在Android中同时启动两个(或更多)功能

Question

我正在为Android 2.2设计一个天文台/倒数计时器应用程序,并希望按一下按钮同时启动计时器和计时器.因此,理想情况下,我想在秒(时间)都记时计和定时器在同一个实例来改变.(即使计时器正在计数,计时器也会倒计时).由于我使用Android提供的计时器和计时器功能,当用户按下"开始"按钮时,我编写了以下代码

private boolean mStartPressedOnce = false;
long mTimeWhenStopped = 0;
Chronometer mChronometer;   
MyCounter mCounter;
...
@Override
public void onClick(View v) {
    switch (v.getId()) {
    case R.id.StartButton:
        // Perform some initialization for the chronometer depending
        // on the button press
        if (mStartPressedOnce == false) {
            mChronometer.setBase(SystemClock.elapsedRealtime());
        } else {
            mChronometer.setBase(SystemClock.elapsedRealtime() + mTimeWhenStopped);
        }

        // Perform the initialization for the timer
        mCounter = new MyCount(45000, 1000);

        // Fire up the chronometer  
        mChronometer.start();

        // Fire up the timer
        mCounter.start();
        break;

        case R.id.ResetButton:
            // Reset the chronometer  
            mChronometer.setBase(SystemClock.elapsedRealtime());
            mTimeWhenStopped = 0;
            break;

        case case R.id.StopButton:
            mStartPressedOnce = true;
            // Stop the chronometer 
            mTimeWhenStopped = mChronometer.getBase() - SystemClock.elapsedRealtime();
            mChronometer.stop();
            break;
    }

... 

public class MyCounter extends CountDownTimer {

    @Override
    public MyCount(long millisInFuture, long countDownInterval) {
        super(millisInFuture, countDownInterval);
    }

    @Override
    public void onFinish() {        
        // Nothing to do here
    }

    @Override
    public void onTick(long millisUntilFinished) {
        long seconds = (long) (millisUntilFinished / 1000);
        long minutes = (long) ((millisUntilFinished / 1000) / 60);
        long hours = (long) (((millisUntilFinished / 1000) / 60) / 60);

        // Do some formatting to make seconds, minutes and hours look pretty    

        // Update the timer TextView            
       (TextView) findViewById(R.id.CountDownTimerTextView))
           .setText(hours + ":" + minutes + ":" + seconds);
    }
}

虽然看起来计时器和计时器上的秒数最初是同步的,但是在很短的时间之后,它们似乎会熄灭,并且两者的第二次更新都会在不同的时间发生.

想知道我能做些什么来解决这个问题.我确实遇到过 - 并阅读了这个帖子

同时运行多个AsyncTasks - 不可能？

我意识到可能需要进行设计更改,但我不确定需要做什么.

编辑:计时器和计时器的包含类型以及使用天文台计算时间的方法 - 每个jolivier和njzk2的建议

Answer 1

因此，在思考了一段时间并放弃jolivier与我们慷慨分享的建议之后，我意识到存在一个名为 的方法，onChronometerTick每次有计时器滴答时（在本例中为每秒）都会调用该方法。因此，我想到每次调用该方法时从计数器中减去 1000 毫秒，并相应地更新计时器显示。我完全摆脱了Android计时器部分（CountDownTimer）。我认为这是让两个显示器同时更新的好方法。这也是一个定时器的简单实现。

我很高兴地报告，它似乎运作良好。计时器和天文台显示确实同时更新。所以，原来的问题看起来已经有了答案。不幸的是，我在计时器前端遇到了一个相差两个错误，我用一个丑陋的黑客修复了它。我正在发布到目前为止我所拥有的内容。欢迎任何有关如何修复黑客或改进代码的建议。请注意，我对代码进行了注释，以使其易于理解所做的事情。

编辑 bug：我注意到的另一件事是，大约 10 分钟后，计时器和计时器关闭了一秒钟。更准确地说，计时器落后天文钟一秒。尚不清楚为什么会发生这种情况。

private boolean mStartPressedOnce = false;
long mTimeWhenStopped = 0;
Chronometer mChronometer;   
long millisUntilFinished = 0;
boolean firstPassOver = false;
int counter = 0;
...
@Override
public void onClick(View v) {
    switch (v.getId()) {
    case R.id.StartButton:
        // Perform some initialization for the chronometer depending
        // on the button press
        if (mStartPressedOnce == false) {
            mChronometer.setBase(SystemClock.elapsedRealtime());
        } else {
            mChronometer.setBase(SystemClock.elapsedRealtime() + mTimeWhenStopped);
        }

        // Fire up the chronometer  
        mChronometer.start();
        break;

        case R.id.ResetButton:
            // Reset the chronometer  
            mChronometer.setBase(SystemClock.elapsedRealtime());
            mTimeWhenStopped = 0;
            break;

        case case R.id.StopButton:
            mStartPressedOnce = true;
            // Stop the chronometer 
            mTimeWhenStopped = mChronometer.getBase() - SystemClock.elapsedRealtime();
            mChronometer.stop();
            break;
    }

... 

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.stop_watch);

    mChronometer = (Chronometer) findViewById(R.id.StopWatchTextView);

    // Initialize the number of milliseconds before the timer expires (
    // set the timer) - in this case to 46 seconds
    millisUntilFinished = 46000;

    // Display how many seconds remain before the timer expires
    ((TextView) findViewById(R.id.CountDownTimerTextView)).setText(hours
            + ":" + minutes + ":" + millisUntilFinished / 1000);

    // In line with the suggestion provided by  jolivier - make the timer
    // the slave and  update its display every time the chronometer 
    // ticks        
    mChronometer
            .setOnChronometerTickListener(new Chronometer.OnChronometerTickListener() {

                @Override
                public void onChronometerTick(Chronometer chronometer) {

                    // Update the display for the chronometer
                    CharSequence text = chronometer.getText();                  
                    chronometer.setText(text);

                    // Update the display for the timer                 
                    // !!! BUG !!!
                    // Looks like onChronometerTick is called at the 0th second
                    // and this causes an off by two error if a count down timer
                    // is being implemented. Fixed it with this hack. There's gotta
                    // be a more elegant solution, though.
                    if(counter >= 2) {
                        millisUntilFinished1 = millisUntilFinished1 - 1000;
                        counter = 2;
                    }
                    counter++;

                    if (millisUntilFinished >= 0) {

                        long seconds = (long) (millisUntilFinished / 1000);
                        long minutes = (long) ((millisUntilFinished / 1000) / 60);
                        long hours = (long) (((millisUntilFinished / 1000) / 60) / 60);

                        // Do some formatting to make seconds, minutes and hours look pretty    

                        // Update the timer TextView     
                        ((TextView) findViewById(R.id.CountDownTimerTextView))
                                .setText(hours + ":" + minutes + ":"
                                        + seconds);
                        }
                    }

    });
    // Other code
    ...
}