java创建矩形类Rectangle,以及测试类RectangleTest

Rectangle类：

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

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

    public double getWidth() {
        return width;
    }

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

    public double getHeight() {
        return height;
    }

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

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

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

RectangleTest类：

public class RectangleTest {
    public static void main(String[] args) {
        Rectangle r1 = new Rectangle(4, 6);
        System.out.println("Width: " + r1.getWidth());
        System.out.println("Height: " + r1.getHeight());
        System.out.println("Area: " + r1.getArea());
        System.out.println("Perimeter: " + r1.getPerimeter());

        r1.setWidth(5);
        r1.setHeight(7);
        System.out.println("Width: " + r1.getWidth());
        System.out.println("Height: " + r1.getHeight());
        System.out.println("Area: " + r1.getArea());
        System.out.println("Perimeter: " + r1.getPerimeter());
    }
}

输出结果：

Width: 4.0
Height: 6.0
Area: 24.0
Perimeter: 20.0
Width: 5.0
Height: 7.0
Area: 35.0
Perimeter: 24.0