1、编写一个Java应用程序，除了主类（Testone）外，该程序中还有3个 类：People、ChinaPeople和AmericanPeople。该程序具体要求如下： 1）People类有publicvoidspeakHe11o0、publicvoid averagelleight0和publicvoidaverageWeight0方法。 2）ChinaPeople类是People的子类，新增了publicvoidchinaGongfu( 方法。要求ChinaPeople重写父类的publicvoidspeaklle11o0、publicvoid averagelleight(和publicvoidaveragelleight(方法。 3）AmericanPeople类是People的子类，新增publicvoid americanBoxing0方法。要求AmericanPeople重写父类的publicvoid speakHello public void averageHleight0和publicvoid averageveight0方法。 4）在Testone类的主方法中分别创建各子类的对象并调用各自的方法打印 输出信息。 2

下面是Java应用程序的代码实现：

People.java

public class People {
    public void speakHello() {
        System.out.println("Hello!");
    }

    public void averageHeight() {
        System.out.println("The average height is 170cm.");
    }

    public void averageWeight() {
        System.out.println("The average weight is 60kg.");
    }
}

ChinaPeople.java

public class ChinaPeople extends People {
    public void chinaGongfu() {
        System.out.println("I can do China Gongfu!");
    }

    @Override
    public void speakHello() {
        System.out.println("你好！");
    }

    @Override
    public void averageHeight() {
        System.out.println("中国人的平均身高为 165cm。");
    }

    @Override
    public void averageWeight() {
        System.out.println("中国人的平均体重为 55kg。");
    }
}

AmericanPeople.java

public class AmericanPeople extends People {
    public void americanBoxing() {
        System.out.println("I can do American Boxing!");
    }

    @Override
    public void speakHello() {
        System.out.println("Hi!");
    }

    @Override
    public void averageHeight() {
        System.out.println("The average height of American people is 175cm.");
    }

    @Override
    public void averageWeight() {
        System.out.println("The average weight of American people is 75kg.");
    }
}

Testone.java

public class Testone {
    public static void main(String[] args) {
        People p1 = new People();
        p1.speakHello();
        p1.averageHeight();
        p1.averageWeight();

        ChinaPeople p2 = new ChinaPeople();
        p2.speakHello();
        p2.averageHeight();
        p2.averageWeight();
        p2.chinaGongfu();

        AmericanPeople p3 = new AmericanPeople();
        p3.speakHello();
        p3.averageHeight();
        p3.averageWeight();
        p3.americanBoxing();
    }
}

在Testone类的main方法中，我们分别创建了一个People对象p1，一个ChinaPeople对象p2和一个AmericanPeople对象p3，并分别调用它们的方法打印输出信息。其中，p2对象重写了父类People的三个方法，并新增了一个方法chinaGongfu()，而p3对象也重写了父类People的三个方法，并新增了一个方法americanBoxing()。