Java 矩形类面积/周长输出0

Question

当我运行 Rectangle.java 时，我可以获得矩形中输入的长度和宽度，但是当我尝试使用 getter 计算面积/周长时，我得到的结果为零

我尝试添加和删除 setter，在 getArea 和 getPerimeter 中放入 getter/setter 方法，但似乎没有任何效果

//Code provided by the teacher as a template 
Rectangle temp = new Rectangle();
        temp.print();
        System.out.println();

        temp.setLength(2.5);
        temp.setWidth(3.0);
        //Consider how your rectangle will change after setting the length and width to specific values.
        temp.print();

        System.out.println();

        Rectangle r = new Rectangle(3.5,2);
        r.print();




//My Class

public class Rectangle 
{
    private static double length;
    private static double width;
    private static double perimeter;
    private static double area;

    public Rectangle(double length, double width)
    {
        setLength(length);
        setWidth(width);
    }

    public Rectangle()
    {

    }

    public static double getLength() 
    {
        return length;
    }
    public static void setLength(double length) 
    {
        Rectangle.length = length;
    }
    public static double getWidth() 
    {
        return width;
    }
    public static void setWidth(double width)
    {
        Rectangle.width = width;
    }   
    public static double getPerimeter(double length, double width) 
    {
        return 2*width+2*length;
    }

    public static double getArea(double length, double width) 
    {
        area= getLength()*getWidth();
        return length*width;
    }


    public static String print() 
    {
        String Rectangle = new String();
        System.out.println("This rectangle has a length of "+length+" and a width of "+width);
        System.out.println("The area of the rectangle is: "+ area);
        System.out.println("The perimeter of the rectangle is: "+ perimeter);
        return Rectangle;

    }
}

没有错误消息。

输出:

该矩形的长度为 0.0，宽度为 0.0矩形面积为:0.0矩形的周长为:0.0

这个矩形的长度为 2.5，宽度为 3.0矩形面积为:0.0矩形的周长为:0.0

这个矩形的长度为 3.5，宽度为 2.0矩形面积为:0.0矩形的周长为:0.0

Answer 1

您需要更改打印方法并调用周长和面积方法，以便这些变量获得所需的值

 public static String print() 
{
    getPerimeter(length,width);
    getArea(length,width);
    String Rectangle = new String();
    System.out.println("This rectangle has a length of "+length+" and a width of "+width);
    System.out.println("The area of the rectangle is: "+ area);
    System.out.println("The perimeter of the rectangle is: "+ perimeter);
    return Rectangle;

}

我建议不要使用静态关键字，因为值不会绑定(bind)到对象