如何显示当前系统日期是这一年中的第几周和第几日？

Question

// get the supported ids for GMT-08:00 (Pacific Standard Time)
 String[] ids = TimeZone.getAvailableIDs(-8 * 60 * 60 * 1000);
 // if no ids were returned, something is wrong. get out.
 if (ids.length == 0)
     System.exit(0);  // begin output
 System.out.println("Current Time"); // create a Pacific Standard Time time zone
 SimpleTimeZone pdt = new SimpleTimeZone(-8 * 60 * 60 * 1000, ids[0]); // set up rules for daylight savings time
 pdt.setStartRule(Calendar.APRIL, 1, Calendar.SUNDAY, 2 * 60 * 60 * 1000);
 pdt.setEndRule(Calendar.OCTOBER, -1, Calendar.SUNDAY, 2 * 60 * 60 * 1000); // create a GregorianCalendar with the Pacific Daylight time zone
 // and the current date and time
 Calendar calendar = new GregorianCalendar(pdt);
 Date trialTime = new Date();
 calendar.setTime(trialTime); // print out a bunch of interesting things
 System.out.println("ERA: " + calendar.get(Calendar.ERA));
 System.out.println("YEAR: " + calendar.get(Calendar.YEAR));
 System.out.println("MONTH: " + calendar.get(Calendar.MONTH));
 System.out.println("WEEK_OF_YEAR: " + calendar.get(Calendar.WEEK_OF_YEAR));
 System.out.println("WEEK_OF_MONTH: " + calendar.get(Calendar.WEEK_OF_MONTH));
 System.out.println("DATE: " + calendar.get(Calendar.DATE));
 System.out.println("DAY_OF_MONTH: " + calendar.get(Calendar.DAY_OF_MONTH));
 System.out.println("DAY_OF_YEAR: " + calendar.get(Calendar.DAY_OF_YEAR));
 System.out.println("DAY_OF_WEEK: " + calendar.get(Calendar.DAY_OF_WEEK));
 System.out.println("DAY_OF_WEEK_IN_MONTH: "
                    + calendar.get(Calendar.DAY_OF_WEEK_IN_MONTH));
 System.out.println("AM_PM: " + calendar.get(Calendar.AM_PM));
 System.out.println("HOUR: " + calendar.get(Calendar.HOUR));
 System.out.println("HOUR_OF_DAY: " + calendar.get(Calendar.HOUR_OF_DAY));
 System.out.println("MINUTE: " + calendar.get(Calendar.MINUTE));
 System.out.println("SECOND: " + calendar.get(Calendar.SECOND));
 System.out.println("MILLISECOND: " + calendar.get(Calendar.MILLISECOND));
 System.out.println("ZONE_OFFSET: "
                    + (calendar.get(Calendar.ZONE_OFFSET)/(60*60*1000)));
 System.out.println("DST_OFFSET: "
                    + (calendar.get(Calendar.DST_OFFSET)/(60*60*1000)));

Answer 1

谢谢你了 superszhu(精彩世界)，那如果我输入一个固定的日期也可以这样来算吗？

Answer 2

import java.util.Calendar;
import java.util.GregorianCalendar;public class test {    static public void main(String[] args) throws Exception {
        Calendar calendar = new GregorianCalendar(2004,6,22,16,10,10);
        
        System.out.println("ERA: " + calendar.get(Calendar.ERA));
         System.out.println("YEAR: " + calendar.get(Calendar.YEAR));
         System.out.println("MONTH: " + calendar.get(Calendar.MONTH));
         System.out.println("WEEK_OF_YEAR: " + calendar.get(Calendar.WEEK_OF_YEAR));
         System.out.println("WEEK_OF_MONTH: " + calendar.get(Calendar.WEEK_OF_MONTH));
         System.out.println("DATE: " + calendar.get(Calendar.DATE));
         System.out.println("DAY_OF_MONTH: " + calendar.get(Calendar.DAY_OF_MONTH));
         System.out.println("DAY_OF_YEAR: " + calendar.get(Calendar.DAY_OF_YEAR));
         System.out.println("DAY_OF_WEEK: " + calendar.get(Calendar.DAY_OF_WEEK));
         System.out.println("DAY_OF_WEEK_IN_MONTH: "
                            + calendar.get(Calendar.DAY_OF_WEEK_IN_MONTH));
         System.out.println("AM_PM: " + calendar.get(Calendar.AM_PM));
         System.out.println("HOUR: " + calendar.get(Calendar.HOUR));
         System.out.println("HOUR_OF_DAY: " + calendar.get(Calendar.HOUR_OF_DAY));
         System.out.println("MINUTE: " + calendar.get(Calendar.MINUTE));
         System.out.println("SECOND: " + calendar.get(Calendar.SECOND));
         System.out.println("MILLISECOND: " + calendar.get(Calendar.MILLISECOND));
         System.out.println("ZONE_OFFSET: "
                            + (calendar.get(Calendar.ZONE_OFFSET)/(60*60*1000)));
         System.out.println("DST_OFFSET: "
                    + (calendar.get(Calendar.DST_OFFSET)/(60*60*1000)));
        
    }}