android CountDownTimer - 刻度之间的额外毫秒延迟

Question

从我的观察来看,滴答之间的android CountDownTimer countDownInterval恰好不准确,countDownInterval通常比指定的时间长几毫秒.我的特定应用程序中的countDownInterval是1000毫秒,只需一秒钟倒计时一定时间.

由于这个延长的滴答声,我最终得到的滴答数减少了当倒计时器运行足够长时间,这会缩短所显示的倒计时时间(当有足够的额外ms总结时,在UI级别上发生2秒的步骤)

查看CountDownTimer的来源似乎可以扭曲它,以便纠正这种不必要的不​​准确性,但我想知道在java/android世界中是否已经有更好的CountDownTimer可用.

感谢所有指针的好友......

Answer 1

改写

正如你所说,你也注意到下一次进入onTick()是从上一次onTick()运行的时间计算出来的,这会在每次滴答时引入一个小错误.我更改了CountDownTimer源代码,onTick()从开始时间开始以指定的间隔调用每个源代码.

我在CountDownTimer框架上构建它,因此将源代码剪切并粘贴到项目中,并为类提供唯一的名称.(我称之为MoreAccurateTimer.)现在进行一些更改:

1. 添加一个新的类变量:

   private long mNextTime;
   

2. 变化start():

   public synchronized final MoreAccurateTimer start() {
       if (mMillisInFuture <= 0) {
           onFinish();
           return this;
       }
   
       mNextTime = SystemClock.uptimeMillis();
       mStopTimeInFuture = mNextTime + mMillisInFuture;
   
       mNextTime += mCountdownInterval;
       mHandler.sendMessageAtTime(mHandler.obtainMessage(MSG), mNextTime);
       return this;
   }
   

3. 更改处理程序handlerMessage():

   @Override
   public void handleMessage(Message msg) {
       synchronized (MoreAccurateTimer.this) {
           final long millisLeft = mStopTimeInFuture - SystemClock.uptimeMillis();
   
           if (millisLeft <= 0) {
               onFinish();
           } else {
               onTick(millisLeft);
   
               // Calculate next tick by adding the countdown interval from the original start time
               // If user's onTick() took too long, skip the intervals that were already missed
               long currentTime = SystemClock.uptimeMillis();
               do {
                   mNextTime += mCountdownInterval;
               } while (currentTime > mNextTime);
   
               // Make sure this interval doesn't exceed the stop time
               if(mNextTime < mStopTimeInFuture)
                   sendMessageAtTime(obtainMessage(MSG), mNextTime);
               else
                   sendMessageAtTime(obtainMessage(MSG), mStopTimeInFuture);
           }
       }
   }