程序5-2
public class Date {
private int day,month,year;
Date ( int i,int j,int k) {
day = i;
month = j;
year = k;
}
Date() { //构造方法
day = 1;
month = 1;
year = 1998;
}
Date ( Date d) { 带一个参数的构造方法
day = d.day;
month = d.month;
year = d.year;
}
public void printDate() {
System.out.print(day + "/" + month + "/" + year);
}
public Date tomorrow() {
Date d = new Date(this);
d.day++;
if (d.day > d.daysInMonth()) {
d.day = 1;
d.month ++;
if (d.month > 12) {
d.month = 1;
d.year ++;
}
}
return d;
}
public int daysInMonth() {
switch (month) {
case 1,case 3,case 5,case 7,
case 8,case 10,case 12:
return 31;
case 4,case 6,case 9,case 11:
return 30;
default:
if ( year % 100 != 0 && year % 4 == 0 ) {
return 29;
}
else return 28;
}
}

public static void main (String args[]) {
Date d1 = new Date();
System.out.print("The current date is (dd / mm / yy),");
d1.printDate();
System.out.println();
System.out.print("Its tomorrow is (dd / mm / yy),");
d1.tomorrow().printDate();
System.out.println();
Date d2 = new Date(28,2,1964);
System.out.print("The current date is (dd / mm / yy),");
d2.printDate();
System.out.println();
System.out.print("Its tomorrow is (dd / mm / yy),");
d2.tomorrow().printDate();
System.out.println();
}
}