如何检查日期是否大于Java中的日期？ [英] How to check if a date is greater than another in Java?

问题描述

我正在处理一个Java应用程序，该应用程序会在命令行中生成用户输入的持续时间的报告。用户需要输入以下格式的日期：dd-MM-yyyy

I am working on a Java application which generates a report for a duration entered by a user in the command line. The user needs to enter the dates in the following format: dd-MM-yyyy

> java报告startDate endDate

示例：

java报告01-01-2013 31-03-2013

java report 01-01-2013 31-03-2013

在代码中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是早于结束日期的日期。
是否有内置函数可以通过将这两个字符串传递给它来实现此目的？

In the code I save the dates in two strings. I have to make sure that the start date entered by the user should be a date earlier than the end-date. Is there an built-in function which can help me achieve this by passing these two strings to it?

推荐答案

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

You can use Date.before() or Date.after() or Date.equals() for date comparison.

取自这里：

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();
    }
}

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