李雷與韓梅梅的對話（java類與繼承）

package cha4;

public class Person {
	
	String name;
	int age;
	Person(String n,int a){
		name = n;
		age = a;
	}
	Person(String n){
		name =n;
		age = 0;
	}
	Person(int age,String name){
		this.age=age;
		this.name=name;
	}
	Person(){
		this(0,"");
	}
	boolean isOlderThan(int anAge) {
		return this.age>anAge;
	}
	void sayHello() {
		System.out.println("Hello!My name is "+name);
	}
	void sayHello(Person another) {
		System.out.println("Hello,"+name+"!Myname is:"+another.name);
	}
	public static void main(String[] args) {
		Person p=new Person("Li Lei",18);
		Person p2=new Person("Han Mei Mei",20);
		p.sayHello();
		p.sayHello(p2);
	}
}

下面還是一個小李子，繼承了上面的Person類

package cha4;

public class Student extends Person {
	String school;
	int score;
	void sayHello(Student another) {
		System.out.println("Hi!");
		if(school==another.school) {
			System.out.println("Schoolmates");
		}
		
	}
	boolean isGoodStudent() {
		return score>=90;
	}
	void sayHello() {
		super.sayHello();
		System.out.println("My school is"+school);
	}
	Student(String name,int age,String school){
		super(name,age);
		this.school=school;
	}
	Student(){}
	void testThisAndSuper() {
		int a;
		a=age;
		a=this.age;
		a=super.age;
	}
	public static void main(String[]args) {
		Person p=new Person ("Li Lei",50);
		Student s=new Student("Han Mei Mei",20,"PKU");
		Person p2=new Student("Zhangyi",18,"THU");
		Student s2=(Student)p2;
		p.sayHello(s);
		Person[]manypeople=new Person[100];
		manypeople[0]=new Person("Li",18);
		manypeople[1]=new Student("Han",18,"PKU");
	}
}