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java实验三正式报告

时间：2024-07-06 08:20:53

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java实验三正式报告

实验三面向对象（二）（实验报告）

姓名：XXX班级：XXX学号：XXX

一、实验目的

在集成开发环境下，实现类的继承及多态，实现抽象类、接口的定义，根据实际问题，运用抽象方法、接口及抽象类进行程序开发。

二、实验目标

1. 能够运用Java语言来实现类的继承及多态性、熟练使用包来扩展程序功能并能建立自己的包；

2. 能够灵活运用Java语言的抽象方法、接口、抽象类来编写应用程序解决实际问题。

三、实验内容

3.1 实验环境

IntelliJ IDEA Ultimate Edition .3 x64. + openjdk-17.0.1.

3.2 具体实验内容

问题一

设计一个抽象类图形类，在该类中包含有至少三个抽象方法，分别用于求周长、求面积，以及对图形进行描述（如，“这是形状，周长是，面积是**”），分别定义圆形类、长方形类、等边三角形类来继承图形类，实现上述三个方法，并创建实例验证。

问题分析：定义抽象类用abstract关键字, 其他普通类继承该类即可，注意，抽象类被继承后，需要实现抽象类中的抽象方法

public class QuestionOne {public static void main(String[] args) {Shape shape1 = new Round(5);Shape shape2 = new Rectangle(2, 6);Shape shape3 = new EquilateralTriangle(3);shape1.describe();shape2.describe();shape3.describe();}}abstract class Shape {public abstract double calculatePerimeter ();public abstract void describe ();public abstract double calculateSquare ();}class Round extends Shape {private final double R;public Round(double r) {R = r;}@Overridepublic double calculatePerimeter() {return Math.PI * this.R * 2;}@Overridepublic void describe() {System.out.println("这是一个半径为" + this.R + "的圆, 面积为" + calculateSquare() + ", 周长为" + calculatePerimeter());}@Overridepublic double calculateSquare() {return Math.PI * this.R * this.R;}}class Rectangle extends Shape {private final double a;private final double b;public Rectangle(double a, double b) {this.a = a;this.b = b;}@Overridepublic double calculatePerimeter() {return this.a * 2 + this.b * 2;}@Overridepublic void describe() {System.out.println("这是一个长为" + this.a + ",宽为" + this.b + "的矩形, 面积为" + calculateSquare() + ", 周长为" + calculatePerimeter());}@Overridepublic double calculateSquare() {return this.a * this.b;}}class EquilateralTriangle extends Shape {private final double a;public EquilateralTriangle(double a) {this.a = a;}@Overridepublic double calculatePerimeter() {return this.a * 3;}@Overridepublic void describe() {System.out.println("这是一个变长为" + this.a + "的等边三角形, 面积为" + calculateSquare() + ", 周长为" + calculatePerimeter());}@Overridepublic double calculateSquare() {return this.a * this.a * 2 * Math.sqrt(3);}}

实验结果

这是一个半径为5.0的圆, 面积为78.53981633974483, 周长为31.41592653589793
这是一个长为2.0,宽为6.0的矩形, 面积为12.0, 周长为16.0
这是一个变长为3.0的等边三角形, 面积为31.17691453623979, 周长为9.0

问题二

定义一个抽象接口Lecture，接口中至少有两个抽象方法talk()与homework(),分别定义Student类与Teacher类实现Lecture接口，Student类的talk()方法用于模拟学生回答问题，Teacher类的talk()方法用于模拟老师提出问题，Student类的homework ()方法用于模拟学生写作业，Teacher类的homework ()方法用于模拟老师布置作业。

问题分析：定义接口用interface关键字，实现接口使用implements关键字

public class QuestionTwo {public static void main(String[] args) {Teacher teacher = new Teacher("王老师");Student student = new Student("张三");teacher.talk();student.talk();teacher.homework();student.homework();}}interface Lecture {public abstract void talk ();public abstract void homework ();}class Student implements Lecture {private final String name;@Overridepublic void talk() {System.out.println(this.name + "回答问题");}public Student(String name) {this.name = name;}@Overridepublic void homework() {System.out.println(this.name + "做作业");}}class Teacher implements Lecture {private final String name;@Overridepublic void talk() {System.out.println(this.name + "提出一个问题");}public Teacher(String name) {this.name = name;}@Overridepublic void homework() {System.out.println(this.name + "布置了作业");}}

实验结果

王老师提出一个问题
张三回答问题
王老师布置了作业
张三做作业

问题三

定义一个抽象接口，该接口用于求和与统计数量。定义两个奇数类与偶数类实现上述接口，分别可以求100以内的奇数的和，统计100以内的奇数个数，以及求100以内的偶数的和，统计100以内的偶数个数。

问题分析：定义接口用interface关键字，实现接口的类重写其中的抽象函数

public class QuestionThree {public static void main(String[] args) {Even even = new Even();System.out.println("100以内的偶数有" + even.count() + "个");System.out.println("100以内的偶数和为:" + even.sum());Odd odd = new Odd();System.out.println("100以内的奇数有" + odd.count() + "个");System.out.println("100以内的奇数和为:" + odd.sum());}}interface Countable {public abstract int sum ();public abstract int count ();}// 偶数class Even implements Countable {@Overridepublic int sum() {int sum = 0;for (int i = 0; i <= 100; i++) {if (i % 2 == 0) {sum += i;}}return sum;}@Overridepublic int count() {int count = 0;for (int i = 0; i <= 100; i++) {if (i % 2 == 0)count++;}return count;}}// 奇数class Odd implements Countable {@Overridepublic int sum() {int sum = 0;for (int i = 0; i <= 100; i++) {if (i % 2 != 0) {sum += i;}}return sum;}@Overridepublic int count() {int count = 0;for (int i = 0; i <= 100; i++) {if (i % 2 != 0)count++;}return count;}}

实验结果

100以内的偶数有51个
100以内的偶数和为:2550
100以内的奇数有50个
100以内的奇数和为:2500

问题四

一个抽象类动物类，同时定义抽象接口：进食接口、睡觉接口、思考接口、说话接口、行走接口、游泳接口、飞翔的接口。分别定义猫类、人类、鸟类、鱼类继承动物类，同时，根据实际情况，选择性实现上述接口，并创建实例验证。

问题分析：定义接口用interface关键字，实现接口使用implements关键字，继承类使用extends关键字，注意，接口可以多实现，类不能多继承

public class QuestionFour {public static void main(String[] args) {Cat cat = new Cat();cat.breathe();cat.eat();cat.sleep();cat.speak();cat.think();cat.walk();People people = new People();people.breathe();people.eat();people.sleep();people.speak();people.think();people.walk();people.swim();Bird bird = new Bird();bird.breathe();bird.eat();bird.sleep();bird.speak();bird.think();bird.walk();bird.fly();bird.swim();Fish fish = new Fish();fish.breathe();fish.eat();fish.sleep();fish.speak();fish.think();fish.swim();}}abstract class Animal {public abstract void breathe ();}class Cat extends Animal implements AbleToEat, AbleToSleep, Thinkable, Speakable, Walkable {@Overridepublic void breathe() {System.out.println("猫呼吸");}@Overridepublic void eat() {System.out.println("猫吃饭");}@Overridepublic void sleep() {System.out.println("猫睡觉");}@Overridepublic void think() {System.out.println("猫思考");}@Overridepublic void speak() {System.out.println("喵喵喵");}@Overridepublic void walk() {System.out.println("猫走路");}}class People extends Animal implements AbleToEat, AbleToSleep, Thinkable, Speakable, Walkable, AbleToSwim {@Overridepublic void breathe() {System.out.println("人呼吸");}@Overridepublic void eat() {System.out.println("人吃饭");}@Overridepublic void sleep() {System.out.println("人睡觉");}@Overridepublic void think() {System.out.println("人思考");}@Overridepublic void speak() {System.out.println("人说话");}@Overridepublic void walk() {System.out.println("人走路");}@Overridepublic void swim() {System.out.println("人游泳");}}class Bird extends Animal implements AbleToEat, AbleToSleep, Thinkable, Speakable, Walkable, AbleToSwim, Flyable {@Overridepublic void breathe() {System.out.println("鸟呼吸");}@Overridepublic void eat() {System.out.println("鸟吃食");}@Overridepublic void sleep() {System.out.println("鸟睡觉");}@Overridepublic void think() {System.out.println("鸟思考");}@Overridepublic void speak() {System.out.println("叽叽喳喳");}@Overridepublic void walk() {System.out.println("鸟跳");}@Overridepublic void swim() {System.out.println("鸟游泳");}@Overridepublic void fly() {System.out.println("鸟飞翔");}}class Fish extends Animal implements AbleToEat, AbleToSleep, Thinkable, Speakable, AbleToSwim {@Overridepublic void breathe() {System.out.println("鱼呼吸");}@Overridepublic void eat() {System.out.println("鱼吃食");}@Overridepublic void sleep() {System.out.println("鱼睡觉");}@Overridepublic void think() {System.out.println("鱼思考");}@Overridepublic void speak() {System.out.println("啵啵啵");}@Overridepublic void swim() {System.out.println("鱼游动");}}interface AbleToEat {public abstract void eat ();}interface AbleToSleep {public abstract void sleep ();}interface Thinkable {public abstract void think ();}interface Speakable {public abstract void speak ();}interface Walkable {public abstract void walk ();}interface AbleToSwim {public abstract void swim ();}interface Flyable {public abstract void fly ();}

实验结果