Java Date before()用法及代碼示例

Java Date類的before()方法測試日期是否在指定的日期之前。

用法:

public boolean before(Date when)

參數：該函數接受一個參數，該參數指定必須檢查的日期。

返回值：它返回一個布爾值。如果此日期早於指定日期，它將返回true，否則返回false。

異常：如果when為null，該函數將引發單個異常，該異常為NullPointerException。

下麵的程序演示了上述函數：

// 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)); 
    } 
}

輸出：

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); 
        } 
    } 
}

輸出：

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

相關用法

注：本文由純淨天空篩選整理自Twinkl Bajaj大神的英文原創作品 Date before() method in Java with Examples。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。