需要在一个从另一个类扩展的类中设置一个变量。 或覆盖类型

Question

Why do I keep failing this test?

Test Cube(1.0, 1.0, 1.0) sets the type to "Cube",

width, length and height each to 1.0 Test feedback

Expected: Cube, 1.0, 1.0, 1.0

Yours: Rectangle, 1.0, 1.0, 1.0

I need the cube class to be able to set its type to Cube. Right now it seems to be setting itself to Rectangle. My main fills an Array of Shapes, I then have methods to count the different types of shapes according to the Type of each shape. How can I define Cube as a shape, when my rectangle class already extends shape, but I MUST have my Cube class extend rectangle. It must because I need to have access to the area as well and the length and width.

I also have a very simple interface that is implemented by my cube. It is just to find the volume. Can I somehow utilize my interface to override the type?

Can't find an answer on StackOverflow to this specific question.

Here is my Rectangle class

public class Rectangle extends Shape {
    protected double width;
    protected double length;

    public Rectangle(double width, double length) {
        super("Rectangle");
        setWidth(width);
        setLength(length);
    }// end ctr 

    public final double getWidth  () {return width; }
    public final double getLength () {return length;}

    public final void setWidth (double width) {
        if (width < 0) {
            System.out.println("Value could not be updated due to negative double.");
        }else
            this.width = width;
    }// end width setter 

    public final void setLength (double length) {
        if (length < 0) {
            System.out.println("Value could not be updated due to negative double.");
        }else
            this.length = length;
    }// end length setter 

    @Override
    public double area() {
        return length * width;
    }// end area method

    public double perimeter() {
        return 2 * (length + width);
    }// end perimeter method 

    @Override
    public String toString() {
        String str = "";

        str += String.format("%10s", "Rectangle:") + " ";
        str += "width: " + String.format("%.1f", width) + ", " + "length: " + String.format("%.1f", length);
        str += ", " + "area: " + String.format("%.2f", area() ) + ", ";
        str += "perimeter: " + String.format("%.2f", perimeter() );

        return str;
    }// end descriptor 

}// end rect class 

Here is my Cube class

public class Cube extends Rectangle implements Shape3D  {
    protected double height;

    public Cube (double width, double length, double height) {
        super(width, length);
        setHeight(height);
    }// end ctr

    public final double getHeight () {return height;} // end get height 

    public final void setHeight (double height) {
        if (height < 0) {
            System.out.println("Value could not be updated due to negative double.");
        }else
            this.height = height;
    }// end set height 

    @Override
    public double volume () {
        return super.area() * height;
    } // end volume method

     @Override
    public String toString() {
        String str = "";

        str += String.format("%10s", "Cube:") + " ";
        str += "width: " + String.format("%.1f", width) + ", " + "length: " + String.format("%.1f", length);
        str += ", " + "area: " + String.format("%.2f", area() ) + ", ";
        str += "perimeter: " + String.format("%.2f", perimeter() );
        str += ", height: " + String.format("%.1f", height );
        str += ", volume: " + String.format("%.1f", volume() );

        return str;
    }// end descriptor 
}// end cube class 

The Rectangle class comes from my Shape class,

public abstract class Shape {
    protected String type;

    public Shape (String type) {
        setType(type);
    }// end ctr

    public final String getType ()            {return type;     }
    public final void setType   (String type) {this.type = type;}

    public abstract double area (); // end prototype

    public double getArea () {return area();}

    @Override
    public String toString() {
        String str = "";

        str += type;

        return str;
    }// end descriptor 

}// end shape class

Answer 1

Your cube class uses super to call rectangle's constructor which in turn calls the Shape class's constructor with the string "Rectangle", basically as you have it, the cube constructor will not allow you to set its type of cube. You will need to explicitly use the setType method.

You could in cube's constructor add the line

this.setType("Cube");

and it should work (have not tested).