java-用抽象类shape表示一般图形

Question

定义一个抽象类shape ，用来表示一般图形。shape具有属性name，表示图形的名字，如三角形、矩形、圆形，抽象方法area和perimeter，分别用来计算形状的面积和周长。（1）定义一个Rectangle类继承shape类，定义矩形的属性width和height，并实现两个抽象方法计算矩形的面积和周长，并覆盖toString方法。定义一个Circle类继承shape类，定义圆形的属性半径R，并实现两个抽象方法计算圆形的面积和周长，并覆盖toString方法。要求Circle类不能派生子类。定义测试类，在main（）方法中创建shape数组，其中创建一个Rectangle类对象和一个Circle类对象，并输出对象信息，计算图形的面积和周长。

Answer 1

package praticeJava;

public abstract class Shape{
    private String name;

    protected Shape() {
        
    }
    
    protected Shape(String name) {
        this.name = name;
    }
    
    @Override
    public String toString() {
        return "Shape [name=" + name;
    }

    public abstract double getArea();

    public abstract double getPerimeter();
}

package praticeJava;
public class Circle extends Shape {
    private double radius;
    public Circle() {

    }
    public Circle(double radius, String name) {
       super(name);
       this.radius=radius;
    }
    public double getArea() {
        return radius * radius * Math.PI;
    }
    public double getPerimeter() {
        return 2 * radius * Math.PI;
    }
    @Override
    public String toString() {
        return super.toString()+",radius=" + radius + ", Area=" + getArea() + ",Perimeter=" + getPerimeter() + "]";
    }
    
}

package praticeJava;

public class Rectangle extends Shape {
    private double width;
    private double height;

    public Rectangle() {
    }

    public Rectangle(double width, double height, String name) {
        super(name);
        this.width = width;
        this.height = height;

    }

    public double getArea() {
        return width * height;
    }

    public double getPerimeter() {
        return 2 * (width + height);
    }

    @Override
    public String toString() {
        return super.toString() + ",width=" + width + ", height=" + height + ", Area=" + getArea() + ",Perimeter="
                + getPerimeter() + "]";
    }
}

package praticeJava;

public class Test {
    public static void main(String[] args) {
        Shape shape[]=new Shape[10];
        shape[0]=new Circle(3.0,"圆");
        shape[1]=new Rectangle(2.0,3.0,"矩形");
        System.out.println(shape[0]);
        System.out.println(shape[1]);
    }
}

运行截图