Java语言程序设计——面向抽象编程：

1、设计一个抽象类Geometry，该类包括抽象方法getArea（），用于计算面积，getCircum（）方法，用于计算周长；

2、设计一个柱状类Pillar，在类中使用抽象类声明变量，该类具有求体积方法getVolume（），用于求柱体积；具有求面积方法getAreas（），用于求柱体表面积。

3、设计类：圆，矩形，正方形，三角形；这些类继承抽象类Geometry，重写getArea（）和getCircum（）方法。

4、设计一个类AppTest，使用上转型对象来计算圆柱体积和表面积，圆柱底面半径至少10组数据；计算矩形柱的体积和表面积，矩形边长自己确定数据，数据不少于10组；同样，计算正方形柱体和三角形柱体，数据不少于10组。

Geometry类

package com.java11.abst;
public abstract class Geometry {
    public Double getArea(){
        return null;//计算面积
    }
    public Double getCircum(){
        return null;//计算周长
    }
}

Pillar类

package com.java11.abst;
public abstract class Pillar {
    public abstract Double getVolume();//计算面积
    public abstract Double getAreas();//求柱体表面积
}

圆形实现

package com.java11.geometry;
import com.java11.abst.Geometry;

public class Circle extends Geometry {
    private Double r;
    private Double PI = Math.PI;
    public Double getR() {
        return r;//半径
    }
    
    public Circle(Double r){
        this.r = r;
    }
    
    @Override
    public Double getArea() {
        return PI * r * r;
    }
    
    @Override
    public Double getCircum() {
        return 2 * PI * r;
    }
}

矩形实现

package com.java11.geometry;
import com.java11.abst.Geometry;

public class Rectangle extends Geometry {
    private Double length; //长
    private Double width;//宽
    public Double getLength() {
        return length;
    }
    public Double getWidth() {
        return width;
    }
    
    public Rectangle(Double length, Double width){
        this.length = length;
        this.width = width;
    }
    
    @Override
    public Double getArea() {
        return length * width;
    }
    
    @Override
    public Double getCircum() {
        return (length * 2) + (width * 2);
    }
}

正方形实现

package com.java11.geometry;
import com.java11.abst.Geometry;

public class Square extends Geometry {
    private Double sideLength;//边长
    public Double getSideLength() {
        return sideLength;
    }
    
    public Square(Double sideLength){
        this.sideLength = sideLength;
    }
    
    @Override
    public Double getArea() {
        return sideLength * sideLength;
    }
    
    @Override
    public Double getCircum() {
        return sideLength * 4;
    }
}

三角形实现

package com.java11.geometry;
import com.java11.abst.Geometry;

public class Triangle extends Geometry {
    private Double a;//a边
    private Double b;//b边
    private Double bottom;//c边(底)
    private Double height;//高
    public Double getA() {
        return a;
    }
    public Double getB() {
        return b;
    }
    public Double getBottom() {
        return bottom;
    }
    public Double getHeight() {
        return height;
    }
    
    public Triangle(Double a, Double b, Double bottom, Double height){
        this.a = a;
        this.b = b;
        this.bottom = bottom;
        this.height = height;
    }
    
    @Override
    public Double getArea() {
        return (bottom * height) / 2;
    }
    
    @Override
    public Double getCircum() {
        return a + b + bottom;
    }
}

正方形柱体积实现

package com.java11.pillar;
import com.java11.abst.Pillar;
import com.java11.geometry.Square;

public class Cube extends Pillar {
    E bottom;//底面积
    public Cube(E bottom){
        this.bottom = bottom;
    }
    @Override
    public Double getVolume() {
        return ((Square) bottom).getSideLength() * ((Square) bottom).getSideLength() * ((Square) bottom).getSideLength();
    }
    @Override
    public Double getAreas() {
        return 6 * ((Square) bottom).getSideLength() * ((Square) bottom).getSideLength();
    }
}

矩形柱体积实现

package com.java11.pillar;
import com.java11.abst.Pillar;
import com.java11.geometry.Rectangle;

public class Cuboid extends Pillar {
    Double height;//矩形高度
    E bottom;//底面积
    public Cuboid(E bottom, Double height){
        this.bottom = bottom;
        this.height = height;
    }
    @Override
    public Double getVolume() {
        return ((Rectangle) bottom).getArea() * height;
    }
    @Override
    public Double getAreas() {
        Double length = ((Rectangle) bottom).getLength();
        Double width = ((Rectangle) bottom).getWidth();
        return (length * width * 2) + (width * height * 2) + (length * height * 2);
    }
}

圆柱体积实现

package com.java11.pillar;
import com.java11.abst.Pillar;
import com.java11.geometry.Circle;

public class Cylinder extends Pillar {
    Double height;//圆柱体高度
    E bottom;//底面积
    public Cylinder(E bottom, Double height){
        this.bottom = bottom;
        this.height = height;
    }
    @Override
    public Double getVolume() {
        return ((Circle) bottom).getArea() * height / 3;
    }
    @Override
    public Double getAreas() {
        return (((Circle) bottom).getArea() * 2) + (((Circle) bottom).getCircum() * height);
    }
}

三角形柱体积实现

package com.java11.pillar;
import com.java11.abst.Pillar;
import com.java11.geometry.Triangle;

public class TriangularPrism extends Pillar {
    Double height;//三角形高度
    E bottom;//底面积
    public TriangularPrism(E bottom, Double height){
        this.bottom = bottom;
        this.height = height;
    }
    @Override
    public Double getVolume() {
        return ((Triangle) bottom).getArea() * height;
    }
    @Override
    public Double getAreas() {
        Double a = ((Triangle) bottom).getA();
        Double b = ((Triangle) bottom).getB();
        Double c = ((Triangle) bottom).getBottom();
        return (a * height) + (b * height) + (c * height) + (2 * ((Triangle) bottom).getArea());
    }
}

AppTest类

package com.java11;
import com.java11.geometry.Circle;
import com.java11.geometry.Rectangle;
import com.java11.geometry.Square;
import com.java11.geometry.Triangle;
import com.java11.pillar.Cube;
import com.java11.pillar.Cuboid;
import com.java11.pillar.Cylinder;
import com.java11.pillar.TriangularPrism;
import java.text.DecimalFormat;
public class AppTest {
    public static void main(String[] args) {
        calcCylinder();//圆柱体
        System.out.println("n********************************************n");
        calcCuboid();//矩形
        System.out.println("n********************************************n");
        calcCube();//正方体
        System.out.println("n********************************************n");
        calcTriangularPrism();//三角形
    }
    
    public static void calcCylinder(){
        //测试数据：半径
        Double[] rs = new Double[]{5.0,13.0,14.0,23.0,12.32,19.57,33.12,29.85,13.73,17.0};
        //测试数据：柱体高度
        Double[] heights = new Double[]{15.0,27.22,13.53,21.88,9.32,18.61,14.21,24.74,16.81,21.99};
        for(int i = 0; i < rs.length; i++){
            if(i >= heights.length){
                break;
            }
            Circle circle = new Circle(rs[i]);
            Cylinder cylinder = new Cylinder(circle,heights[i]);
            DecimalFormat df = new DecimalFormat("#.00");
            System.out.println("圆柱体第"+(i+1)+"次测试，半径："+rs[i]+"，柱体高度："+ heights[i] +"；体积：" + df.format(cylinder.getVolume()) + "；表面积：" + df.format(cylinder.getAreas()));
        }
    }
    
    public static void calcCuboid(){
        //测试数据：长
        Double[] lengths = new Double[]{5.0,31.25,13.0,21.92,23.18,25.21,17.02,15.83,29.33,31.75};
        //测试数据：宽
        Double[] widths = new Double[]{13.21,21.0,12.5,18.0,27.22,36.1,10.8,15.0,17.21,16.5};
        //测试数据：柱体高度
        Double[] heights = new Double[]{17.0,21.22,12.53,19.88,11.32,27.61,21.21,10.74,8.81,17.99};
        for(int i = 0; i < lengths.length; i++){
            if(i >= widths.length || i >= heights.length){
                break;
            }
            Rectangle rectangle = new Rectangle(lengths[i],widths[i]);
            Cuboid cuboid = new Cuboid(rectangle,heights[i]);
            DecimalFormat df = new DecimalFormat("#.00");
            System.out.println("矩形第"+(i+1)+"次测试，长："+lengths[i]+"，宽："+widths[i]+"，柱体高度："+ heights[i] +"；体积：" + df.format(cuboid.getVolume()) + "；表面积：" + df.format(cuboid.getAreas()));
        }
    }
    
    public static void calcCube(){
        //测试数据：边长
        Double[] sideLengths = new Double[]{13.21,21.0,12.5,18.0,27.22,36.1,10.8,15.0,17.21,16.5};
        for(int i = 0; i < sideLengths.length; i++){
            Square square = new Square(sideLengths[i]);
            Cube cube = new Cube(square);
            DecimalFormat df = new DecimalFormat("#.00");
            System.out.println("正方体第"+(i+1)+"次测试，边长："+sideLengths[i]+"；体积：" + df.format(cube.getVolume()) + "；表面积：" + df.format(cube.getAreas()));
        }
    }
    
    public static void calcTriangularPrism(){
        //测试数据：a边
        Double[] as = new Double[]{5.0,31.25,13.0,21.92,23.18,25.21,17.02,15.83,29.33,31.75};
        //测试数据：b边
        Double[] bs = new Double[]{13.21,21.0,12.5,18.0,27.22,36.1,10.8,15.0,17.21,16.5};
        //测试数据：c边（底边）
        Double[] bottoms = new Double[]{16.72,42.33,12.5,33.22,27.22,31.86,10.8,15.0,17.21,16.5};
        //测试数据：三角形高度
        Double[] triangleHeights = new Double[]{17.0,21.22,12.53,19.88,11.32,27.61,21.21,10.74,8.81,17.99};
        //测试数据：柱体高度
        Double[] heights = new Double[]{17.0,21.22,12.53,19.88,11.32,27.61,21.21,10.74,8.81,17.99};
        for(int i = 0; i < as.length; i++){
            if(i >= bs.length || i >= bottoms.length || i >= triangleHeights.length || i >= heights.length){
                break;
            }
            Triangle triangle = new Triangle(as[i],bs[i],bottoms[i],triangleHeights[i]);
            TriangularPrism triangularPrism = new TriangularPrism(triangle,heights[i]);
            DecimalFormat df = new DecimalFormat("#.00");
            System.out.println("三角形第"+(i+1)+"次测试，a边："+as[i]+"，b边："+bs[i]+"，c边（底边）："+bottoms[i]+"，底部高度："+triangleHeights[i]+"，柱体高度："+ heights[i] +"；体积：" + df.format(triangularPrism.getVolume()) + "；表面积：" + df.format(triangularPrism.getAreas()));
        }
    }
}

运行结果

说明面向抽象编程的优点和开闭原则在本设计中的使用情况？

答：（1）面向抽象编程的优点是具体类可从抽象类自动得到这些方法的缺省实现，使开发过程能够更加清晰和灵活。

（2）开闭原则在本次设计中的使用情况：开闭原则规定类或者方法，函数等应该对于扩展是开放的，但是对于修改是封闭的。在本次设计中，主要用于几何体的抽象实现，例如实现圆柱体的处理类时，必须要实现继承的几何体抽象类中的所有方法，但是可以在圆柱体的实现类中加自己的扩展方法，例如构造函数等。

如以上有错误的地方，请在评论区中指出，谢谢！

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Java语言程序设计——面向抽象编程：

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