Question

现在我注意到没有办法在android中暂停CountDownTimer。我尝试在onRestart（）方法中再次启动计时器，但所有这一切都是从头开始重新启动计时器。如何为此类添加暂停功能？

这是CountDownTimer类

/*
 * 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 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;

                    sendMessageDelayed(obtainMessage(MSG), delay);
                }
            }
        }
    };
}

这是我创建的课程

package com.dose.apps.brainnoodles;

import android.content.Intent;
import android.widget.TextView;
import android.os.CountDownTimer;


public class MyMathCountDownTimer extends CountDownTimer {
    TextView textCounter;
    int score,problemsSolved;

    public MyMathCountDownTimer(TextView textCounter, long millisInFuture, long countDownInterval) {
        super(millisInFuture, countDownInterval);
        this.textCounter = textCounter;

    }

    @Override
    public void onTick (long millisUntilFinished){

        textCounter.setText(String.valueOf(millisUntilFinished / 1000));
    }

    @Override
    public void onFinish () {
        Intent gameOverIntent = new Intent(textCounter.getContext(), GameOverActivity.class);
        gameOverIntent.putExtra("scoreDoub", score);
        gameOverIntent.putExtra("problemsSolvedDoub", problemsSolved);
        textCounter.getContext().startActivity(gameOverIntent);

    }

    //Keep track of the scores
    public void recordScore(int score,int problemsSolved){
        this.problemsSolved = problemsSolved;
        this.score = score;
    }

}

Answer 1

假设倒数计时器的间隔是30秒

步骤1：保存间隔，即30000 ms

步骤2：在你的onTick（）方法中有一个从0开始递增的计数器。这将给你自定时器启动以来经过的时间量。

步骤3：当计时器暂停时，在步骤2中保存计数器

步骤4：下次取消暂停时，启动新计时器并使用

30000 - countsaved

作为计时器间隔。

对于用户来说，这似乎就像他们暂停了他们的进度一样。

需要帮助暂停CountDownTImer

1 个答案: