java - 在 Java 中，我们如何将时间四舍五入到最接近的小时和分钟？

Question

我有一个有时间的字符串。我需要将它四舍五入到最近的小时和最近的分钟。我如何在 Java 中做到这一点？ 例如:String time="12:58:15"; 我需要将其四舍五入为 1:00:00 和 12:58:00

Answer 1

对于日历操作，您必须使用 Calendar 类。在你的情况下你会做这样的事情:

package test;

import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;

public class TestDate {

    public static void main(String[] args) {
        Calendar c = new GregorianCalendar();
        c.set(Calendar.HOUR_OF_DAY, 12);
        c.set(Calendar.MINUTE, 58);
        c.set(Calendar.SECOND, 15);
        Date d = c.getTime();

        System.out.println("Start point: " + d.toString());
        System.out.println("Nearest whole minute: " + toNearestWholeMinute(d));
        System.out.println("Nearest whole hour: " + toNearestWholeHour(d));
    }

    static Date toNearestWholeMinute(Date d) {
        Calendar c = new GregorianCalendar();
        c.setTime(d);

        if (c.get(Calendar.SECOND) >= 30)
            c.add(Calendar.MINUTE, 1);

        c.set(Calendar.SECOND, 0);

        return c.getTime();
    }

    static Date toNearestWholeHour(Date d) {
        Calendar c = new GregorianCalendar();
        c.setTime(d);

        if (c.get(Calendar.MINUTE) >= 30)
            c.add(Calendar.HOUR, 1);

        c.set(Calendar.MINUTE, 0);
        c.set(Calendar.SECOND, 0);

        return c.getTime();
    }

}

结果:

Start point: Tue Nov 22 12:58:15 CET 2011
Nearest whole minute: Tue Nov 22 12:58:00 CET 2011
Nearest whole hour: Tue Nov 22 13:00:00 CET 2011