Question

我想在我的Android应用程序中创建默认时间段的计时器。请帮帮我。我的应用程序正在计算课程的剩余时间。如果课程在上午8:00开始并在上午10:00结束，则当前时间为上午9:30时，计时器将显示30分钟。任何人都可以解决这个问题吗？

Answer 1

您可以使用处理程序和joda时间来计算分钟数。首先是活动中的静态内部类。静态类可防止内存泄漏。该处理程序将每分钟运行一次。

编辑：传入活动将允许您在激活中调用其他非静态方法

    public static class TimeLeftHandler extends Handler {
    private String startTime;
    private String endTime;
    private  WeakReference<MyActivity> activity

    public TimeLeftHandler(MyActivity activity, String startTime, String endTime) {
        this.startTime = startTime;
        this.endTime = endTime;
        this.activity = new WeakReference<MyActivity>(activity);
    }

    @Override
    public void handleMessage(Message msg) {
        Log.d("Timeout", "Timeout thrown from SubjectSelection");
        DateTime now = new DateTime();
        DateTimeFormatter format = DateTimeFormat.forPattern("HH:mm");
        LocalTime classStartTime = format.parseLocalTime(startTime);
        LocalTime classEndTime = format.parseLocalTime(endTime);
        DateTime nowRoundFormat = new DateTime().dayOfMonth().roundFloorCopy();
        DateTime classStart = nowRoundFormat.plusHours(classStartTime.getHourOfDay()).plusMinutes(classStartTime.getMinuteOfHour());
        DateTime classEnd = nowRoundFormat.plusHours(classEndTime.getHourOfDay()).plusMinutes(classEndTime.getMinuteOfHour());

        if (now.isAfter(classStart) && now.isBefore(classEnd)) {

            myMinutesTextView.setText("There are " + Minutes.minutesBetween(now, classEnd));
        }

        //call non-static method. 
        activity.get().nonstaticMethod();

        sendEmptyMessageDelayed(0,60000);


    }

然后活动：

public class MyActivity extends Activity { 
     private TextView myMinutesTextView;
     private TimeLeftHandler timeLeftHandler;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.mylayout);

      myMinutesTextView = (TextView) findViewById(R.id.mytextview); 
      timeLeftHandler = new TimeLeftHandler("08:00", "10:00");
    }

    @Override
    protected void onStart() { 
       //start the handler
       timeLeftHandler.sendEmptyMessage(0);

    }

    @Override
    protected void onDestroy() { 
        //clean up. 
        timeLeftHandler.removeMessages(0);



    }

    private void nonstaticMethod() { 
       //Your code. 
    }

    public static class TimeLeftHandler extends Handler {
        .....
    }


}

在build.gradle文件中使用Android Studio进行gradle构建：

dependencies {
   compile 'joda-time:joda-time:2.4'
   compile 'joda-time:joda-time:2.4'
   compile 'joda-time:joda-time:2.2'
}

在android中添加默认计时器

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