Java 日历 computeTime()方法及示例

Calendar类中的 computeTime() 方法用于将字段[]中的当前日历字段值转换为毫秒级时间值的操作。

语法

protected abstract void computeTime()

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computeTime()方法的工作原理：

例1 :

// Java Code to illustrate
// computeTime() 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
        // computeTime()
        calndr.set(GregorianCalendar.YEAR, 2016);
        calndr.computeTime();
  
        // Displaying the current date
        System.out.println("The recent"
                           + " date is: " + calndr.getTime());
    }
}

输出:

The Current date is: Wed Feb 13 16:27:12 UTC 2019
The recent date is: Fri Jan 01 00:00:00 UTC 2016

例2 :

// Java Code to illustrate
// computeTime() 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
        // computeTime()
        calndr.set(GregorianCalendar.YEAR, 2000);
        calndr.computeTime();
  
        // Displaying the current date
        System.out.println("The recent"
                           + " date is: " + calndr.getTime());
    }
}

输出:

The Current date is: Wed Feb 13 16:27:15 UTC 2019
The recent date is: Sat Jan 01 00:00:00 UTC 2000

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