如何在Java中检查日期是否大于另一个日期？[重复]

Question

我正在使用Java应用程序，该应用程序会在用户在命令行中输入的持续时间内生成报告。用户需要以以下格式输入日期：dd-MM-yyyy

> java report startDate endDate

例：

java报告2013年1月1日至2013年3月31日

在代码中，我将日期保存在两个字符串中。我必须确保用户输入的开始日期应该早于结束日期。是否有内置函数可以通过将这两个字符串传递给它来帮助我实现这一目标？

Answer 1

您可以使用Date.before（）或Date.after（）或Date.equals（）进行日期比较。

从这里拍摄：

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class DateDiff {

    public static void main( String[] args )
    {
        compareDates("2017-01-13 00:00:00", "2017-01-14 00:00:00");// output will be Date1 is before Date2
        compareDates("2017-01-13 00:00:00", "2017-01-12 00:00:00");//output will be Date1 is after Date2
        compareDates("2017-01-13 00:00:00", "2017-01-13 10:20:30");//output will be Date1 is before Date2 because date2 is ahead of date 1 by 10:20:30 hours
        compareDates("2017-01-13 00:00:00", "2017-01-13 00:00:00");//output will be Date1 is equal Date2 because both date and time are equal
    }

    public static void compareDates(String d1,String d2)
    {
        try{
            // If you already have date objects then skip 1

            //1
            // Create 2 dates starts
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
            Date date1 = sdf.parse(d1);
            Date date2 = sdf.parse(d2);

            System.out.println("Date1"+sdf.format(date1));
            System.out.println("Date2"+sdf.format(date2));System.out.println();

            // Create 2 dates ends
            //1

            // Date object is having 3 methods namely after,before and equals for comparing
            // after() will return true if and only if date1 is after date 2
            if(date1.after(date2)){
                System.out.println("Date1 is after Date2");
            }
            // before() will return true if and only if date1 is before date2
            if(date1.before(date2)){
                System.out.println("Date1 is before Date2");
            }

            //equals() returns true if both the dates are equal
            if(date1.equals(date2)){
                System.out.println("Date1 is equal Date2");
            }

            System.out.println();
        }
        catch(ParseException ex){
            ex.printStackTrace();
        }
    }

    public static void compareDates(Date date1,Date date2)
    {
        // if you already have date objects then skip 1
        //1

        //1

        //date object is having 3 methods namely after,before and equals for comparing
        //after() will return true if and only if date1 is after date 2
        if(date1.after(date2)){
            System.out.println("Date1 is after Date2");
        }

        //before() will return true if and only if date1 is before date2
        if(date1.before(date2)){
            System.out.println("Date1 is before Date2");
        }

        //equals() returns true if both the dates are equal
        if(date1.equals(date2)){
            System.out.println("Date1 is equal Date2");
        }

        System.out.println();
    }
}