问将生日添加到我的Employee类java

EN

// declare  birthday as Date:

private Date birthday;

public Employee(String name, int idNumber, String gender, 
    int year, int month, int day) {

    this.name  = name;
    this.idNumber = idNumber;
    this.gender = gender;
    initBirthday(year, month, day);
}

private void initBirthday(int year, int month, int day) {
    // all int should be greater than 0 
    if (year > 0 && month > 0 && day > 0) {
        Calendar cal = Calendar.getInstance();
        cal.set(year, month-1 , day, 0, 0, 0);
// OR the explicit way 
 //           cal.set(Calendar.YEAR, year);
 //           cal.set(Calendar.MONTH, month - 1); // january == 0 !!!!
 //           cal.set(Calendar.DAY_OF_MONTH, day);
 //           cal.set(Calendar.HOUR,0);
 //           cal.set(Calendar.MINUTE,0);
 //           cal.set(Calendar.SECOND,0);
            birthday = cal.getTime(); // this returns a Date
    } else {
       // set birthday to a default value...
    }
}