比较Java中的日期 [英] Comparing dates in Java

问题描述

我已经阅读日期函数，但我不能想出一个最好的方式来解决我的问题。

我有几个日期从数据库 String ，我想将它与当前日期进行比较。我使用 compareTo ，但是有一个问题使用这个函数我猜是因为我比较字符串。

这是我的函数：

  public int dateCompare（String today，String date2）{
 return today。 compareTo（date2）; 
} 
  

当我在示例日期中使用它时：

  dateCompare（04/19/2013​​，04/18/2013​​）; 
  

它返回1，当我将第一个参数的值更改为 04/20/2013仍会返回1。

请帮助...

Date 对象。你应该使用它。

  import java.util.Calendar; 
 import java.util.Date; 
 
 public class CompareDates {
 
 public static void main（String [] args）{
 //创建日历，默认为今天
 Calendar cal = Calendar.getInstance（）; 
 //减去1天
 cal.add（Calendar.DATE，-1）; 
 //比较结果（1）
 System.out.println（dateCompare（new Date（），cal.getTime（）））; 
 //添加2天
 cal.add（Calendar.DATE，2）; 
 //比较结果（-1）
 System.out.println（dateCompare（new Date（），cal.getTime（）））; 
} 
 
 public static int dateCompare（date today，Date date2）{
 System.out.println（Compare+ today +with+ date2）; 
 return today.compareTo（date2）; 
} 
} 
  

您也可以使用 Date API并在之前使用和在 ...

之后使用

 现在的日期= new Date（）; 
 
日历cal = Calendar.getInstance（）; 
 cal.add（Calendar.DATE，-1）; 
 System.out.println（now +isBefore+ cal.getTime（）+=+ now.before（cal.getTime（）））; 
 System.out.println（now +isAfter+ cal.getTime（）+=+ now.after（cal.getTime（）））; 
 cal.add（Calendar.DATE，2）; 
 System.out.println（now +isBefore+ cal.getTime（）+=+ now.before（cal.getTime（）））; 
 System.out.println（now +isAfter+ cal.getTime（）+=+ now.after（cal.getTime（）））; 
  

I already read date functions but i cant think a best way to solve my problem.

I have a couple of dates from database which is String and i want to compare it to may current date. I am using the compareTo, but there is a problem using this function i guess it is because of i was comparing strings.

This is my function:

public int dateCompare(String today, String date2){
    return today.compareTo(date2);
}

And when i use it in sample dates:

dateCompare("04/19/2013","04/18/2013");

it returns 1, and when i change the value of first parameter to "04/20/2013" it still returns 1.

Please HELP...

解决方案

Java has a Date object. You should be using that instead.

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

public class CompareDates {

    public static void main(String[] args) {
        // Create a calendar, this will default to today
        Calendar cal = Calendar.getInstance();
        // Subtract 1 day
        cal.add(Calendar.DATE, -1);
        // Compare the result (1)
        System.out.println(dateCompare(new Date(), cal.getTime()));
        // Add 2 days
        cal.add(Calendar.DATE, 2);
        // Compare the result (-1)
        System.out.println(dateCompare(new Date(), cal.getTime()));            
    }

    public static int dateCompare(Date today, Date date2) {
        System.out.println("Compare " + today + " with " + date2);
        return today.compareTo(date2);
    }
}

You could also just make use of the Date API and use before and after...

Date now = new Date();

Calendar cal = Calendar.getInstance();
cal.add(Calendar.DATE, -1);
System.out.println(now + " isBefore " + cal.getTime() + " = " + now.before(cal.getTime()));
System.out.println(now + " isAfter " + cal.getTime() + " = " + now.after(cal.getTime()));
cal.add(Calendar.DATE, 2);
System.out.println(now + " isBefore " + cal.getTime() + " = " + now.before(cal.getTime()));
System.out.println(now + " isAfter " + cal.getTime() + " = " + now.after(cal.getTime()));

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