day_of_week.javaとleap_year.java（うるう年計算）を使いcalendar.javaのcmdを出したい。

sample53.java

import java.io.*;

public class sample53{
public static void main(String[] args) throws Exception{
BufferedReader in =
new BufferedReader(new InputStreamReader(System.in));

System.out.print("Year?: ");
String str1 = in.readLine();
System.out.print("Month?: ");
String str2 = in.readLine();

int year = Integer.parseInt(str1);
int month = Integer.parseInt(str2);
int dow = dayofweek(year, month);
int dim = daysinmonth(year, month);

showcal(dow, dim);
}

// カレンダーを表示する
public static void showcal(int dow, int days) throws Exception{
System.out.println("Su Mo Tu We Th Fr Sa");

int d = 1;
int i;

// 最初の週の表示 
for(i = 0; i < dow; i++){
    System.out.print("   ");
}
for(; i < 7; i++){
    System.out.print(" " + d + " ");
    d++;
}
System.out.println();

// 二週目以降の表示
for(int j = 0; d <= days; j++){
    for(i = 0; i < 7 && d <= days; i++){
	if(d < 10)
	    System.out.print(" " + d + " ");
	else
	    System.out.print(d + " ");
	d++;
    }
    System.out.println();
}
}

// 月の日数をかえす
public static int daysinmonth(int year, int month) throws Exception{
int dim = 31;
if(month == 4 || month == 6 || month == 9 || month == 11)
    dim = 30;
if(month == 2){
    if((year % 4 == 0 && year % 100 != 0) || year % 400 == 0)
	dim = 29; // うるう年
    else
	dim = 28;
}
return dim;
}

// 年の日数をかえす
public static int daysinyear(int year) throws Exception{
int diy;
if((year % 4 == 0 && year % 100 != 0) || year % 400 == 0)
    diy = 366; // うるう年
else
    diy = 365;
return diy;
}

// 月の初日の曜日をかえす
public static int dayofweek(int year, int month) throws Exception{
int days = 0;
int y = 0, m = 0;
int dow = 0;

// 2000年以降
if(year >= 2000){
    for(y = 2000; y < year; y++){
	days = days + daysinyear(y);
    }
    for(m = 1; m < month; m++){
	days = days + daysinmonth(year, m);
    }
    dow = (days + 6) % 7;
}

// 1999年以前
else{
    for(m = month; m <= 12; m++){
	days = days + daysinmonth(year, m);
    }
    for(y = year + 1; y < 2000; y++){
	days = days + daysinyear(y);
    }
    dow = 6 - days % 7;
}
return dow;
}

}

day_of_week.java

import java.util.Date;
import java.util.Calendar;

class day_of_week{

String yo(int b_yy, int b_mm , int b_dd){
Date today = new Date();
Calendar cal = Calendar.getInstance();
cal.set(Calendar.YEAR, b_yy);
cal.set(Calendar.MONTH, b_mm-1);
cal.set(Calendar.DATE,b_dd);

int h = cal.get(Calendar.DAY_OF_WEEK);
String yo ="";
switch(h){
	case 1: yo = "日"; break;
	case 2: yo = "月"; break;
	case 3: yo = "火"; break;
	case 4: yo = "水"; break;
	case 5: yo = "木"; break;
	case 6: yo = "金"; break;
	case 7: yo = "土"; break;
}


return yo;
}

}

leap_year.java
メソッド名は何でもおｋ(年){
うるう年計算
2月末日返す
(28または29)

cmd

Year?: 2015
Month?: 2
Su Mo Tu We Th Fr Sa
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

よろしくお願いいたします。