util包中Calendar对象的时间设置问题，请高手帮忙

package MonthTest;
import java.util.*;/**
*打印日历
*/
class MonthDemo{
Calendar today;
int month;
int year;
int weekday;
int day;
MonthDemo(){
today=Calendar.getInstance();
}
void shezhi(int y,int m){
today.clear();
today.set(Calendar.YEAR,y);
today.set(Calendar.MONTH,m);
today.set(Calendar.DAY_OF_MONTH, 1);
                today.getTime();
month=today.get(Calendar.MONTH)+1;
year=today.get(Calendar.YEAR);
weekday=today.get(Calendar.DAY_OF_WEEK);
}
void xianshi(){
System.out.println("\t\t\t  "+year+"年"+month+"月");
System.out.println("\t日\t一\t二\t三\t四\t五\t六");
for(int i=0;i<weekday;i++){
System.out.print("\t");
}
do{
System.out.print(today.get(Calendar.DATE)+"\t");
if(today.get(Calendar.DAY_OF_WEEK)==7)
System.out.print("\n\t");
today.add(Calendar.DAY_OF_MONTH,1);
}while(today.get(Calendar.MONTH)==(month-1));
}
}
public class MonthTest{
public static void main(String args[]){
int y,m;
MonthDemo Md=new MonthDemo();
y=Integer.parseInt(args[0]);
m=Integer.parseInt(args[1]);
Md.shezhi(y,m);
Md.xianshi();
}
}
我在MonthDemo类的shezhi方法中将年和月都设置成了2006年8月，为啥打印出来的日历还是9月的啊
请高手指点，不剩感激