java - 如何计算到设定时间的剩余时间

Question

我想在 Android(Java)中创建一个类似闹钟的应用程序，我想计算剩余的小时数和分钟数。当我将闹钟设置为凌晨 1:00 时。我现在的时间是晚上 20:00，它会告诉我“5 小时后会响起警报”，但它会在 19 小时后告诉我，如何解决。

Toast.makeText(this, "Hours: " + (calendar.getTime().getHours() - timePicker.getCurrentHour()) + "Minutes: " + (calendar.getTime().getMinutes() - timePicker.getCurrentMinute()) , Toast.LENGTH_SHORT).show();

Answer 1

尝试这样的事情:

    Calendar cal = Calendar.getInstance();

    int hrs = cal.get(Calendar.HOUR_OF_DAY);

    Calendar alCal = Calendar.getInstance();
    alCal.set(Calendar.HOUR_OF_DAY, timePicker.getCurrentHour());

    alCal.set(Calendar.MINUTE, timePicker.getCurrentMinute());

    if(timePicker.getCurrentHour() < hrs){
        alCal.add(Calendar.DAY_OF_MONTH, 1);
    }

    long diff = alCal.getTimeInMillis() - cal.getTimeInMillis();

    long leftHrs = (diff / (60 * 60 * 1000));
    long leftMin = (diff / (60 * 1000)) - (leftHrs * 60);

    // Output
    Toast.makeText(this,"Hours: "+leftHrs+"Minutes: "+leftMin,Toast.LENGTH_SHORT).show();