java - 如何检查Java中的日期是否大于另一个日期？

Question

我正在开发一个 Java 应用程序，它会在用户在命令行中输入的持续时间生成报告。用户需要按以下格式输入日期：dd-MM-yyyy

> java report startDate endDate

例子：

Java 报告 01-01-2013 31-03-2013

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。是否有一个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。

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();
    }
}

Answer 2

将字符串解析为日期，然后使用compareTo,before或之后进行比较

Date d = new Date();
d.compareTo(anotherDate)

IE

Date date1 = new SimpleDateFormat("MM/dd/yyyy").parse(date1string)
Date date2 = new SimpleDateFormat("MM/dd/yyyy").parse(date2string)

date1.compareTo(date2);

复制@MuhammadSaqib 下面提供的评论以完成此答案。

如果参数 Date 等于此 Date，则返回值 0；如果此 Date 在 Date 参数之前，则值小于 0，如果此 Date 在 Date 参数之后，则值大于 0。和 NullPointerException - 如果 anotherDate 为空。

比较的 javadoc http://docs.oracle.com/javase/6/docs/api/java/util/Date.html#compareTo(java.util.Date)

Answer 3

解析两个日期firstDate并secondDate使用SimpleDateFormat.

firstDate.after(secondDate);

firstDate.before(secondDate);

Answer 4

您需要使用SimpleDateFormat(dd-MM-yyyy将是格式) 将 2 个输入字符串解析为Date对象，然后使用Date#before(otherDate)(or)Date#after(otherDate)比较它们。

尝试自己实现代码。