Java 类的继承基础练习、GregorianCalendar的使用

仍然是课本上的练习题。题目如下: Y. Daniel Liang: Introduction to Java Programming 10th, p. 445 得到继承层次如图所示: 定义Person类 class Person { String name; String address; String phoneNumber; String emailAddress; public Person() { } public Person(String name, String address, String phoneNumber,