少年意气强不羁，虎胁插翼白日飞。这篇文章主要讲述当活动不在前面时，在Android中暂停CountDownTimer相关的知识，希望能为你提供帮助。
我有一个使用从10开始倒计时的CountDownTimer的活动。当活动不再处于焦点时如何暂停该计时器，如用户接到电话或其他内容，然后在用户返回时恢复计时器活动？这甚至可能吗？
答案我会在onTick处理程序中添加一些东西来保存你的类中的计时器进度（剩下的毫秒数）。
在onPause（）方法中为活动调用计时器上的cancel（）。
在活动的onResume（）方法中，创建一个新的计时器，保留剩余的毫秒数。
另一答案您可以使用pause()暂停计时器，稍后通过调用start()启动或恢复countDownTimer。
/**
* This class uses the native CountDownTimer to
* create a timer which could be paused and then
* started again from the previous point. You can
* provide implementation for onTick() and onFinish()
* then use it in your projects.
*/
public abstract class CountDownTimerPausable {
long millisInFuture = 0;
long countDownInterval = 0;
long millisRemaining =0;
CountDownTimer countDownTimer = null;
boolean isPaused = true;
public CountDownTimerPausable(long millisInFuture, long countDownInterval) {
super();
this.millisInFuture = millisInFuture;
this.countDownInterval = countDownInterval;
this.millisRemaining = this.millisInFuture;
}
private void createCountDownTimer(){
countDownTimer = new CountDownTimer(millisRemaining,countDownInterval) {@Override
public void onTick(long millisUntilFinished) {
millisRemaining = millisUntilFinished;
CountDownTimerPausable.this.onTick(millisUntilFinished);
}@Override
public void onFinish() {
CountDownTimerPausable.this.onFinish();
}
};
}
/**
* 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();
/**
* Cancel the countdown.
*/
public final void cancel(){
if(countDownTimer!=null){
countDownTimer.cancel();
}
this.millisRemaining = 0;
}
/**
* Start or Resume the countdown.
* @return CountDownTimerPausable current instance
*/
public synchronized final CountDownTimerPausable start(){
if(isPaused){
createCountDownTimer();
countDownTimer.start();
isPaused = false;
}
return this;
}
/**
* Pauses the CountDownTimerPausable, so it could be resumed(start)
* later from the same point where it was paused.
*/
public void pause()throws IllegalStateException{
if(isPaused==false){
countDownTimer.cancel();
} else{
throw new IllegalStateException("CountDownTimerPausable is already in pause state, start counter before pausing it.");
}
isPaused = true;
}
public boolean isPaused() {
return isPaused;
}
}
另一答案无需创建新的Timer，只需设置millisUntilFinished = total即可。例如
private CountDownTimer cdTimer;
private long total = 30000;
...
toggleButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View view){
if(toggleButton.isChecked()) {
startCountDownTimer();
}else{
cdTimer.cancel();
}
}
});
...private void startCountDownTimer() {
cdTimer = new CountDownTimer(total, 1000) {
public void onTick(long millisUntilFinished) {
//update total with the remaining time left
total = millisUntilFinished;
nTimeLabel.setText("seconds remaining: " +millisUntilFinished/ 1000);
}
public void onFinish() {
nTimeLabel.setText("done!");
}
}.start();
}
另一答案这一定是你正在寻找的。来源是this Gist.
package alt.android.os;
import android.os.Handler;
import android.os.SystemClock;
import android.os.Message;
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 long mPauseTime;
private boolean mCancelled = false;
private boolean mPaused = 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;
mPaused = false;
return this;
}/**
* Pause the countdown.
*/
public long pause() {
mPauseTime = mStopTimeInFuture - SystemClock.elapsedRealtime();
mPaused = true;
return mPauseTime;
}/**
* Resume the countdown.
*/
public long resume() {
mStopTimeInFuture = mPauseTime + SystemClock.elapsedRealtime();
mPaused = false;
mHandler.sendMessage(mHandler.obtainMessage(MSG));
return mPauseTime;
}/**
* 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 (!mPaused) {
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);
}
}
}
}
}
};
}
另一答案【当活动不在前面时，在Android中暂停CountDownTimer】你可以尝试使用Hourglass
Hourglass hourglass = new Hourglass(50000, 1000) {
@Override
public void onTimerTick(long timeRemaining) {
// Update UI
Toast.show(MainActivity.this, String.valueOf(timeRemaining), Toast.LENGTH_SHORT).show();
}@Override
public void onTimerFinish() {
// Timer finished
Toast.show(MainActivity.this, "Time
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