java实验2 对象、类、继承、包

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本文通过一系列Java实验展示了对象、类、继承和包的使用。实验包括：创建位于不同包中的Point类，实现计算距离和移动方法；定义圆类并利用Point类实现；创建Person和Student类，展示继承和方法；实现复数类，完成复数运算；以及定义抽象类Shape和其子类（圆形、矩形、梯形），每个类都有计算面积的方法，并进行了测试验证。

（1）声明位于包test.exam中Point类，有坐标x、y两个私有成员变量，有一个返回与其它点的距离的方法，还有一个移动点的方法

package com.qst.fuxi;
public class Point {
    double x;
    double y;
    public Point() {
    
    }
    public Point(double x, double y) {
        super();
        this.x = x;
        this.y = y;
    }
    public double getX() {
        return x;
    }
    public void setX(double x) {
        this.x = x;
    }
    public double getY() {
        return y;
    }
    public void setY(double y) {
        this.y = y;
    }
    public void movePoint(double dx,double dy) {
           System.out.println("移动前的坐标为:"+this.x+this.y);
           System.out.println("移动量:"+dx+dy);
           this.x+=dx;
           this.y+=dy;
           System.out.println("移动后的坐标为:"+this.x+this.y);
       }
}
测试函数
1、返回与其它点的距离    
package com.qst.fuxi;
import java.util.Scanner;
import java.math.*;
public class PointDemo {
    Point p1;
    Point p2;
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入第一个点的x值x1");
        Double x1 = scanner.nextDouble();
        System.out.println("请输入第一个点的y值y1");
        Double y1 = scanner.nextDouble();
        System.out.println("请输入第二个点的x值x2");
        Double x2 = scanner.nextDouble();
        System.out.println("请输入第二个点的y值y2");
        Double y2 = scanner.nextDouble();
        Point p1 = new Point(x1, y1);
        Point p2 = new Point(x2, y2);
        PointDemo pd2= new PointDemo(p1,p2);
        pd2.distance()；
    }
    public void distance() {
      Double a=Math.sqrt(Math.abs(p1.getX()-p2.getX())*Math.abs(p1.getX()-p2.getX())+Math.abs(p1.getY()-p2.getY())*Math.abs(p1.getY()-p2.getY()));
      System.out.println(a);
    }
    public PointDemo() {
        super();
    }
    public PointDemo(Point p1, Point p2) {
        super();
        this.p1 = p1;
        this.p2 = p2;
    }
    public Point getP1() {
        return p1;
    
    public void setP1(Point p1) {
        this.p1 = p1;
    }
    public Point getP2() {
        return p2;
    }
    public void setP2(Point p2) {
        this.p2 = p2;
    }
}
2、移动点    
package com.qst.fuxi;
public class PointMove {
        public double x;
        public double y;
        public static void main(String[] args) {
        Point p1=new Point(1.0,2.0);
        Point p2=new Point(3.0,4.0);
        p1.movePoint(p2.x,p2.y);    
        }
}

运行结果：

（2）声明一个位于包test.abc中的圆类，圆由圆心和半径组成，有一个计算面积的方法，利用1中的类实现圆类，写一个测试类用于测试1中的点类和2中的圆类

package com.qst.fuxi;
public class CircleArea {
        // 成员变量
        private int r; // 变量可以Scanner输入数据
        private double PI = 3.14; // double接收
        // 构造方法（无参构造方法）
        public void Circle() {
        }
        public void setR(int r) {
            this.r = r;
        }
        // 定义一个getArea方法将来求圆的面积
        public void getArea() {
            System.out.println("圆的面积为：" + (PI * r * r));
        }
        // 定义一个getGirth方法将来求圆的面积
        public void getGirth() {
            System.out.println("圆的周长为：" + (2 * PI * r));
        }
    }
测试函数
package com.qst.fuxi;
import java.util.Scanner;
public class  Circle {
    public static void main(String[] args) {    
        Scanner sc = new Scanner(System.in); // 创建对象
        System.out.println("请输入圆的半径为：");
        int radius = sc.nextInt(); // 接收数据
        CircleArea c = new CircleArea();
        c.setR(radius);
        c.getArea();
        c.getGirth();
    }
}

运行结果：

（3）Person类有姓名属性，说出姓名方法，Student类除了有姓名，还有学号、专业和成绩属性及设置和输出成绩等方法，定义这两个类并用测试类进行测试


1、Person类
package text;
public class Person {
    private String name;
    //创建构造器
    public Person(String name){
        this.name = name;
        }
    //进行封装
    public String getName() {
         return name;
         }
    public void setName(String name) {
        this.name = name;
        }
    //建立一个talk方法对个人信息进行输出
     public void talk(){
     System.out.println("学生信息"+"\n学生姓名："+name);
     }
}
2、Student类
package text;
public class Student extends Person {
     //添加student类的属性  学号 专业  成绩  
     private String sno;
     private String major;
     private double score;
     //创建student类的构造器
     public Student(String name,String sno,String major,double score){
     super( name);
     this.sno=sno;
     this.major=major;
     this.score = score; 
     }
     //封装student类的属性
     public String getsno() {
     return sno;
     }
     public void setsno(String sno) {
         this.sno=sno;
     }
     public String getmajor() {
     return major;
     }
     public void setmajor(String major) {
     this.major = major;
     }
     public double getscore() {
         return score;
         }
     public void score(double score) {
        this.score=score;
        }
     public static void sort(Student[] stus) {//数组方法
            Student temp;
            for (int i = 0; i<stus.length-1;i++) {//冒泡比较
                for (int j=0;j<stus.length-i-1;j++) {
                    if (stus[j].score < stus[j+1].score) {
                        temp=stus[j];
                        stus[j]=stus[j+1];
                        stus[j+1]=temp;
                    }
                }
            }
     }     
     //重写talk()方法
     public void talk() {
     super.talk();
     System.out.println("学号:"+sno);
     System.out.println("专业:"+major);
     System.out.println("成绩:"+score);
     }
    }
3、测试类
package text;
import java.util.Scanner;
public class studentInformation {
    
        @SuppressWarnings("resource")
        public static void main(String [] args){
            @SuppressWarnings("unused")
            Scanner input=new Scanner(System.in);
            System.out.print("请输入要录入的学生个数：");
            int numStudent=new Scanner(System.in).nextInt();
            Student[] stus = new Student[numStudent];
            
        //录入学生信息
        System.out.println("按要求输入学生信息");
        for(int i=0;i<numStudent;i++) {
            System.out.print("依次输入第"+(i+1)+"个学生的姓名学号专业成绩：");
            stus[i]=new Student(new Scanner(System.in).next(),new Scanner(System.in).next(),new Scanner(System.in).next(),new Scanner(System.in).nextDouble());
        }
        //调用排序方法
        Student.sort(stus);
        
        System.out.println("成绩录入完成，下面将按成绩的降序排序输出学生信息");
        System.out.println("------------------------------------------------------");
            
        //按成绩降序输出学生信息
        for (Student stu : stus) {
            stu.talk();
        }
    }
}

运行结果：

（4）编写一个复数类，具有实部、虚部成员变量，可以完成加、减、乘、获得实部和虚部等操作，并编写一个主类对其进行测试。

package complexTest;
import java.util.Scanner;
public class Complex { // 复数类
    double real;  // 实部
    double image; // 虚部
    
    Complex(){  // 不带参数的构造方法
        @SuppressWarnings("resource")
        Scanner input = new Scanner(System.in);
        double real = input.nextDouble();
        double image = input.nextDouble();
        Complex1(real,image);
    }
 
    public void Complex1( double real, double image) { // 供不带参数的构造方法调用
        this.real = real;
        this.image = image;
    }
 
    public Complex(double real,double image){ // 带参数的构造方法
        this.real = real;
        this.image = image;
    }
 
    public double getReal() {
        return real;
    }
 
    public void setReal(double real) {
        this.real = real;
    }
 
    public double getImage() {
        return image;
    }
 
    public void setImage(double image) {
        this.image = image;
    }
    
    Complex add(Complex a){ // 复数相加
        double real2 = a.getReal();
        double image2 = a.getImage();
        double newReal = real + real2;
        double newImage = image + image2;
        Complex result = new Complex(newReal,newImage);
        return result;
    }
    
    Complex sub(Complex a){ // 复数相减
        double real2 = a.getReal();
        double image2 = a.getImage();
        double newReal = real - real2;
        double newImage = image - image2;
        Complex result = new Complex(newReal,newImage);
        return result;
    }
    
    Complex mul(Complex a){ // 复数相乘
        double real2 = a.getReal();
        double image2 = a.getImage();
        double newReal = real*real2 - image*image2;
        double newImage = image*real2 + real*image2;
        Complex result = new Complex(newReal,newImage);
        return result;
    }
    
    public void print(){ // 输出
        if(image > 0){
            System.out.println(real + " + " + image + "i");
        }else if(image < 0){
            System.out.println(real + "" + image + "i");
        }else{
            System.out.println(real);
        }
    }
}
测试类
package complexTest;
public class ComplexTest { // 用于测试复数类
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        System.out.println("请用户输入第一个复数的实部和虚部:");
        Complex data1 = new Complex();
        System.out.println("请用户输入第二个复数的实部和虚部:");
        Complex data2 = new Complex();
       
        // 以下分别为加减乘 
        Complex result_add = data1.add(data2);
        Complex result_sub = data1.sub(data2);
        Complex result_mul = data1.mul(data2);
        
        result_add.print();
        result_sub.print();
        result_mul.print();
    }
}

运行结果：

（5）定义一个抽象类Shape，该类有抽象方法area，圆形、矩形、梯形等均是一种Shape，也都有自己求area方法，定义这些类并写测试类进行测试

package area;
//抽象类
abstract class Shape 
{
 public abstract Double calculateShape();
}
//Rectangle类
 class Rectangle extends  Shape
{
  private double length;
  private double width;    
 public Rectangle(double length, double width)
 {
     this.length = length;
     this.width = width;
 }
 public double getLength() 
 {
     return length;
 }public void setLength(double length) 
 {
     this.length = length;
 }
 public double getWidth() 
 {
     return width;
 }public void setWidth(double width)
 {
     this.width = width;
 }
 //继承Shape类，实现getArea()方法
 public Double getArea() 
 {
     return width*length;
 }
public Double calculateShape() {
    // TODO 自动生成的方法存根
    return null;
}
}
 //Circle类
class Circle extends Shape
{
 private double radius;

   public Circle(double radius) 
   {
       this.radius = radius;
   }
   public double getRadius()
   {
       return radius;
   }
   public void setR(double radius) 
   {
       this.radius = radius;
   }
   //继承Shape类，实现getArea()方法
   public Double getArea() 
   {
       return Math.PI*radius*radius;
   }
public Double calculateShape() {
    // TODO 自动生成的方法存根
    return null;
}    
}

//trapezoid类
class Trapezoid  extends  Shape
{
 private double high;
 private double width1;
 private double width2;
public Trapezoid(double high, double width1,double width2)
{
    this.high =high;
    this.width1 = width1;
    this.width2 = width2;
}
public double getHigh() 
{
    return high;
}public void setHigh(double high) 
{
    this. high =  high;
}
public double getWidth1() 
{
    return width1;
}public void setWidth1(double width1)
{
    this.width1 = width1;
}
public double getWidth2() 
{
    return width2;
}public void setWidth2(double width2)
{
    this.width2 = width2;
}
//继承Shape类，实现Area()方法
public Double getArea() 
{
    return (width1+width2)*high/2;
}
public Double calculateShape() {
    // TODO 自动生成的方法存根
    return null;
}
}

测试类
package area;

import java.util.Scanner;

class Main {
     public static void main(String[] args) {
         Scanner sc=new Scanner(System.in);
         System.out.println("输出圆的半径：");
         double radius=sc.nextDouble();
         Circle circle=new Circle(radius);
         System.out.println("半径为:"+circle.getRadius()+"的圆面积为:"+circle.getArea());
         
         System.out.println("\n输出矩形的长和宽：");
         double length=sc.nextDouble();
         double width=sc.nextDouble();
         Rectangle rectangle=new Rectangle(length,width);
         System.out.println("长为:"+rectangle.getLength()+"宽为:"+rectangle.getWidth()+"的长方形面积为:"+rectangle.getArea()); 
         
         System.out.println("\n输出梯形的高和上边、下边：");
         double high=sc.nextDouble();
         double width1=sc.nextDouble();
         double width2=sc.nextDouble();
         Trapezoid trapezoid=new Trapezoid(high,width1,width2);
         
         System.out.println("高为:"+trapezoid.getHigh()+"上边为:"+trapezoid.getWidth1()+"下边为:"+trapezoid.getWidth2()+"的梯形面积为:"+trapezoid.getArea());       
     }
     
 }

运行结果：