JAVA核心技术 上的关于日历的一个程序 自己试了一下 发现有问题 求教了~~

Question

程序是这样的：
import java.util.*;
public class CalendarTest 
{
public static void main(String[] args)
{
GregorianCalendar d = new GregorianCalendar();
int today = d.get(Calendar.DAY_OF_MONTH);
int month = d.get(Calendar.MONTH);
d.set(Calendar.DAY_OF_MONTH,1);
int weekday = d.get(Calendar.DAY_OF_WEEK);
System.out.println("Sun Mon Tue Wed Thu Fri Sat");
for(int i = Calendar.SUNDAY;i < weekday;i++)
System.out.print("");

do
{
int day = d.get(Calendar.DAY_OF_MONTH);
System.out.printf("%3d", day);
if (day == today)
System.out.print("*");
else
System.out.println(" ");
if(weekday == Calendar.SATURDAY)
System.out.println();
d.add(Calendar.DAY_OF_MONTH,1);
weekday = d.get(Calendar.DAY_OF_WEEK);
}
while(d.get(Calendar.MONTH)== month);
if(weekday != Calendar.SUNDAY)
System.out.println();
}
}我在Eclipse上试了下 发现结果是这样的：
Sun Mon Tue Wed Thu Fri Sat
  1 
  2 
  3 
  4 
  5 
  6   7 
  8 
  9 
 10 
 11 
 12 
 13  14 
 15 
 16 
 17 
 18 
 19 
 20  21 
 22* 23 
 24 
 25 
 26 
 27  28 
 29 
 30 但是书上的结果，意思是应该就像通常的日历一样，按照星期下面排的日期 为什么这个结果是乱的，我应该没打错程序，都检查好几遍了，现在对JAVA还是一知半解，所以看了几遍程序还有点不明白，希望大家给看看程序，谢谢

Answer 1

if (day == today)
System.out.print("*");
else
System.out.println(" ");==>>if (day == today)
System.out.print("*");
else
System.out.print(" ");

Answer 2

import java.util.*;
public class CalendarTest {    public static void main(String[] args)
    {    
    GregorianCalendar d= new GregorianCalendar();
    int today=d.get(Calendar.DAY_OF_MONTH);
    int month=d.get(Calendar.MONTH);
    d.set(Calendar.DAY_OF_MONTH, 1);
    
    int weekday=d.get(Calendar.DAY_OF_WEEK);
    
    System.out.println("SUN MON TUE WED THU FRI SAT");
    
    for(int i=Calendar.SUNDAY;i<weekday;i++)
    
        System.out.print("    ");
    
    do
    {
    int day =d.get(Calendar.DAY_OF_MONTH);
    if(day<10)
    System.out.print(" ");
    
    
    System.out.print(day);
    
    if(day==today)
        System.out.print("* ");
    else
        System.out.print("  ");
    if(weekday==Calendar.SATURDAY)
    System.out.println();
    
    
    
    d.add(Calendar.DAY_OF_MONTH,1);
    
    weekday=d.get(Calendar.DAY_OF_WEEK);
    
    }
    while(d.get(Calendar.MONTH)==month);
    if(weekday!=Calendar.SUNDAY)
        System.out.println();
    }
}这个例子写的不对，试试这个

Answer 3

import java.util.*;public class CalendarTest {
public static void main(String[] args) {
GregorianCalendar d = new GregorianCalendar();
int today = d.get(Calendar.DAY_OF_MONTH);
int month = d.get(Calendar.MONTH);
d.set(Calendar.DAY_OF_MONTH, 1);
int weekday = d.get(Calendar.DAY_OF_WEEK);
System.out.println("Sun Mon Tue Wed Thu Fri Sat"); int day = d.get(Calendar.DAY_OF_MONTH);
switch (weekday) {
case Calendar.MONDAY:
System.out.printf("%7d", day);
break;
case Calendar.TUESDAY:
System.out.printf("%11d", day);
break;
case Calendar.WEDNESDAY:
System.out.printf("%15d", day);
break;
case Calendar.THURSDAY:
System.out.printf("%19d", day);
break;
case Calendar.FRIDAY:
System.out.printf("%23d", day);
break;
case Calendar.SATURDAY:
System.out.printf("%27d", day);
break;
case Calendar.SUNDAY:
System.out.printf("%31d", day);
break;
}
if (day == today)
System.out.print("*");
else
System.out.print(" ");
d.add(Calendar.DAY_OF_MONTH, 1);
weekday = d.get(Calendar.DAY_OF_WEEK); while (d.get(Calendar.MONTH) == month) {
day = d.get(Calendar.DAY_OF_MONTH);
System.out.printf("%3d", day);
if (day == today)
System.out.print("*");
else
System.out.print(" ");
if (weekday == Calendar.SATURDAY)
System.out.println();
d.add(Calendar.DAY_OF_MONTH, 1);
weekday = d.get(Calendar.DAY_OF_WEEK);
}
}
}月份第一个日期要判断是一周中的第几天 

Answer 4

// System.out.print("    ");    四个空格是什么意思？是不是有点固定了？