package exp3; //类-人 class Person{ //成员变量 String name; //姓名 int age; //年龄 //无参构造"人" public Person(){ this.name = "无名"; this.age = 18; } //有参构造"人" public Person(String name, int age){ this.name = name; this.age = age; } //设置姓名 void setName(String name){ this.name = name; } //设置年龄 void setAge(int age){ this.age = age; } //行为-吃饭 void eat(Person p){ System.out.println(p.name+"吃饭"); } //行为-睡觉 void sleep(Person p){ System.out.println(p.name+"睡觉"); } } //类-学生 继承自类-人 class Student extends Person{ //成员变量 String id; //无参构造 public Student(){ super(); this.id = "0000"; } //有参构造 public Student(String name, int age, String id){ super(name, age); this.id = id; } //设置id void setId(String id){ this.id = id; } //行为-学习 void study(Student s){ System.out.println(s.name+"学习"); } //方法-展示信息 void show(){ System.out.println("姓名: "+this.name); System.out.println("年龄: "+this.age); System.out.println("学号: "+this.id+"\n"); } } public class ExtendsDemo { public static void main(String[] args){ Student s1 = new Student(); Student s2 = new Student("梦之空", 20, "2230502119"); s1.show();; s2.show(); } }