//取消當(dāng)前任務(wù)
public final void cancel ()
//當(dāng)前任務(wù)完成的時候回調(diào)
public abstract void onFinish ()
//當(dāng)前任務(wù)每完成一次倒計時間隔時間時回調(diào)
public abstract void onTick (long millisUntilFinished)
//開始當(dāng)前任務(wù)
public final CountDownTimer start ()