Java 中的 Calendar isSet()方法，带示例
原文:https://www . geesforgeks . org/calendar-isset-method-in-Java-with-examples/
calendar 类中的isSet(intcalndr _ field)方法用于检查给定的 Calendar 字段是否设置了值。通过内部字段的计算设置值的所有情况都由 get 方法调用触发。
语法:
public final boolean isSet(int calndr_field)
参数:该方法取一个参数 calndr_field ，指的是要操作的日历字段。 返回值:如果设置了日历字段的值，该方法返回真，否则返回假。
以下程序说明了日历类的 isSet()方法的工作原理:
例 1:
Java 语言(一种计算机语言，尤用于创建网站)
// 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);
}
}
Output:
The Year is: 2019
Is the Value set? true
Is the Value set? false
例 2:
Java 语言(一种计算机语言，尤用于创建网站)
// 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);
}
}
Output:
Todays Day is: 21
Is the Value set? true
Is the Value set? false
参考:T2【https://docs . Oracle . com/javase/8/docs/API/Java/util/calendar . html # isSet-int-T4】
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