Java Date before()用法及代码示例

Java Date类的before()方法测试日期是否在指定的日期之前。

用法:

public boolean before(Date when)

参数：该函数接受一个参数，该参数指定必须检查的日期。

返回值：它返回一个布尔值。如果此日期早于指定日期，它将返回true，否则返回false。

异常：如果when为null，该函数将引发单个异常，该异常为NullPointerException。

下面的程序演示了上述函数：

// Java code to demonstrate 
// before() 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(); 
  
        System.out.println("Date 1: " + dateOne); 
  
        // creating a date of object 
        // storing the current date 
        Date currentDate = new Date(); 
  
        System.out.println("Date 2: " + currentDate); 
  
        System.out.println("Is Date 2 before Date 1: "
                         + currentDate.before(dateOne)); 
    } 
}

输出：

Date 1: Thu Dec 05 08:15:01 UTC 1996
Date 2: Wed Jan 02 08:15:01 UTC 2019
Is Date 2 before Date 1: false

// Java code to demonstrate 
// before() 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(); 
  
        System.out.println("Date 1: " + currentDate); 
  
        // specifiedDate is assigned to null. 
        Date specifiedDate = null; 
  
        System.out.println("Date 1: " + specifiedDate); 
  
        System.out.println("On checking these 2 dates: "); 
  
        try { 
            // throws NullPointerException 
            System.out.println(currentDate 
                                   .before(specifiedDate)); 
        } 
        catch (Exception e) { 
            System.out.println("Exception: " + e); 
        } 
    } 
}

输出：

Date 1: Wed Jan 02 08:15:06 UTC 2019
Date 1: null
On checking these 2 dates: 
Exception: java.lang.NullPointerException

相关用法

注：本文由纯净天空筛选整理自Twinkl Bajaj大神的英文原创作品 Date before() method in Java with Examples。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。