第二个Java程序：本月日历的显示

显示本月的日历，每周的开始日期按照标准库中规定的日期，当天右侧用"*"进行标注，代码如下：

package Source1;

import java.text.DateFormatSymbols;
import java.util.*;
import java.io.*;
import java.awt.*;
import javax.swing.*;

public class Test2 {
    public static void main(String[] args){        
        GregorianCalendar now = new GregorianCalendar();
        int month = now.get(Calendar.MONTH);
        int today = now.get(Calendar.DAY_OF_MONTH);
        int intent = 0;
        now.set(Calendar.DAY_OF_MONTH,1);
        int week = now.get(Calendar.DAY_OF_WEEK);
        int firstDayOfWeek = now.getFirstDayOfWeek();
        while(firstDayOfWeek != week){
            ++intent;
            now.add(Calendar.DAY_OF_MONTH, -1);
            week = now.get(Calendar.DAY_OF_WEEK);
        }
        String[] weekdayNames = new DateFormatSymbols().getShortWeekdays();
        do{
            System.out.printf("%4s",weekdayNames[week]);
            now.add(Calendar.DAY_OF_MONTH, 1);
            week = now.get(Calendar.DAY_OF_WEEK);
        }while(week != firstDayOfWeek);
        System.out.println();
        for(int i = 0;i < intent;++i){
            System.out.print("    ");
        }
        now.set(Calendar.DAY_OF_MONTH, 1);
        week = now.get(Calendar.DAY_OF_WEEK);
        int day = now.get(Calendar.DAY_OF_MONTH);
        do{
            System.out.printf("%3s",day);
            if(today == day){
                System.out.print("*");
            }else{
                System.out.print(" ");
            }
            now.add(Calendar.DAY_OF_MONTH, 1);
            week = now.get(Calendar.DAY_OF_WEEK);
            day = now.get(Calendar.DAY_OF_MONTH);
            if(week == firstDayOfWeek){
                System.out.println();
            }
        }while(month == now.get(Calendar.MONTH));
        if(week != firstDayOfWeek){
            System.out.println();
        }
    }
}

运行后截图如下：