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最新推荐文章于 2025-12-15 08:57:28 发布

原创最新推荐文章于 2025-12-15 08:57:28 发布 · 194 阅读

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#java #servlet #服务器

本文通过一系列Java代码示例，包括类的继承、抽象类与接口的应用，展示了Java中继承和多态的概念。示例涵盖了子类对父类方法的重写、抽象方法的实现、对象的转型以及接口的使用等核心概念。

Example5_1

package england.people;
import american.people.Son;
import japan.people.Grandson;
public class Example5_1 {
    public static void main(String args[]){
        Son son = new Son();
        Grandson grandson = new Grandson();
        son.height = 180;
        son.hand = "一双大手";
        grandson.height = 155;
        grandson.hand = "一双小手";
        grandson.food = "一双小脚";
        String str = son.getHand();
        System.out.println("儿子：%是，%d\n",str,son.height);
        str = grandson.getHand();
        System.out.println("孙子:%s,%s,%d\n",str,grandson.foot,grandson.height);
    }
}

Example5_3

class People{
    public double x;
    public void setX(double x){
        this.x=x;
    }
    public double getDoubleX(){
        return x;
    }
}
class Student extends people{
    int x;
    public int getX(){
        //x=20.56;
        return x;
    }
}
public class Example5_3 {
    public static void main(String args[]){
        Student stu = new Student();
        stu.x=98;
        System.out.println("对象stu的x的值是:"+stu.getX());
        stu.setX(98.98);
        double m = stu.getDoubieX();
        System.out.println("对象stu隐藏的x的值是："+m);
    }
}

Example5_4

class A{
    double f(float x,float y){
        return x+y;
    }
    public int g(int x,int y){
        return x+y;
    }
}
class B extends A{
    double f(float x,float y){
        return x*y;
    }
}public class Example5_4 {
    public static void main(String args[]){
        B b=new B();
        double result = b.f(5,6);
        System.out.println("调用重写方法得到的结果:"+result);
        int m =   (3,5);
        System.out.println("调用继承方法得到的结果："+result);
    }
}

Example5_6

public class Example5_6 {
    public static void main(String args[]){
        UniverStudent zhang = new UniverStudent(20111,"张三",false);
        int number = zhang.getNumber();
        String name = zhang.getName();
        boolean marriage = zhang.getIsMarriage();
        System.out.println(name+"的学号是："+number);
        if(marriage==true){
            System.out.println(name+"已婚");
        }
        else{
            System.out.println(name+"未婚");
        }
    }
}

Example5_7

public class Example5_7 {
    public static void main(String args[]){
        Average aver = new Average();
        aver.n = 100.5678;
        double result1 = aver.f();
        double result2 = aver.g();
        System.out.println("result1="+result1);
        System.out.println("result2="+result2);
    }
}

Example5_9

public class Example5_9 {
    public static void main(String args[]){
        People people = new People();
        Anthropoid monkey = people;
        monkey.crySpeak("I love this game");
        //monkey.n = 100;
        //monkey.computer(12,19);
        System.out.println(monkey.m);
        System.out.println(people.m);
        People zhang = (People)monkey;
        zhang.computer(55,33);
        zhang.m='T';
        System.out.println(zhang.m);
    }
}

Example5_11

bstract class GirlFriend{
    abstract void speak();
    abstract void cooking();
}
class ChinaGirlFriend extends GirlFriend{
    void speak(){
        System.out.println("你好");
    }
    void cooking(){
        System.out.println("水煮鱼");
    }
}
class AmericanGirlFriend extends GirlFriend{
    void speak(){
        System.out.println("hello");
    }
    void cooking(){
        System.out.println("roast beef");
    }
}
class Boy{
    GirlFriend friend;
    void setGirlfriend(GirlFriend f){
        friend = f;
    }
}
public class Example5_11 {
    public static void main(String args[]){
        GirlFriend girl = new ChinaGirlFriend();
        Boy boy = new Boy();
        boy.setGirlfriend(girl);
        boy.showGirlFriend();
        girl = new AmericanGirlFriend();
        boy.setGirlfriend(girl);
        boy.showGirlFriend();
    }
}

Example5_13

public class Example5_13 {
    public static void main(String args[]){
        Simulator simulator = new Simulator();
        simulator.playSound(new Dog());
        simulator.playSound(new Cat());
    }
}

Example5_14

public class Example5_14 {
    public static void main(String args[]) {
        AAA a = new AAA();
        System.out.println("接口中的常量" + AAA.MAX);
        System.out.println("调用on方法(重写的):");
        a.on();
        System.out.println("调用sum方法（重写的）：" + a.sum(12, 18));
        System.out.println("调用接口提供的default方法" + a.max(12, 78));
        Printable.f();
    }
}

习题5

public class A {
    public final void f() {
        char cStart = 'a', cEnd = 'z';
        for (char c=cStart;c<= cEnd;c++) {
            System.out.print("" + c);
        }
    }
}
class B extends A {
    public void g() {
        char eStart = 'a',cEnd ='w';
        for (char c = cStart; c <= cEnd; c++) {
            System.out.print("" + c);
        }
    }
}
public class B{
    public static void main ( String args[]){
        B b=new B ();
        b.f();
        b.g();
    }
}