class MyDate {
    int year;
    int month;
    int day;
    void setDate(int y,int m, int d){
	   if(d>31) System.out.println("day too big error");
           year = y; month = m; day = d;
    }
    void tomorrow(){
           if(day>31) System.out.println("day too big");
           day = day + 1;
    }
}
class Encap1 {
    public static void main(String[] args) {
        MyDate t = new MyDate();
        t.setDate(2003,3,32);  //此處錯誤可以被檢測出來
        t.day = t.day +1;  //此處錯誤不能被檢測出來
        
    }
}