设计一个矩形类,有长和宽两个属性.java

// 矩形
public class RectangleDemo {

    public static void main(String[] args) {
        RectangleDemo demo = new RectangleDemo(12, 32);
        
        System.out.println(demo.getPerimeter());
        System.out.println(demo.getArea());
        
        demo = new RectangleDemo();
        
        System.out.println(demo.getArea());
        System.out.println(demo.getPerimeter());
        
        demo.setHeight(50);
        demo.setWidth(30);
        
        System.out.println(demo.getArea());
        System.out.println(demo.getPerimeter());
    }

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

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

    public RectangleDemo(double height, double width) {
        this.height = height;
        this.width = width;
    }

    public RectangleDemo() {
        this.height = 10;
        this.width = 10;
    }

    private double height;// 高度
    private double width;// 宽度

    public double getHeight() {
        return height;
    }

    public void setHeight(double height) {
        this.height = height;
    }

    public double getWidth() {
        return width;
    }

    public void setWidth(double width) {
        this.width = width;
    }

}

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Rectangle {

//矩形的宽
static double width;

//矩形的长
static double length;

//矩形周长
double circumference;

//矩形面积
double area;

public double circumference(double width,double length){

circumference =2* width + 2*length;
return circumference;
}

public double area(double width,double length){

area = width*length;
return area;
}

/**
* @param args
* @throws IOException
*/
public static void main(String[] args) {
// TODO Auto-generated method stub

//创建矩形的对象
Rectangle rectangle = new Rectangle();

//带缓冲区的读取器
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

try {

//输入矩形的长
System.out.println("请输入矩形的长：");
length =Double.parseDouble(br.readLine());

//输入矩形的宽
System.out.println("请输入矩形的宽：");
width = Double.parseDouble(br.readLine()) ;

} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

System.out.println("矩形的周长为：" + rectangle.circumference(width, length));
System.out.println("矩形的面积为：" + rectangle.area(width, length));
}
}