import android.os.Message;
/**
* 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;
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.
*
* Do not call it from inside CountDownTimer threads
*/
public final void cancel() {
mHandler.removeMessages(MSG);
mCancelled = true;
}
/**
* Start the countdown.
*/
public synchronized final CountDownTimer start() {
if (mMillisInFuture <= 0) {
onFinish();
return this;
}
mStopTimeInFuture = SystemClock.elapsedRealtime() + mMillisInFuture;
mHandler.sendMessage(mHandler.obtainMessage(MSG));
mCancelled = false;
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) {
final long millisLeft = mStopTimeInFuture - SystemClock.elapsedRealtime();
if (millisLeft <= 0) {
onFinish();
} else if (millisLeft < mCountdownInterval) {
// no tick, just delay until done
sendMessageDelayed(obtainMessage(MSG), millisLeft);
} else {
long lastTickStart = SystemClock.elapsedRealtime();
onTick(millisLeft);
// take into account user's onTick taking time to execute
long delay = lastTickStart + mCountdownInterval - SystemClock.elapsedRealtime();
// special case: user's onTick took more than interval to
// complete, skip to next interval
while (delay < 0) delay += mCountdownInterval;
if (!mCancelled) {
sendMessageDelayed(obtainMessage(MSG), delay);
}
}
}
}
};
}
于 2012-07-04T05:11:43.777 回答
1
查看源代码CountDownTimer很容易看出它为什么不起作用。cancel()只是从队列中删除用于计时的消息。但是在每个滴答声中调用的消息处理程序会在调用 后为下一个滴答声发布一条消息onTick()。因此，您要么必须通过例如cancel()在外部调用，要么改用 Timer 类。onTick()Handler
于 2012-07-04T05:17:05.013 回答
0
如果使用 RXJava2。这段代码可以帮助你。
public abstract class CountDownTimer {
private TimeUnit timeUnit;
private Long startValue;
private Disposable disposable;
public CountDownTimer(Long startValue,TimeUnit timeUnit) {
this.timeUnit = timeUnit;
this.startValue = startValue;
}
public abstract void onTick(long tickValue);
public abstract void onFinish();
public void start(){
io.reactivex.Observable.zip(
io.reactivex.Observable.range(0, startValue.intValue()), io.reactivex.Observable.interval(1, timeUnit), (integer, aLong) -> {
Long l = startValue-integer;
return l;
}
).subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Observer<Long>() {
@Override
public void onSubscribe(Disposable d) {
disposable = d;
}
@Override
public void onNext(Long aLong) {
onTick(aLong);
}
@Override
public void onError(Throwable e) {
e.printStackTrace();
}
@Override
public void onComplete() {
onFinish();
}
});
}
public void cancel(){
if(disposable!=null) disposable.dispose();
}
}
使用：
public class MainActivity extends AppCompatActivity {
@Override protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.start_activity);
new CountDownTimer(10L, TimeUnit.SECONDS) {
@Override
public void onTick(long tickValue) {
Log.d("CountDown", "Remaining: " + tickValue);
// cancel();
}
@Override
public void onFinish() {
Log.d("CountDown", "The End!! ");
}
}.start();
}
}
代码的所有者https://gist.github.com/chemickypes/fa3b7fc5b5a00a3ce37fee5815018702
于 2018-06-24T12:28:57.187 回答