第九章第五题（使用GregorianCalendar类）（Use GregorianCalendar class）

• *9.5（使用GregorianCalendar类）Java API中有一个位于包java.util中的类GregorianCalendar，可以使用它获得某个日期的年、月、日。他的无参构造方法构建一个当前日期的实例，get（GregorianCalendar.YEAR）、get(GregorianCalendar.MONTH)和get(GregorianCalendar.DAY_OF_MONTH) 方法返回年、月和日。编写一个程序完成两个任务：

  • 显示当前的年、月和日。
  • GregorianCalendar类包含setTimeInMills（long）方法，可以用于设置从1970年1月1日算起的一个特定的流逝时间值。将这个值设置为1234567898765L，然后显示对应的年、月和日。

  *9.5（Use GregorianCalendar class）The Java API has a java.util You can use it to get the year, month, and day of a date. His nonparametric construction method builds an instance of the current date, get（ GregorianCalendar.YEAR ）、get( GregorianCalendar.MONTH ）And get（ GregorianCalendar.DAY_ OF_ The month) method returns the year, month, and day. Write a program to complete two tasks

  • Displays the current year, month, and day.
  • The gregoriancandar class contains the settimeinmills (long) method that can be used to set a specific elapsed time value from January 1, 1970. Set this value to 12345678988765l, and then display the corresponding year, month, and day.

• 参考代码：

package chapter09;

import java.util.GregorianCalendar;

public class Code_05 {
    public static void main(String[] args){
        GregorianCalendar calendar = new GregorianCalendar();
        System.out.println(calendar.get(calendar.YEAR) + ":" + calendar.get(calendar.MONTH) + ":" + calendar.get(calendar.DAY_OF_MONTH));

        calendar.setTimeInMillis(1234567898765L);
        System.out.println(calendar.get(calendar.YEAR) + ":" + calendar.get(calendar.MONTH) + ":" + calendar.get(calendar.DAY_OF_MONTH));
    }
}

• 结果显示：

2020:9:30
2009:1:14

Process finished with exit code 0