Java Calendar roll(int calndr_field, int amt)用法及代码示例

Calendar类中的roll(int calndr_field，int amt)方法用于对传递的日历字段进行操作，方法是将传递的数量添加到特定的日历字段，而无需更改大的字段值。注意：必须添加正数，而必须减去负数。

用法:

public void roll(int calndr_field, int amt)

参数：该方法有两个参数：

calndr_field:这是“日历”类型，是指要操作的日历字段。
amt:这是整数类型，将根据值的符号相加或相减。

返回值：该方法不返回任何值。

以下示例程序旨在说明Calendar类的roll()方法的用法：
范例1：

// Java code to illustrate 
// isSet() method 
  
import java.util.*; 
public class Calendar_Demo { 
    public static void main(String args[]) 
    { 
  
        // Creating a calendar 
        Calendar calndr = Calendar.getInstance(); 
  
        // Displaying the year 
        System.out.println("The Current Year"
                           + " is:"
                           + calndr.get( 
                                 Calendar.YEAR)); 
  
        // Decrementing the year 
        // by 5 
        calndr.roll(Calendar.YEAR, -5); 
  
        // Displaying the result after the operation 
        System.out.println("The New Year is:"
                           + calndr.get( 
                                 Calendar.YEAR)); 
  
        // Incrementing the year 
        // by 2 
        calndr.roll(Calendar.YEAR, 2); 
  
        // Displaying the result after operation 
        System.out.println("The new year is:"
                           + calndr.get( 
                                 Calendar.YEAR)); 
    } 
}

输出：

The Current Year is:2019
The New Year is:2014
The new year is:2016

范例2：

// Java code to illustrate 
// isSet() method 
  
import java.util.*; 
public class Calendar_Demo { 
    public static void main(String args[]) 
    { 
  
        // Creating a calendar 
        Calendar calndr = Calendar.getInstance(); 
  
        // Displaying the month 
        System.out.println("The Current Month"
                           + " is:"
                           + calndr.get( 
                                 Calendar.MONTH)); 
  
        // Incrementing the month 
        // by 3 
        calndr.roll(Calendar.MONTH, 3); 
  
        // Displaying the result after operation 
        System.out.println("The New Month is:"
                           + calndr.get( 
                                 Calendar.MONTH)); 
  
        // Decrementing the month 
        // by 1 
        calndr.roll(Calendar.MONTH, -1); 
  
        // Displaying the result after operation 
        System.out.println("The new month is:"
                           + calndr.get( 
                                 Calendar.MONTH)); 
    } 
}

输出：

The Current Month is:2
The New Month is:5
The new month is:4

参考： https://docs.oracle.com/javase/7/docs/api/java/util/Calendar.html#roll(int, %20int)

相关用法

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 roll(int calndr_field, int amt) 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。