Question

我正在制作一个警报应用程序，该应用程序应该能够显示直到下一次警报的时间。我可以使用当前时间，小时：分钟：AM / PM值以及星期几，例如星期三凌晨3:15。我该如何计算？我唯一感兴趣的是像这样打印：07h 35m。

我所做的是，我试图将其转换为日期，然后将其转换回毫，然后进行一些数学运算，但是它不起作用，我一直得到错误的结果。

编辑：

我的问题是，我的时间由我的自定义视图设置，例如星期二凌晨3:15。我需要将其转换为最近的Date对象。例如，今天是星期二，就是凌晨2:00，我将只编辑时间，但是今天是星期五，我需要添加一些日期和时间。

Answer 1

尝试一下：

    SimpleDateFormat format = new SimpleDateFormat("hh:mm a EEE", Locale.ENGLISH);
    Calendar calendar = Calendar.getInstance();
    calendar.setTimeInMillis(format.parse("3:15 AM Tue").getTime());

    Calendar now = Calendar.getInstance();
    Calendar target = Calendar.getInstance();

    if (calendar.get(Calendar.DAY_OF_WEEK) > now.get(Calendar.DAY_OF_WEEK)) {
        target.set(Calendar.HOUR_OF_DAY, calendar.get(Calendar.HOUR_OF_DAY));
        target.set(Calendar.MINUTE, calendar.get(Calendar.MINUTE));
        target.add(Calendar.DATE, calendar.get(Calendar.DAY_OF_WEEK) - now.get(Calendar.DAY_OF_WEEK));
    } else if (calendar.get(Calendar.DAY_OF_WEEK) < now.get(Calendar.DAY_OF_WEEK)) {
        target.set(Calendar.HOUR_OF_DAY, calendar.get(Calendar.HOUR_OF_DAY));
        target.set(Calendar.MINUTE, calendar.get(Calendar.MINUTE));
        target.add(Calendar.DATE, 7 - (now.get(Calendar.DAY_OF_WEEK) - calendar.get(Calendar.DAY_OF_WEEK)));
    } else {
        if (calendar.get(Calendar.HOUR_OF_DAY) > now.get(Calendar.HOUR_OF_DAY)) {
            target.set(Calendar.HOUR_OF_DAY, calendar.get(Calendar.HOUR_OF_DAY));
            target.set(Calendar.MINUTE, calendar.get(Calendar.MINUTE));
        } else if (calendar.get(Calendar.HOUR_OF_DAY) < now.get(Calendar.HOUR_OF_DAY)) {
            target.set(Calendar.HOUR_OF_DAY, calendar.get(Calendar.HOUR_OF_DAY));
            target.set(Calendar.MINUTE, calendar.get(Calendar.MINUTE));
            target.add(Calendar.DATE, 7);
        } else {
            if (calendar.get(Calendar.MINUTE) > now.get(Calendar.MINUTE)) {
                target.set(Calendar.HOUR_OF_DAY, calendar.get(Calendar.HOUR_OF_DAY));
                target.set(Calendar.MINUTE, calendar.get(Calendar.MINUTE));
            } else if (calendar.get(Calendar.MINUTE) < now.get(Calendar.MINUTE)) {
                target.set(Calendar.HOUR_OF_DAY, calendar.get(Calendar.HOUR_OF_DAY));
                target.set(Calendar.MINUTE, calendar.get(Calendar.MINUTE));
                target.add(Calendar.DATE, 7);
            } else {
                // target time is now!
            }
        }
    }

    long remainingTime = target.getTimeInMillis() - now.getTimeInMillis();
    final long hr = TimeUnit.MILLISECONDS.toHours(remainingTime);
    final long min = TimeUnit.MILLISECONDS.toMinutes(remainingTime - TimeUnit.HOURS.toMillis(hr));
    String result =  String.format("%02d:%02d", hr, min);

Answer 2

要将这样的字符串转换为实际的日期对象，可以使用如下代码：

String str = "Fri Mar 1, 2013 4:30 PM";          
SimpleDateFormat sdf1 = new SimpleDateFormat("EEE MMM dd, yyyy hh:mm a");
Date date = sdf1.parse(str);
System.out.println("Date Object:" + date);
SimpleDateFormat sdf2 = new SimpleDateFormat("yyyy-MM-dd HH:mm a");
System.out.println("Formatted Date:" + sdf2.format(date));

编辑：

因此，从编辑开始，如果我正确理解了您的要求，则希望获得两个日期之间的时差（可能相隔几天），并希望以小时为单位显示它们之间的时间。

为此，您可以使用如下代码：

//1 minute = 60 seconds
//1 hour = 60 x 60 = 3600
//1 day = 3600 x 24 = 86400
public void printDifference(Date startDate, Date endDate) { 
    //milliseconds
    long different = endDate.getTime() - startDate.getTime();

    System.out.println("startDate : " + startDate);
    System.out.println("endDate : "+ endDate);
    System.out.println("different : " + different);

    long secondsInMilli = 1000;
    long minutesInMilli = secondsInMilli * 60;
    long hoursInMilli = minutesInMilli * 60;
    long daysInMilli = hoursInMilli * 24;

    long elapsedDays = different / daysInMilli;
    different = different % daysInMilli;

    long elapsedHours = different / hoursInMilli;
    different = different % hoursInMilli;

    long elapsedMinutes = different / minutesInMilli;
    different = different % minutesInMilli;

    long elapsedSeconds = different / secondsInMilli;

    System.out.printf(
        "%d days, %d hours, %d minutes, %d seconds%n", 
        elapsedDays, elapsedHours, elapsedMinutes, elapsedSeconds);
}

Answer 3

与毫厘一起工作应该毫不费力。请记住，1000毫秒= 1秒。进行数学运算，然后使用SimpleDateFormat将结果转换为所需的格式。另外，在使用dates时，请确保您导入的是java.util.Date而不是sql.Date。

PS：如何从字符串中获取日期：

    String TimeStringToConvertToActualDate;   //  Let's assume this is the string holding your time and you want to convert it to a date
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");   // Here you should write the format you are actually using instead of this one
    Date myDate = null;
    try {
       myDate= sdf.parse(TimeStringToConvertToActualDate);
    } catch (ParseException e) {
       e.printStackTrace();
    }

Answer 4

您可以使用Calendar类并仅与millis一起使用。

以下代码更改了时间或一个月中的某几天：

Calendar c = Calendar.getInstance();
c.add(Calendar.HOUR_OF_DAY, 1);
c.add(Calendar. DAY_OF_MONTH, 1);

您可以根据需要使用getTime()方法获得Date对象。

获取时间直到我在android中指定的时间

4 个答案: