簡單練習Calendar, 還有當前月份的日曆顯示

testCalendar

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



public class Test {

    public static void main(String[] args) {

        Calendar rightNow = Calendar.getInstance();

        System.out.println("Calendar.MONTH : " + rightNow.get(Calendar.MONTH));

        int month = rightNow.get(Calendar.MONTH)+1;
        System.out.println("當前月份 : " + month);

        System.out.println("Calendar.DAY_OF_MONTH : " + rightNow.get(Calendar.DAY_OF_MONTH));
        System.out.println("Calendar.YEAR : " + rightNow.get(Calendar.YEAR));
        System.out.println("當前時間 : " + rightNow.get(Calendar.HOUR_OF_DAY) + ":" + rightNow.get(Calendar.MINUTE) + ":" + rightNow.get(Calendar.SECOND));
        System.out.println("Calendar.DAY_OF_WEEK : " + rightNow.get(Calendar.DAY_OF_WEEK));

        int week = rightNow.get(Calendar.DAY_OF_WEEK)-1;
        System.out.println("今天週幾 : " + week);

        //計算天數差距
        SimpleDateFormat simpleDay = new SimpleDateFormat("yyyyMMdd");

        Calendar c1 = Calendar.getInstance();
        c1.set(2014 , 4-1 , 5); //2014/4/5
        Date d1 = c1.getTime();
        System.out.println("日期1 : " + simpleDay.format(d1));

        Calendar c2 = Calendar.getInstance();
        c2.set(2014 , 11-1 , 2); //2014/11/2
        Date d2 = c2.getTime();
        System.out.println("日期2 : " + simpleDay.format(d2));

        long dateDiff = (d2.getTime() - d1.getTime())/(24*60*60*1000);

        System.out.println("2014-4-5 ~ 2014-11-2 差幾天 : " + dateDiff);


        //顯示當前月份的日曆
        Calendar dateNow = Calendar.getInstance();
        //當月天數
        int monthDayNum = dateNow.getActualMaximum(Calendar.DATE);

        //當月第一天是週幾
        dateNow.set(Calendar.DATE , 1); //設定dateNow為當天月份的第一天
        int firstDay = dateNow.get(Calendar.DAY_OF_WEEK)-1;

        String [] titleWeek = {"日" , "一" , "二" , "三" , "四" , "五" , "六"};
        for (int i = 0; i < titleWeek.length; i++) {
            System.out.print(titleWeek[i] + "  ");
        }
        System.out.println();

        //第1天在週幾的情況, 前面對應的空格數
        for (int i = 0; i < firstDay; i++) {
            System.out.print("    ");
        }

        for (int i = 1; i <= monthDayNum; i++) {

            System.out.print(i);
            if (i <10) {
                System.out.print("   ");
            }else {
                System.out.print("  ");
            }

            if ((firstDay+i)%7 ==0){
                System.out.println();
            }

        }


    }


}