java 中摘要类的输出有问题

Question

我正在尝试从抽象的方法中打印值 class。有一个调用抽象方法的 switch 语句和一个打印数组中项目的语句。我尝试了案例 1（添加新圆）然后案例 6（显示形状。

可能是说明符或案例 6 中的调用语句有问题？

package lab8;
import java.util.Scanner;
public class test {
public static void main(String args[])
{
    // DATA
    Shape[] shapes = new Shape[10];
    int nextIDNumber = 1;
    boolean exit = false;
    int selection;
    Scanner input = new Scanner(System.in);
    int id;
    double x, y;
    double base = 0, height = 0, width = 0, radius = 0, scaleFactor;
    boolean found = false;

    // ALGORITHM
    // loop until user exits
    do
    {
        // display menu
        System.out.println("1 Add a new circle");
        System.out.println("2 Add a new rectangle");
        System.out.println("3 Add a new right triangle");
        System.out.println("4 Delete a shape");
        System.out.println("5 Delete all shape");
        System.out.println("6 Display all shapes");
        System.out.println("7 Move a shape");
        System.out.println("8 Enter a scale factor");
        System.out.println("9 Scale all shapes");
        System.out.println("10 Exit program");

        // get user choice
        selection = input.nextInt();
        while (selection < 1 || selection > 10)
        {
            System.out.println("Please enter valid choice");
            selection = input.nextInt();
        }

        // switch on selection
        switch(selection)
        {
        case 1:
            // ADD NEW CIRCLE
            System.out.println("Enter radius for your circle: ");
            radius = input.nextDouble();
            // get size from user (one variable)

            // get location from user (two variables)
            System.out.println("Enter x location for your circle: ");
            x = input.nextDouble();
            System.out.println("Enter y location for your circle: ");
            y = input.nextDouble();
            // set found to false
            found = false;
            for(int i = 0; i < shapes.length; i++) {
                if (shapes[i] == null) {
                    shapes[i] = new Circle (nextIDNumber++, x, y, radius);
                    found = true;
                    break;
                }
            }
            if(!found) {
                System.out.println("Array is full. ERROR");
            }
            break;

            // loop through array
                // if this is not a valid object
                    // create new Circle object and assign to current array element

                    // set found to true

                    // break out of loop

            // if not found, give error message

            // break out of switch statement

        case 2:
            // ADD NEW RECTANGLE
            // get size from user (two variables)
            System.out.println("Enter height of rectagle: ");
            height = input.nextDouble();
            System.out.println("Enter width of rectagle: ");
            width = input.nextDouble();
            // get location from user (two variables)
            System.out.println("Enter x location for your rectangle: ");
            x = input.nextDouble();
            System.out.println("Enter y location for your rectangle: ");
            y = input.nextDouble();
            // set found to false
            found = false;
            
            for (int i = 0; i< shapes.length;i++) {
                if(shapes[i] != null) {
                    shapes[i] = new Rectangle(nextIDNumber++, x,y, height, width);
                    found = true;
                    break;
                }
            }
            if(!found) {
                System.out.println("ERROR");
            }
            break;
            
        case 3:
            // ADD NEW RIGHT TRIANGLE
            // get size from user (two variables)
            System.out.println("Enter the base: ");
            base = input.nextDouble();
            while (base <= 0)
            {
                System.out.println("Invalid number, please enter positive number");
                base = input.nextDouble();
            }

            System.out.println("Enter the height");
            height = input.nextDouble();
            while (height <= 0)
            {
                System.out.println("Invalid number, please enter positive number");
                height = input.nextDouble();
            }

            // get location from user (two variables)
            System.out.println("Enter X location");
            x = input.nextDouble();
            while (x < 0)
            {
                System.out.println("Invalid number, please enter positive number or zero");
                x = input.nextDouble();
            }

            System.out.println("Enter Y location");
            y = input.nextInt();
            while (y < 0)
            {
                System.out.println("Invalid number, please enter positive number or zero");
                y = input.nextDouble();
            }

            // set found to false
            found = false;

            // loop through array
            for (int i = 0; i < shapes.length; i++)
            {
                // if this is not a valid object
                if (shapes[i] == null)
                {
                    // create new RightTriangle object and assign to current array element
                    shapes[i] = new RightTriangle(nextIDNumber++, x, y, base, height);
                    // set found to true
                    found = true;

                    // break out of loop
                    break;
                }
            }

            // if not found, give error message
            if (!found)
            {
                System.out.println("No more room");
            }

            // break out of switch statement
            break;

        case 4:
            // DELETE ONE SHAPE
            // get id number to delete
            System.out.println("Enter ID of shape to be deleted: ");
            id = input.nextInt();
            found = false;
            for (int i = 0; i< shapes.length; i++) {
                if (id == shapes[i].getID() && shapes[i] != null) {
                    shapes[i] = null;
                    found = true;
                    break;
                }
            }
            if (!found) {
                System.out.println("Shape not found.");
            }
            break;

        case 5:
            // DELETE ALL SHAPES
            System.out.println("Are you sure you want to delete all shapes? 1] YES 2] NO : ");
            int choice = input.nextInt();
            if(choice == 1) {
                for (int i= 0; i<shapes.length; i++) {
                    if(shapes[i]!=null) {
                        shapes[i] = null;
                    }
                }
            }
            break;
        case 6:
            // DISPLAY ALL SHAPES
            // print header
            System.out.println("Here are our shapes");
            System.out.printf("%10s %10s %10s %10s %10s\n", "ID", "X", "Y", "AREA", "PERIMETER");
            for (int i = 0; i<shapes.length;i++) {
                if (shapes[i] != null) {
                    System.out.printf("%10d %10.2f %10.2f %10.2f %10f\n", shapes[i].getID(),shapes[i].getxLoc(),shapes[i].getyLoc(),shapes[i].getArea(),
                    shapes[i].getPerimiter() );
                    
                    
                    }
            }
            break;
            

        case 7:
            // MOVE A SHAPE
            System.out.println("Enter the ID of shape:");
            id = input.nextInt();
            System.out.println("Enter X location of shape:");
            x = input.nextDouble();
            System.out.println("Enter Y location of shape:");
            y = input.nextDouble();
            found = false;
            for(int i =0; i<shapes.length;i++) {
                if(id == shapes[i].getID() && shapes[i] != null) {
                    shapes[i].setxLoc(x);
                    shapes[i].setxLoc(y);
                    found = true;
                    break;
                }
            }
            if (!found) {
                System.out.println("Not found.");
            }
            break;
            
        case 8:
            // ENTER A SCALE FACTOR
            System.out.println("Enter scale factor: ");
            scaleFactor = input.nextDouble();
            Shape.setScaleFactor(scaleFactor);
            break;
            
            // get scale factor

            // call SetScaleFactor to set the new scale factor

            // break out of switch statement

        case 9:
            // SCALE ALL SHAPES
            for(int i =0;i<shapes.length;i++) {
                if (shapes[i] != null) {
                    shapes[i].scaleShape();
                }
            }
            
            // loop through array
                // if this is a valid object
                    // call ScaleShape

            // break out of switch statement
            break;

        case 10:
            System.out.println("Do you want to exit? \n1] YES\n2] NO");
            int user = input.nextInt();
            if(user == 1) {
                System.out.println("Thank you!");
                exit = true;
            }
            
            break;
            // EXIT PROGRAM
            // confirm user wants to exit
                // set variable to break out of loop

            // break out of switch statement
        }

    } while (!exit);

}

}

abstract class Shape
{
    // declare static variable
    public static double scaleFactor;

    // declare instance variables
    private int id;
    private double xLoc;
    private double yLoc;
    
    // one constructor
    public Shape(int i, double x, double y) {
        i = id;
        x = xLoc;
        y = yLoc;
        }

    // get/set methods
    public static double getScaleFactor() {
        return scaleFactor;
    }
    public static void setScaleFactor(double scaleFactor) {
        if (scaleFactor > 0) {
            Shape.scaleFactor = scaleFactor;
        }
    }
    public int getID() {
        return id;
    }
    public void setID(int i) {
        if (i > 0 ) {
            i = id;
        }
    }
    public double getxLoc() {
        return xLoc;
    }
    public void setxLoc(double x) {
        x = xLoc;
    }
    public double getyLoc() {
        return yLoc;
    }
    public void setyLoc(double y) {
        y = yLoc;
    }

    // abstract methods
    public abstract double getArea();
    public abstract double getPerimiter();
    public abstract void scaleShape();
    
}

class Circle extends Shape
{
    // declare instance variable
    private double radius;
    
    public Circle (int i, double x, double y, double r){
        super(i, x, y);
        r = radius;
    }

    // get/set methods
    public double getRadius()
    {
        return radius;
    }
    public void setRadius(double r)
    {
        if (r > 0.0)
        {
            radius = r;
        }
    }

    // override abstract methods
    // GetPerimeter method
    public  double getPerimiter() {
        return 2 * Math.PI * radius;
    }

    // GetArea method
    public double getArea() {
        return Math.PI * radius * radius;
    }


    // ScaleShape method
    public void scaleShape() {
        radius = radius * scaleFactor;
        setRadius(radius);
        
    }
    }

Answer 1

你的构造函数中的赋值错误，所以与你的形状关联的值都是零。您需要将它们切换过来。这个构造函数：

// one constructor
public Shape(int i, double x, double y) {
    i = id;
    x = xLoc;
    y = yLoc;
}

应该是这样的：

public Shape(int i, double x, double y) {
    id = i;
    xLoc = x;
    yLoc = y;
}

还有这个：

    public Circle (int i, double x, double y, double r){
    super(i, x, y);
    r = radius;
}

应该是这样的：

public Circle (int i, double x, double y, double r){
    super(i, x, y);
    radius = r;
}

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