Java 日历 computeFields()方法及示例

Calendar类中的 computeFields() 方法用于将当前的毫秒时间值时间转换为field[]中提到的日历字段值的操作。

注意：这允许将为日历对象设置的新时间与日历字段的值同步起来。

语法

protected abstract void computeFields()

参数： 该方法不接受任何参数。

返回值： 该方法不返回任何值。

下面的程序说明了日历类的computeFields()方法的工作原理：

例1 :

// Java Code to illustrate
// computeFields() Method
  
import java.util.*;
  
public class CalendarClassDemo
    extends GregorianCalendar {
    public static void main(String args[])
    {
        // Creating calendar object
        CalendarClassDemo calndr = new CalendarClassDemo();
  
        // Displaying the current date
        System.out.println("The Current "
                           + "date is: " + calndr.getTime());
  
        // Clearing the calendar
        calndr.clear();
  
        // Set a new year and call
        // computeFields()
        calndr.set(GregorianCalendar.YEAR, 2016);
        calndr.computeFields();
  
        // Displaying the current date
        System.out.println("The recent"
                           + " date is: " + calndr.getTime());
    }
}

输出:

The Current date is: Wed Feb 13 16:15:15 UTC 2019
The recent date is: Wed Feb 13 16:15:15 UTC 2019

例2 :

// Java Code to illustrate
// computeFields() Method
  
import java.util.*;
  
public class CalendarClassDemo
    extends GregorianCalendar {
    public static void main(String args[])
    {
        // Creating calendar object
        CalendarClassDemo calndr = new CalendarClassDemo();
  
        // Displaying the current date
        System.out.println("The Current "
                           + "date is: " + calndr.getTime());
  
        // Clearing the calendar
        calndr.clear();
  
        // Set a new year and call
        // computeFields()
        calndr.set(GregorianCalendar.YEAR, 2000);
        calndr.computeFields();
  
        // Displaying the current date
        System.out.println("The recent"
                           + " date is: " + calndr.getTime());
    }
}

输出:

The Current date is: Wed Feb 13 16:15:18 UTC 2019
The recent date is: Wed Feb 13 16:15:18 UTC 2019

**参考资料: **https://docs.oracle.com/javase/7/docs/api/java/util/Calendar.html#computeFields()