Блог

Я работаю над программой для стека блинов, которая создаст стопку блинов и позволит пользователю выбрать блин, который перевернет стопку из этого блина выше. Пользователь будет делать это до тех пор, пока блины не будут заказаны по размеру. (Скриншот показывает, как это должно выглядеть) Программа для стека блинов

У меня возникли проблемы при использовании элементов из стека блинов, получающих java.lang.ClassCastException: [Ljava.lang.Объект; не может быть приведен к [Ljava.lang.Сопоставимая ошибка.

Я думал, что определил PancakeStack только для хранения сопоставимых объектов Pancake, но, похоже, программа видит все в стеке как несопоставимые объекты.

Класс Блинов

 import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;

/**
 *
 * @author leo-nard
 */
public class Pancake implements Comparable<Pancake>
{
    private Color colour;
    private int size;
    private int select;
    private Color ogColour;
    private int height = 20;
    
    public Pancake(int size, Color c)
    {
        this.size = size;
        this.colour = ogColour = c;
    }
  
    @Override
    public int compareTo(Pancake o) 
    {
        //find size of Pancake object which compareTo was called through
        int xSize = this.getSize();
        //find size of pancake we are comparing to (input parameter)
        int ySize = o.getSize();
        
        //print size difference as integer interpritation
        if(xSize > ySize)
        {
            return 1;
        }
        else if(xSize < ySize)
        {
            return -1;
        }
        else if(xSize == ySize)
            return 0;
        return 0;
    }
    
    public int getSize()
    {
        return size;
    }
    
    public void highlight(boolean selected)
    {
        if(selected)
            this.colour = Color.RED;
        if(!selected)
            this.colour = ogColour;
    }
    
    public void draw(Graphics g)
    {
        Graphics2D g2d = (Graphics2D) g;
        g2d.drawRoundRect(10, 50, 150, 150, 50, 30); // to draw a rounded rectangle.
    }

}
 

Класс блинов

 import java.awt.Color;
import java.util.*;

/**
 *
 * @author leo-nard
 * @param <Pancake>
 */
public class PancakeStack<Pancake extends Comparable<Pancake>> extends ArrayStack<Pancake>
{
    
    public PancakeStack()
    {
        super();
        numElements = 0;
    }
    
    PancakeStack(Collection<? extends Pancake> c)
    {
        this();
        for(Pancake element:c)
        {
            push(element);
        }
    }
    
    public Pancake obtainPancake(int index)
    {
        if(isEmpty())
        {
            throw new NoSuchElementException("There are no Pancakes in the Stack.");
        }
        else if(index > numElements || index< 0)
            throw new NoSuchElementException("There are no Pancakes in the stack at this index.");
        
        Pancake p = elements[index]; 
        return p;
    }
    
    public int findMax(int i)
    {
        int index = 0;
        int max = 0;
        Iterator<Pancake> it = iterator();
        Pancake current = elements[i];
        Pancake largest = current;
        if(isEmpty())
            throw new NoSuchElementException("There are no Pancakes in the Stack");
        else
        {
            while(it.hasNext())
            {
                current = it.next();
                if(current.compareTo(largest) == 1 amp;amp; index >= i)
                {
                    largest = current;
                    max = i;
                }
                else
                    index  ;
            }

            return max;
        }
        
    }
 

PancakeGUI

 import java.awt.BorderLayout;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;

/**
 *
 * @author leo-nard
 */
public class PancakeGUI extends JPanel implements ActionListener
{
    private DrawPanel drawPanel;
    private JButton resetButton, resolveButton;
    private Pancake singlePancake;
    private PancakeStack<Pancake> stack;
    private Timer timer;
    
    
    public PancakeGUI()
    {
        super(new BorderLayout());
        
        stack  = new PancakeStack<Pancake>();
        
        JPanel southPanel = new JPanel();
        
        resetButton = new JButton("Reset");
        resetButton.addActionListener(this);
        southPanel.add(resetButton);
        
        resolveButton = new JButton("Resolve");
        resolveButton.addActionListener(this);
        southPanel.add(resolveButton);
        
        drawPanel = new DrawPanel();
        
        add(southPanel, BorderLayout.SOUTH);
        add(drawPanel, BorderLayout.NORTH);
        
        timer = new Timer(20, this);
        timer.start();
    }
    
    private class DrawPanel extends JPanel
    {
        public DrawPanel()
        {
            setBackground(Color.WHITE);  
            setPreferredSize(new Dimension(500,500));           
        }
        
        @Override
        public void paintComponent(Graphics g)
        {
            super.paintComponent(g);
            Color c = new Color(255, 0, 0);
            Pancake p = new Pancake(10, c);
            stack.push(p);
            
            //pancake.draw(g);
            
        }
    } 
    
    @Override
    public void actionPerformed(ActionEvent e) 
    {
        
    }
    
    public static void main(String[] args) 
    {
        JFrame frame = new JFrame("Pancake Sort Problem");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(new PancakeGUI());
        frame.pack();
        // position the frame in the middle of the screen
        Toolkit tk = Toolkit.getDefaultToolkit();
        Dimension screenDimension = tk.getScreenSize();
        Dimension frameDimension = frame.getSize();
        frame.setLocation((screenDimension.width-frameDimension.width)/2,
           (screenDimension.height-frameDimension.height)/2);
        frame.setVisible(true);
        
        //Something while the main thread is still alive
        for (int i=0; i<20; i  )
        {  System.out.println("Main thread counting: "   i);
           try
           {  
               Thread.sleep(500); // delay for 500ms
           }
           catch (InterruptedException e)
           {}
        }
        
        PancakeStack<Pancake> stack = new PancakeStack<Pancake>();
        System.out.println(stack.getClass());
        Color c = new Color(255, 0, 0);
        Pancake p1 = new Pancake(1, c);
        Pancake p2 = new Pancake(2, c);
        Pancake p3 = new Pancake(3, c);
        Pancake p4 = new Pancake(4, c);
        Pancake p5 = new Pancake(5, c);
        Pancake p6 = new Pancake(6, c);
        Pancake p7 = new Pancake(7, c);
        Pancake p8 = new Pancake(8, c);
        Pancake p9 = new Pancake(9, c);
        Pancake p10 = new Pancake(10, c);
        Object p11 = new Pancake(11, c);
        stack.push(p3);
        stack.push(p7);
        stack.push(p6);
        stack.push(p10);
        stack.push(p5);
        stack.push(p9);
        stack.push(p2);
        stack.push(p8);
        stack.push(p4);
        System.out.println(stack.obtainPancake(2));
    }

   
}
 

Массив

 import java.util.Collection;
import java.util.NoSuchElementException;

public class ArrayStack<E> implements StackADT<E>
{
   private final int INITIAL_CAPACITY = 20;
   protected int numElements;
   protected E[] elements;
   
   // default constructor that creates a new stack 
   // that is initially empty
   public ArrayStack()
   {  numElements = 0;
      elements = (E[])(new Object[INITIAL_CAPACITY]); // unchecked
   }
   
   // constructor for creating a new stack which
   // initially holds the elements in the collection c
   public ArrayStack(Collection<? extends E> c)
   {  this();
      for (E element : c)
         push(element);
   }

   // Adds one element to the top of this stack
   public void push(E element)
   {  if (numElements >= elements.length)
         expandCapacity();
      elements[numElements  ] = element;
   }
   
   // removes and returns the top element from this stack
   public E pop() throws NoSuchElementException
   {  if (numElements > 0)
      {  E topElement = elements[numElements-1];
         elements[numElements-1] = null;
         numElements--;
         return topElement;
      }
      else
         throw new NoSuchElementException();
   }
   
   // returns without removing the top element of this stack
   public E peek() throws NoSuchElementException
   {  if (numElements > 0)
         return elements[numElements-1];
      else
         throw new NoSuchElementException();
   }
   
   // returns true if this stack contains no elements
   public boolean isEmpty()
   {  
       return (numElements==0);
   }
   
   // returns the number of elements in this stack
   public int size()
   {  
       return numElements;
   }
   
   // returns a string representation of the stack from top to bottom
   public String toString()
   {  
       String output = "[";
      for (int i=numElements-1; i>=0; i--)
      {  output  = elements[i];
         if (i>0)
            output  = ",";
      }
      output  = "]";
      return output;
   }
      
   // helper method which doubles the current size of the array
   private void expandCapacity()
   {  
       E[] largerArray =(E[])(new Object[elements.length*2]);//unchecked
      // copy the elements array to the largerArray
      for (int i=0; i<numElements; i  )
         largerArray[i] = elements[i];
      elements = largerArray;
   }
}
 

Ошибка возникает в строке 43 PancakeStack — Pancake p = элементы[индекс];
где я пытаюсь назначить блин из моего стека другой переменной блина