Java如何使用date after()方法?

2021年3月20日17:10:54 发表评论 496 次浏览

java.util.Date.after()方法用于检查日期的当前实例是否在指定的日期之后。

语法如下:

dateObject.after(Date specifiedDate)

参数:仅需一个参数指定日期数据类型日期。与调用该函数的日期实例相比, 这是要检查的日期。

返回值:该函数的返回类型为boolean。它返回true如果日期的当前实例严格大于指定的日期。否则返回false.

例外情况:如果指定的日期为null, 则此方法将引发空指针异常当被要求时。

下面的程序说明Date类中的after()方法:

程序1:

// Java code to demonstrate
// after() function of Date class
  
import java.util.Date;
import java.util.Calendar;
public class GfG {
     // main method
     public static void main(String[] args)
     {
  
         // creating a Calendar object
         Calendar c = Calendar.getInstance();
  
         // set Month
         // MONTH starts with 0 i.e. ( 0 - Jan)
         c.set(Calendar.MONTH, 11 );
  
         // set Date
         c.set(Calendar.DATE, 05 );
  
         // set Year
         c.set(Calendar.YEAR, 1996 );
  
         // creating a date object with specified time.
         Date dateOne = c.getTime();
  
         // creating a date of object
         // storing the current date
         Date currentDate = new Date();
  
         System.out.print( "Is currentDate after date one : " );
  
         // if currentDate is after dateOne
         System.out.println(currentDate.after(dateOne));
     }
}

输出如下:

Is currentDate after date one : true

程式2:演示java.lang.NullPointerException

// Java code to demonstrate
// after() function of Date class
  
import java.util.Date;
  
public class GfG {
     // main method
     public static void main(String[] args)
     {
  
         // creating a date of object
         // storing the current date
         Date currentDate = new Date();
  
         // specifiedDate is assigned to null.
         Date specifiedDate = null ;
  
         System.out.println( "Passing null as parameter : " );
         try {
             // throws NullPointerException
             System.out.println(currentDate.after(specifiedDate));
         }
         catch (Exception e) {
             System.out.println( "Exception: " + e);
         }
     }
}

输出如下:

Passing null as parameter : 
Exception: java.lang.NullPointerException

木子山

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