一、 继承相关
18．实现如下类之间的继承关系，并编写Music类来测试这些类。
package com.hry.test;
public class Instrument {
//输出弹奏乐器
public void play()
{
System.out.println("弹奏乐器");
}
}package com.hry.test;
public class Wind extends Instrument {
//输出"弹奏wind"
public void play()
{
System.out.println("弹奏wind");
}
//输出"调用wind的play2"
public void play2()
{
System.out.println("调用wind的play2");
}
}package com.hry.test;
public class Brass extends Instrument {
//输出"弹奏brass"
public void play()
{
System.out.println("弹奏brass");
}
//输出"调用brass的play2"
public void play2()
{
System.out.println("调用brass的play2");
}
}package com.hry.test;
public class Music {
//调用对象i的play方法
//调用tune方法，以Wind类对象为参数
////调用tune方法，以Brass类对象为参数
public static void tune(Instrument i){
i.play();
}
public static void main(String[] args)
{
Instrument i= new Instrument();
i.play();
Wind w= new Wind();
w.play();
w.play2();
Brass b= new Brass();
b.play();
b.play2();
}
}19．创建如下三个类：（People类中的三个方法分别输出一些信息，ChinaPeople
和AmericanPeople类重写父类的三个方法）。
package com.hry.test;;
public class People {
protected double height;
protected double weight;
public double getHeight() {
return height;
}
public void setHeight(double height) {
this.height = height;
}
public double getWeight() {
return weight;
}
public void setWeight(double weight) {
this.weight = weight;
}
public void speakHello()
{
}
public void averageHeight()
{
}
public void averageWeight()
{
}
}package com.hry.test;
public class ChinaPeople extends People{
public void chinaGoufu()
{
System.out.println("少林、太极、咏春拳");
}
public void speakHello()
{
System.out.println("中文");
}
public void averageHeight()
{
System.out.println("中国人平均身高为175cm");
}
public void averageWeight()
{
System.out.println("中国人平均体重是65kg");
}
}package com.hry.test;
public class AmericnPeople extends People{
public void chinaGoufu()
{
System.out.println("直拳");
}
public void speakHello()
{
System.out.println("英文");
}
public void averageHeight()
{
System.out.println("美国人平均身高为180cm");
}
public void averageWeight()
{
System.out.println("美国人平均体重是70kg");
}
}package com.hry.test;
public class TestPeople {
public static void main(String[] args) {
ChinaPeople c =new ChinaPeople();
c.speakHello();
c.averageHeight();
c.averageWeight();
AmericnPeople a=new AmericnPeople();
a.speakHello();
a.averageHeight();
a.averageWeight();
}
}
21．编写一个Java应用程序，该程序包括3个类：Monkey类、People类和主类
E。要求：
(1) Monkey类中有个构造方法：Monkey (String s)，并且有个public void speak()
方法，在speak方法中输出“咿咿呀呀......”的信息。
(2)People类是Monkey类的子类，在People类中重写方法speak(),在speak方法
中输出“小样的，不错嘛！会说话了！”的信息。
(3)在People类中新增方法void think()，在think方法中输出“别说话！认真思考！”
的信息。
(4)在主类E的main方法中创建Monkey与People类的对象类测试这2个类的功
能。
package com.hry.test;
public class Monkey {
Monkey(String s) //构造
{}
public void speak()
{
System.out.println("咿咿呀呀......");
}
}package com.hry.test;
public class People1 extends Monkey{
People1(String s) {
super(s);
// TODO 自动生成的构造函数存根
}
public void speak()
{
System.out.println("小样的，不错嘛！会说话了！");
}
public void think()
{
System.out.println("别说话！认真思考！");
}
}package com.hry.test;
public class E1 {
public static void main(String[] args) {
// TODO 自动生成的方法存根
Monkey m = new Monkey("tom");
m.speak();
People1 p = new People1("Xiaoming");
p.speak();
p.think();
}
}