参照类图创建一个Rectangle类，包含以下属性和方法: 2) 属性:两个double成员变量，width和height; 3) 不带参数的构造方法:width和height的初始值分别是6和8:带参的构造方法 4) 方法:计算并输出矩形的周长方法名为fndPremeter 0: 5) 编写测试类，应用不同的构造方法创建至少三个Rectangle的对象，分别调用周 长和面积的方法。 类图如下:

+----------------+
|    Rectangle   |
+----------------+
| - width: double |
| - height: double|
+----------------+
| + Rectangle()   |
| + Rectangle(w: double, h: double)|
| + findPerimeter(): void|
+----------------+

Rectangle.java

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

    public Rectangle() {
        this.width = 6;
        this.height = 8;
    }

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

    public void findPerimeter() {
        double perimeter = 2 * (width + height);
        System.out.println("The perimeter of the rectangle is " + perimeter);
    }
}

RectangleTest.java

public class RectangleTest {
    public static void main(String[] args) {
        Rectangle rectangle1 = new Rectangle();
        rectangle1.findPerimeter(); // Output: The perimeter of the rectangle is 28.0

        Rectangle rectangle2 = new Rectangle(10, 20);
        rectangle2.findPerimeter(); // Output: The perimeter of the rectangle is 60.0

        Rectangle rectangle3 = new Rectangle(5.5, 7.5);
        rectangle3.findPerimeter(); // Output: The perimeter of the rectangle is 26.0
    }
}