Java 中的 Date before()方法，示例
原文:https://www . geeksforgeeks . org/date-before-in-method-in-Java-with-examples/
Java Date 类的 before() 方法测试日期是否在指定日期之前。
语法:
public boolean before(Date when)
参数:当指定需要检查的日期时，该功能接受单个参数。
返回值:返回布尔值。如果该日期在指定日期之前，它将返回 true，否则返回 false。
异常:当为空时，如果为空，函数抛出一个异常，即空指针异常。
下面的程序演示了上述功能:
// 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));
}
}
Output:
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);
}
}
}
Output:
Date 1: Wed Jan 02 08:15:06 UTC 2019
Date 1: null
On checking these 2 dates:
Exception: java.lang.NullPointerException
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