子类与继承

People：

package jichen;public class People {protected double weight, height;public void speakHello() {System.out.println("yayaya");}public void averageHeight() {height = 173;System.out.println("average height :" + height);}public void averageWeight() {weight = 70;System.out.println("average weight :" + weight);}}

ChinaPeople：

package jichen;public class ChinaPeople extends People {public void speakHello() {System.out.println("你好");}public void averageHeight() {height = 168;System.out.println("中国人的平均身高为：" + height);}public void averageWeight() {weight = 65;System.out.println("中国人的平均体重为：" + weight);}public void chinaGongfu() {System.out.println("坐如钟，站如松，睡如弓");}}

AmericanPeople：

package jichen;public class AmericanPeople extends People {public void speakHello() {System.out.println("How do you do ");}public void averageHeight() {height = 176;System.out.println("American's average height:" + height);}public void averageWeight() {weight = 75;System.out.println("American's average weight:" + weight);}public void americanBoxing() {System.out.println("直拳，勾拳，组合拳");}}

BeijingPeople：

package jichen;public class BeijingPeople extends ChinaPeople {public void averageHeight() {height = 172.5;System.out.println("北京人的平均身高为：" + height);}public void averageWeight() {weight = 70;System.out.println("北京人的平均体重为：" + weight);}public void beijingOpera() {System.out.println("花脸，青衣，花旦和老生");}}

Example：

package jichen;public class Example {   public static void main(String args[]){   ChinaPeople chinaPeople = new ChinaPeople();   AmericanPeople americanPeople = new AmericanPeople();   BeijingPeople beijingPeople = new BeijingPeople();   chinaPeople.speakHello();   americanPeople.speakHello();   beijingPeople.speakHello();   chinaPeople.averageHeight();   chinaPeople.averageWeight();   americanPeople.averageHeight();   americanPeople.averageWeight();   beijingPeople.averageHeight();   beijingPeople.averageWeight();   chinaPeople.chinaGongfu();   americanPeople.americanBoxing();   beijingPeople.beijingOpera();   beijingPeople.chinaGongfu();   }}

结果：