Working out chess piece location / piece name

Hi guys,

I'm making a chess game for a project at uni. I have all the pieces laid out on a board and they move freely. I am now trying to get the game to understand what each piece is and the rules behind each piece.

The code so far for the game (layout and movement) is:

Code:

---

import java.io.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
 
public class ChessGame extends JFrame implements MouseListener, MouseMotionListener {
    JLayeredPane layeredPane;
    JPanel chessBoard;
    JLabel chessPiece;
    int xAdjustment;
    int yAdjustment;
       
       
 
    public ChessGame(){
        Dimension boardSize = new Dimension(600, 600);
 
        //  Use a Layered Pane for this this application
 
        layeredPane = new JLayeredPane();
        getContentPane().add(layeredPane);
        layeredPane.setPreferredSize(boardSize);
        layeredPane.addMouseListener(this);
        layeredPane.addMouseMotionListener(this);

               
               
               
        //Add a chess board to the Layered Pane
 
        chessBoard = new JPanel();
        layeredPane.add(chessBoard, JLayeredPane.DEFAULT_LAYER);
        chessBoard.setLayout( new GridLayout(8, 8) );
        chessBoard.setPreferredSize( boardSize );
        chessBoard.setBounds(0, 0, boardSize.width, boardSize.height);
               
                Color Green = new Color(119,170,119);
                Color Cream = new Color(250,235,215);
 
        for (int i = 0; i < 64; i++) {
            JPanel square = new JPanel( new BorderLayout() );
            chessBoard.add( square );
 
            int row = (i / 8) % 2;
            if (row == 0)
                square.setBackground( i % 2 == 0 ? Green : Cream );
            else
                square.setBackground( i % 2 == 0 ? Cream : Green );
        }
               
               
                /** Pieces for the board */
               
                //  Image String array - TOP ROWS

          String[] ImageArray_TOP = new String[16];

          ImageArray_TOP[0] = "pieces/top/1brook.gif";
          ImageArray_TOP[1] = "pieces/top/1bknight.gif";
          ImageArray_TOP[2] = "pieces/top/1bbishop.gif";
          ImageArray_TOP[3] = "pieces/top/1bqueen.gif";
          ImageArray_TOP[4] = "pieces/top/1bking.gif";
          ImageArray_TOP[5] = "pieces/top/1bbishop.gif";
          ImageArray_TOP[6] = "pieces/top/1bknight.gif";
          ImageArray_TOP[7] = "pieces/top/1brook.gif";
         
          ImageArray_TOP[8] = "pieces/top/1bpawn.gif";
          ImageArray_TOP[9] = "pieces/top/1bpawn.gif";
          ImageArray_TOP[10] = "pieces/top/1bpawn.gif";
          ImageArray_TOP[11] = "pieces/top/1bpawn.gif";
          ImageArray_TOP[12] = "pieces/top/1bpawn.gif";
          ImageArray_TOP[13] = "pieces/top/1bpawn.gif";
          ImageArray_TOP[14] = "pieces/top/1bpawn.gif";
          ImageArray_TOP[15] = "pieces/top/1bpawn.gif";
         
          // Image String Array - BOTTOM ROWS
       
                  String[] ImageArray_BOTTOM = new String[16];
               
          ImageArray_BOTTOM[0] = "pieces/bottom/rpawn.gif";       
          ImageArray_BOTTOM[1] = "pieces/bottom/rpawn.gif";
          ImageArray_BOTTOM[2] = "pieces/bottom/rpawn.gif";
          ImageArray_BOTTOM[3] = "pieces/bottom/rpawn.gif";
          ImageArray_BOTTOM[4] = "pieces/bottom/rpawn.gif";
          ImageArray_BOTTOM[5] = "pieces/bottom/rpawn.gif";
          ImageArray_BOTTOM[6] = "pieces/bottom/rpawn.gif";
          ImageArray_BOTTOM[7] = "pieces/bottom/rpawn.gif";

          ImageArray_BOTTOM[8] = "pieces/bottom/rrook.gif";
          ImageArray_BOTTOM[9] = "pieces/bottom/rknight.gif";
          ImageArray_BOTTOM[10] = "pieces/bottom/rbishop.gif";
          ImageArray_BOTTOM[11] = "pieces/bottom/rqueen.gif";
          ImageArray_BOTTOM[12] = "pieces/bottom/rking.gif";
          ImageArray_BOTTOM[13] = "pieces/bottom/rbishop.gif";
          ImageArray_BOTTOM[14] = "pieces/bottom/rknight.gif";
          ImageArray_BOTTOM[15] = "pieces/bottom/rrook.gif";       
               
        // Add pieces to the board (TOP)
               
                for( int i = 0; i < 16; i++) {
               
        JLabel piece = new JLabel( new ImageIcon(ImageArray_TOP[i]) );
        JPanel panel = (JPanel)chessBoard.getComponent(i);
        panel.add(piece);
       
                }
               
                // Add pieces to the board (BOTTOM)
                int inc = 48;
                for( int j = 0; j < 16; j++, inc++) {
               
        JLabel piece = new JLabel( new ImageIcon(ImageArray_BOTTOM[j]) );
        JPanel panel = (JPanel)chessBoard.getComponent(inc);
        panel.add(piece);
       
                }
               
    }
       
       
 
    public void mousePressed(MouseEvent e){
        chessPiece = null;
        Component c =  chessBoard.findComponentAt(e.getX(), e.getY());
               
                int X = e.getX();
                int Y = e.getY();
                System.out.println(X + Y);
               
                Pieces.workoutloc(X, Y);
        if (c instanceof JPanel)
        return;
       
               
 
        Point parentLocation = c.getParent().getLocation();
        xAdjustment = parentLocation.x - e.getX();
        yAdjustment = parentLocation.y - e.getY();
        chessPiece = (JLabel)c;
        chessPiece.setLocation(e.getX() + xAdjustment, e.getY() + yAdjustment);
        chessPiece.setSize(chessPiece.getWidth(), chessPiece.getHeight());
        layeredPane.add(chessPiece, JLayeredPane.DRAG_LAYER);
    }
 
    //Move the chess piece around
 
    public void mouseDragged(MouseEvent me) {
        if (chessPiece == null) return;
               
               
        chessPiece.setLocation(me.getX() + xAdjustment, me.getY() + yAdjustment);
               
    }
 
  //Drop the chess piece back onto the chess board
 
    public void mouseReleased(MouseEvent e) {
        if(chessPiece == null) return;
 
 
        chessPiece.setVisible(false);
               
        Component c =  chessBoard.findComponentAt(e.getX(), e.getY());
 
        if (c instanceof JLabel){
            Container parent = c.getParent();
            parent.remove(0);
            parent.add( chessPiece );
        }
        else {
            Container parent = (Container)c;
            parent.add( chessPiece );
        }
 
        chessPiece.setVisible(true);
    }
 
    public void mouseClicked(MouseEvent e) {
       
    }
    public void mouseMoved(MouseEvent e) {
  }
    public void mouseEntered(MouseEvent e){
       
    }
    public void mouseExited(MouseEvent e) {
       
    }
 
    public static void main(String[] args) {
        JFrame frame = new ChessGame();
               
       
                JMenuBar MenuBar = new JMenuBar();
                JMenu File = new JMenu("File" );       
                JMenu Help = new JMenu( "Help" );
                MenuBar.add( File );
                MenuBar.add( Help );

                JMenuItem newGame = new JMenuItem( "New Game" );
                JMenuItem exit = new JMenuItem( "Exit" );
                File.add( newGame );
                File.add( exit );
                JMenuItem HelpInfo = new JMenuItem( "How to play chess" );
                JMenuItem About = new JMenuItem( "About" );
                Help.add( HelpInfo );
                Help.add( About );
               
               
                // ActionListeners for items
               
                // EXIT PROGRAM
               
                ActionListener ExitGame = new ActionListener() {
                        public void actionPerformed( ActionEvent actionEvent ) {
                                System.exit(0);
                        }       
                };
               
                // NEW GAME
               
                ActionListener newGameAction = new ActionListener() {
                        public void actionPerformed( ActionEvent actionEvent ) {
                               
                                // SOMETHING
                               
                        }
                };       
               
                // HOW TO PLAY
               
                ActionListener HowToPlay = new ActionListener() {
                        public void actionPerformed( ActionEvent actionEvent ) {
                                String url = "http://www.chess.com/learn-how-to-play-chess.html";
                try        {
                        java.awt.Desktop.getDesktop().browse(java.net.URI.create(url));
                                } catch (IOException ex) {
                                        System.err.println(); }
                       
                        }
                };       
                // ADD LISTENERS
               
                exit.addActionListener( ExitGame );
                newGame.addActionListener( newGameAction );
                HelpInfo.addActionListener( HowToPlay );
               
               
               
                frame.setJMenuBar( MenuBar );
                frame.setDefaultCloseOperation(DISPOSE_ON_CLOSE );
                frame.pack();
                frame.setResizable(false);
                frame.setLocationRelativeTo( null );
                frame.setVisible(true);
                frame.setSize(600, 645);
    }
}

---

Okay so that is the main class to make the board and add pieces / movement.

Here is the code I have so far to make an array of piece names and make a 'pseudoboard' so the game knows where each piece is.

In the ChessGame class there is a method

Code:

---

Pieces.workoutloc(X, Y);

---

which I hope will pass the co-ordinates from the mouse click which will work out what piece has been clicked and whether it is allowed to move or not.

workoutloc is inside the piece class which I have here:

Code:

---

public class Pieces {

public static void main(String Args[]) {



String[] piecePlaces = new String[65];

        piecePlaces[0] = "WR1";
        piecePlaces[1] = "WH1";
        piecePlaces[2] = "WB1";
        piecePlaces[3] = "WK";
        piecePlaces[4] = "WQ";
        piecePlaces[5] = "WR2";
        piecePlaces[6] = "WB2";
        piecePlaces[7] = "WH2";
        piecePlaces[8] = "WR2";
        piecePlaces[9] = "WPAWN1";
        piecePlaces[10] = "WPAWN2";
        piecePlaces[11] = "WPAWN3";
        piecePlaces[12] = "WPAWN4";
        piecePlaces[13] = "WPAWN5";
        piecePlaces[14] = "WPAWN6";
        piecePlaces[15] = "WPAWN7";
        piecePlaces[16] = "WPAWN8";
       
        piecePlaces[17] = null;
        piecePlaces[18] = null;
        piecePlaces[19] = null;
        piecePlaces[20] = null;
        piecePlaces[21] = null;
        piecePlaces[22] = null;
        piecePlaces[23] = null;
        piecePlaces[24] = null;
        piecePlaces[25] = null;
        piecePlaces[26] = null;
        piecePlaces[27] = null;
        piecePlaces[28] = null;
        piecePlaces[29] = null;
        piecePlaces[30] = null;
        piecePlaces[31] = null;
        piecePlaces[32] = null;
        piecePlaces[33] = null;
        piecePlaces[34] = null;
        piecePlaces[35] = null;
        piecePlaces[36] = null;
        piecePlaces[37] = null;
        piecePlaces[38] = null;
        piecePlaces[39] = null;
        piecePlaces[40] = null;
        piecePlaces[41] = null;
        piecePlaces[42] = null;
        piecePlaces[43] = null;
        piecePlaces[44] = null;
        piecePlaces[45] = null;
        piecePlaces[46] = null;
        piecePlaces[47] = null;
        piecePlaces[48] = null;
       
        piecePlaces[49] = "BPAWN1";
        piecePlaces[50] = "BPAWN2";
        piecePlaces[51] = "BPAWN3";
        piecePlaces[52] = "BPAWN4";
        piecePlaces[53] = "BPAWN5";
        piecePlaces[54] = "BPAWN6";
        piecePlaces[55] = "BPAWN7";
        piecePlaces[56] = "BPAWN8";
        piecePlaces[57] = "BR1";
        piecePlaces[58] = "BH1";
        piecePlaces[59] = "BB1";
        piecePlaces[60] = "BK";
        piecePlaces[61] = "BQ";
        piecePlaces[62] = "BB2";
        piecePlaces[63] = "BH2";
        piecePlaces[64] = "BR2";
       
       
        int rows = 8;
        int cols = 8;
        int start = 0;
        int start2 = 0;
       
        int[][] pseudoboard = new int[cols][cols];

        for (int row = 0; row < rows; row++) {
                for(int col = 0; col < cols; col++) {
               
                start++;
        }
               
                start2++;
        }       
       
       
        workoutloc(int x,int y)        {
        int temp1 = x / 75;
        int        temp2 = y / 75;
        math.round(temp1);
        math.round(temp2);
       
        // lets assume the 2 dimentional array of 8x8 exists already name pseudoboard and contains integers from [0][0]-->0 [8][8]-->64
        // what you do is

    int targetsquare = pseudoboard[temp1][temp2];       
       
       
        }
       
        }
}

---

I don't know how to create the 2 dimentional array so that it will accept the X & Y from the main ChessGame class, divide the coordinate by 75 (75 being the width / height of the square) and then round it up or down to a whole number so that it can be placed into the array.

I've hit a wall that I don't think I can get myself away from without a poke... I'm pretty new to programming and this is just giving me a real headache!

If anyone could help I would really appreciate it!

thanks,

Dan

Would something like this work?

Code:

---

int column = 0;
int row = 0;

if(x >= 0 && x <= 600){
    column = x / 75
}else{
    //mouse not on game board
}

if(y >= 0 && y <= 600){
    row = y / 75
}else{
    //mouse not on game board
}

---

If x=100 and y=100, column would be 1, and row would be 1.

Why does piecePlaces[] have 65 elements?

Sorry for the late reply, thanks snotmare, that worked :D

I accidentally had one too many pieces in the array however I've corrected that now!

So the ChessGame class has not changed yet, here is the Pieces class:

Code:

---

public class Pieces extends ChessGame {


public Pieces() {

}
       
       
public static void workoutloc(int X, int Y) {
                int column = X;
                int row = Y;
               
        String[] piecePlaces = new String[64];

        piecePlaces[0] = "WR1";
        piecePlaces[1] = "WH1";
        piecePlaces[2] = "WB1";
        piecePlaces[3] = "WK";
        piecePlaces[4] = "WQ";
        piecePlaces[5] = "WB2";
        piecePlaces[6] = "WH2";
        piecePlaces[7] = "WR2";
        piecePlaces[8] = "WPAWN1";
        piecePlaces[9] = "WPAWN2";
        piecePlaces[10] = "WPAWN3";
        piecePlaces[11] = "WPAWN4";
        piecePlaces[12] = "WPAWN5";
        piecePlaces[13] = "WPAWN6";
        piecePlaces[14] = "WPAWN7";
        piecePlaces[15] = "WPAWN8";
       
        piecePlaces[16] = null;
        piecePlaces[17] = null;
        piecePlaces[18] = null;
        piecePlaces[19] = null;
        piecePlaces[20] = null;
        piecePlaces[21] = null;
        piecePlaces[22] = null;
        piecePlaces[23] = null;
        piecePlaces[24] = null;
        piecePlaces[25] = null;
        piecePlaces[26] = null;
        piecePlaces[27] = null;
        piecePlaces[28] = null;
        piecePlaces[29] = null;
        piecePlaces[30] = null;
        piecePlaces[31] = null;
        piecePlaces[32] = null;
        piecePlaces[33] = null;
        piecePlaces[34] = null;
        piecePlaces[35] = null;
        piecePlaces[36] = null;
        piecePlaces[37] = null;
        piecePlaces[38] = null;
        piecePlaces[39] = null;
        piecePlaces[40] = null;
        piecePlaces[41] = null;
        piecePlaces[42] = null;
        piecePlaces[43] = null;
        piecePlaces[44] = null;
        piecePlaces[45] = null;
        piecePlaces[46] = null;
        piecePlaces[47] = null;
       
        piecePlaces[48] = "BPAWN1";
        piecePlaces[49] = "BPAWN2";
        piecePlaces[50] = "BPAWN3";
        piecePlaces[51] = "BPAWN4";
        piecePlaces[52] = "BPAWN5";
        piecePlaces[53] = "BPAWN6";
        piecePlaces[54] = "BPAWN7";
        piecePlaces[55] = "BPAWN8";
        piecePlaces[56] = "BR1";
        piecePlaces[57] = "BH1";
        piecePlaces[58] = "BB1";
        piecePlaces[59] = "BK";
        piecePlaces[60] = "BQ";
        piecePlaces[61] = "BB2";
        piecePlaces[62] = "BH2";
        piecePlaces[63] = "BR2";
       
        int start = 0;
        int start2 = 0;
       
        int[][] pseudoboard = new int[8][8];

        for (int rows = 0; rows < 8; rows++) {
                for(int cols = 0; cols < 8; cols++) {       
                        start++;
                }       
                        start2++;
                }               
               
        if(X >= 0 && X <= 600) {
                column = X / 75;
        }else{
                        //mouse not on game board
        }

        if(Y >= 0 && Y <= 600) {
                row = Y / 75;
        }else{
                    //mouse not on game board
        }       
       
        // lets assume the 2 dimencional array of 8x8 exists already name pseudoboard and contains integers from [0][0]-->0 [8][8]-->64
        // what you do is

//    int targetsquare = pseudoboard[column][row];       
       
       
        }
       
}

---

So now I think I need to link the piecePlaces array and the pseudoboard array. I'm stuck!

If anyone could help it would be great I have two weeks left to finish this and its driving me insane!!!

you could've just held a reference to the piece object in each board square...

here's an example of what i mean:

Code:

---

//the GUI board
java.awt.Canvas[][] boardArray = new java.awt.Canvas[8][8]();
//attach event to each square
for (int i=0; i<boardArray.length; i++) for (int j=0; j<boardArray[i].length; j++)
    boardArray[i][j].addMouseListener(new java.awt.event.MouseAdapter() {
            public void mousePressed(java.awt.event.MouseEvent evt) {
                boardObjectPicked(i, j, evt);
            }
            public void mouseReleased(java.awt.event.MouseEvent evt) {
                boardObjectReleased(i, j, evt);
            }
        });

---

Code:

---

    private void boardObjectPressed(int x, int y, java.awt.event.MouseEvent evt) {
        //pick up object related to board[x][y]
        updateBoard();
    }

    private void boardObjectReleased(int x, int y, java.awt.event.MouseEvent evt) {
        //if any object is picked, drop object at board[x][y]
        updateBoard();
    }

---

then the indexes x and y would relate to an array of the placement of Piece Objects, like this:

Code:

---

Piece[][] pieceArrangement = new Piece[8][8];
//initialise board when game is started
pieceArrangement[0][0] = player2.getRook1();
pieceArrangement[0][1] = player2.getHorse1();
pieceArrangement[0][2] = player2.getBishop1();
...
pieceArrangement[8][8] = player1.getRook2();

---

and you will need to rearrange the array as needed to relate to the new board with an updateBoard() method

Code:

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public void updateBoard() {
    //first check if move is valid, or if anything died
    evaluateBoard();
}

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thankyou ozzyman, it makes sense kind of but I think if I change my code drastically now I'll cause myself more work! If I had more time I would def change it, thankyou for the advice though!