date使用及び小練習

#日常練習
システム時間の取得方法、時間のフォーマット方法、個別の年月日の取得方法などを学びます.調査表法の転換の思想を身につける.

package Date;

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class DateDemo {

	public static void main(String[] args) {
		
		//      ， SimpleDateFormat（）    
		Date d = new Date();
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy MM dd E hh:mm:ss");
		String time = sdf.format(d);
		System.out.println(time);
		
		long l = System.currentTimeMillis();
		Date d1 = new Date(l);
		System.out.println("d1:"+d1);
		//    Calendar                 
		String month[] = {"  ","  ","  ","  ",
						  "  ","  ","  ","  ",
						  "  ","  ","   ","   "};
		String week[] = {"","   ","   ","   ","   ","   ","   ","   "};//  0  
		Calendar c = Calendar.getInstance();
		int monthIndex = c.get(Calendar.MONTH);
		int weekIndex = c.get(Calendar.DAY_OF_WEEK);
		System.out.println(c.get(Calendar.YEAR));
		//      0-11         ，
		//        ，          
		System.out.println(month[monthIndex]);
		System.out.println(c.get(Calendar.DAY_OF_MONTH));
		//                ，       
		System.out.println(week[weekIndex]);
	}

}

小練習:任意の年2月の日数を問い合わせる

package Date;
/*
 *   ：            。
 *   ：        Calendar.add（"yyyy,03,01",-1）。
 * */

import java.util.Calendar;

public class DayOfFebruary {

	public static void main(String[] args) {
		Calendar c = Calendar.getInstance();
		c.set(2000, 02, 01);//1997 03 01 
		c.add(Calendar.DAY_OF_MONTH,-1);
		System.out.println(c.get(Calendar.YEAR)+"    "+c.get(Calendar.DAY_OF_MONTH)+" ");

	}

}