Java Calendar isSet()用法及代码示例

Calendar类中的isSet(int calndr_field)方法用于检查给定日历字段是否设置了值。通过内部字段的计算为其设置值的所有Case均由get方法调用触发。

用法:

public final boolean isSet(int calndr_field)

参数：该方法采用一个参数calndr_field，该参数表示要操作的日历字段。

返回值：如果设置了日历字段的值，则该方法返回True，否则返回False。

以下示例程序旨在说明Calendar类的isSet()方法的用法：

示例1:

// Java code to illustrate 
// isSet() method 
  
import java.util.*; 
public class CalendarDemo { 
    public static void main(String args[]) 
    { 
  
        // Creating a calendar object 
        Calendar calndr = Calendar.getInstance(); 
  
        // Displaying the calendar object 
        System.out.println("The Year is: "
                           + calndr.get(Calendar.YEAR)); 
  
        // Querying for the value if set or not 
        boolean val = calndr.isSet(Calendar.YEAR); 
        System.out.println("Is the"
                           + " Value set? " + val); 
  
        // Clearing the instance 
        calndr.clear(Calendar.YEAR); 
  
        // Performing isSet() operation 
        val = calndr.isSet(Calendar.YEAR); 
        System.out.println("Is the"
                           + " Value set? " + val); 
    } 
}

输出：

The Year is: 2019
Is the Value set? true
Is the Value set? false

示例2:

// Java code to illustrate 
// isSet() method 
  
import java.util.*; 
public class CalendarDemo { 
    public static void main(String args[]) 
    { 
  
        // Creating a calendar object 
        Calendar calndr = Calendar.getInstance(); 
  
        // Displaying the calendar object 
        System.out.println("Todays Day is: "
                           + calndr.get( 
                                 Calendar.DAY_OF_MONTH)); 
  
        // Querying for the value if set or not 
        boolean val 
            = calndr.isSet(Calendar.DAY_OF_MONTH); 
        System.out.println("Is the"
                           + " Value set? " + val); 
  
        // Clearing the instance 
        calndr.clear(Calendar.DAY_OF_MONTH); 
  
        // Performing isSet() operation 
        val = calndr.isSet(Calendar.DAY_OF_MONTH); 
        System.out.println("Is the"
                           + " Value set? " + val); 
    } 
}

输出：

Todays Day is: 21
Is the Value set? true
Is the Value set? false

参考： https://docs.oracle.com/javase/8/docs/api/java/util/Calendar.html#isSet-int-

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注：本文由纯净天空筛选整理自Chinmoy Lenka大神的英文原创作品 Calendar isSet() 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。