类的继承

定义Person类，变量name，ID。 用户不能直接修改这些变量，但可以通过getName,setName方法获取Name 属性和设置Name属性，ID也是如此访问。// Person.java

 

Java代码：

package third_first_second;



    public class Person {

    private char name;

    private char ID;
   


    public char getName() {

    return this.name;

    }



    public char getID() {

    return this.ID;

    }



    public void setName(char name) {

    this.name = name;

    }



    public void setID(char ID) {

    this.ID = ID;

    }



    public void eat() {

    System.out.println("大多数人用筷子或刀叉吃饭");

    }

}

 

定义Person类的eat()方法。定义American类，和Chinese类，分别继承Person 类，并重写Person 类的eat方法。American的eat方法输出“我用刀叉吃西餐”。Chinese 的eat方法输出”我用筷子吃中餐”。并用测试类调用测试。 //American.java, Chinese.java

 

Java代码：

package third_first_second;



public class Chinese extends Person{

public void eat() {

System.out.println("我用筷子吃中餐");

}

}



package third_first_second;



public class American extends Person{

public void eat() {

System.out.println("我用刀叉吃西餐");

}

}



package third_first_second;



public class Demo_one {

public static void main(String args[]) {

Person person = null;

person = new Chinese();

person.eat();

person = new American();

person.eat();

}

}



package third_first_second;



public class Demo_two {

public static void main(String[] args) {

Chinese chinese = new Chinese();

American american = new American();

chinese.eat();

american.eat();

}

}

 

设计一个汽车类Auto,其有速度属性speed，以及启动start、加速speedup和停止stop方法，从Auto类派生一个子类Bus，以表示公共汽车，且Bus增加一个表示乘客数的属性passenger,另外添连个表示乘客上车和下车的方法getOn和getOff.  //Auto.java, Bus.java

 

java代码：

package third_third;



public abstract class Auto {

int speed;

int start;

int speedup;

abstract void stop();

}



package third_third;



public abstract class Bus extends Auto{

int passenger;

abstract void getOn();

abstract void getOff();

}

 

P88的实验2

Java代码：

package third_fourth_first;



public class School {

Teacher mathTeacher, musicTeacher;

void setTeacher(Teacher t1, Teacher t2) {

mathTeacher = t1;

musicTeacher = t2;

}



void startMathLesson() {

mathTeacher.speak();

}



void startMusicLesson() {

musicTeacher.speak();

}

}



package third_fourth_first;



public class Teacher {

int teacherType;

public void speak() {

if(teacherType == 1) {

System.out.println("课程的内容是二次方程");

}

else if(teacherType == 2) {

System.out.println("课程的内容是学唱五线谱");

}

}

}



package third_fourth_first;



public class MainClass {

public static void main(String[] args) {

Teacher zhang, wang;

zhang = new Teacher();

wang = new Teacher();

zhang.teacherType = 1;

wang.teacherType = 2;

School 实验中学 = new School();

实验中学.setTeacher(zhang, wang);

实验中学.startMathLesson();

实验中学.startMusicLesson();

}

}

 

p89实验三

Java代码：

package third_fourth_second;



public class Village {

static int treeAmout;

int peopleNumber;

String name;

Village(String s){

name = s;

}



void treePlanting(int n) {

treeAmout = treeAmout + n;

System.out.println(name + "植树" + n + "颗");

}



void fellTree(int n) {

if(treeAmout - n > 0) {

treeAmout = treeAmout - n;

System.out.println(name + "伐树" + n + "颗");

}

else {

System.out.println("无树木可伐");

}

}



static int lookTreeAmout() {

return treeAmout;

}



void addPeopleNumber(int n) {

peopleNumber = peopleNumber + n;

System.out.println(name + "增加了" + n + "人");

}

}



package third_fourth_second;



public class MainClass {

public static void main(String[] args) {

Village zhaoZhuang, maJiaHeZhi;

zhaoZhuang = new Village("赵庄");

maJiaHeZhi = new Village("马家河子");

zhaoZhuang.peopleNumber = 100;

maJiaHeZhi.peopleNumber = 150;



Village.treeAmout = 200;//通过类名调用类变量并给赋初值

int leftTree = Village.treeAmout;

System.out.println("森林中有 " + leftTree + " 颗树");



zhaoZhuang.treePlanting(50);

leftTree = maJiaHeZhi.lookTreeAmout();//用对象访问类变量

System.out.println("森林中有 " + leftTree + " 棵树");



maJiaHeZhi.fellTree(70);

leftTree = Village.treeAmout;//用类名访问类变量

System.out.println("森林中有 " + leftTree + " 棵树");



System.out.println("赵庄的人口:" + zhaoZhuang.peopleNumber);

zhaoZhuang.addPeopleNumber(12);

System.out.println("赵庄的人口:" + zhaoZhuang.peopleNumber);



System.out.println("马家河子的人口:" + maJiaHeZhi.peopleNumber);

maJiaHeZhi.addPeopleNumber(10);

System.out.println("马家河子的人口:" + maJiaHeZhi.peopleNumber);

}

}

 

p118实验1.

Java代码：

package third_fourth_third;



public class Animal {

protected String name;

public void showName() {

System.out.println(name);

}



public void cry() {

System.out.println("不同动物的叫声是有区别的");

}

}



package third_fourth_third;



public class Dog extends Animal{

Dog(String s){

name = s;

}



public void cry() {

System.out.println("汪汪汪");

}



public void swimming() {

System.out.println(name + "会游泳");

}

}



package third_fourth_third;



public class Cat extends Animal{

Cat(){

name = "猫";

}



Cat(String s){

name = s;

}



public void cry() {

System.out.println("喵喵喵");

}



public void climbUpTree() {

System.out.println(name + "会爬树");

}

}



package third_fourth_third;



public class MainClass {

public static void main(String[] args) {

Dog dog = new Dog("小黄狗");

Cat cat = new Cat("小花猫");

dog.showName();

dog.cry();

dog.swimming();



cat.showName();

cat.cry();

cat.climbUpTree();

}

}