this

改成
public void setDate(int month, int day, int year) {
this.month = monthString(Month);
this.day = day;
this.year = year;
}


可改
public boolean precedes(this4_7 date) {
return (year <>
(year == date.year && getMonth() <>
(year == date.year && month.equals(date.month)
&& day <>
}