需要在从另一个 class 扩展的 class 中设置一个变量。或者覆盖类型

Question

为什么我总是无法通过此测试？

Test Cube(1.0, 1.0, 1.0) 设置类型为 "Cube",

宽、长、高各为1.0 测试反馈

预期：立方体，1.0、1.0、1.0

你的：矩形、1.0、1.0、1.0

我需要立方体 class 才能将其类型设置为立方体。现在它似乎将自己设置为矩形。我主要填充一个形状数组，然后我有方法根据每个形状的类型来计算不同类型的形状。当我的矩形 class 已经扩展形状，但我必须让我的立方体 class 扩展矩形时，我如何将立方体定义为形状。一定是因为我还需要访问该区域以及长度和宽度。

我的多维数据集也实现了一个非常简单的界面。只是为了找到音量。我能以某种方式利用我的界面来覆盖类型吗？

无法在 Whosebug 上找到此特定问题的答案。

这是我的矩形 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

这是我的魔方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

矩形 class 来自我的形状 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

您的多维数据集 class 使用 super 调用矩形的构造函数，后者又调用使用字符串 "Rectangle" 构造 class 的构造函数，基本上就像您拥有的那样，立方体构造函数不允许您设置其立方体类型。您将需要明确使用 setType 方法。

您可以在多维数据集的构造函数中添加行

this.setType("Cube");

它应该工作（尚未测试）。

需要在从另一个 class 扩展的 class 中设置一个变量。或者覆盖类型

Need to set a variable in a class which is extended from another class. Or override the type

java

overriding

extends

implements