Thread: Chess Program

the coorToSqi() is now in the ChessBoard class. I dont get a nullpointer exception anymore instead of the nullpointer it prints out the first square and prints out the toString() method so result "A8" upper left.

    public ChessBoard(){ 
        squares = new ArrayList<Square>();
        pieces = new ArrayList<ChessPiece>();
        addLocations();
 
        coorToSqi(0,0);
 
 
        setSquareColors();
        //makeChessPieces();
    }
 
    public Square coorToSqi(int col, int row)
   	{
   	        int index = row * NUM_OF_COLS + col;
   	        System.out.println(getSquare(index));
   	        return getSquare(index);
 
   	}

How is the progress on the FEN-notation string scanner method?

 coorToSqi(0,0);

Why does this call to the method ignore what the method returns? It should save the value in a Square variable.

i tried this but dont know what the method should return didnt get any further

package model;
 
import javax.swing.JLabel;
 
public class Fen {
 
	private String FenParser;
 
	private ChessPiece chesspiece;
 
	public Fen(){
		defaultFen();	
	}
 
	public void defaultFen(){
		FenParser = "rnbqkbnr/ppppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR";			
	}
 
	public void scanner(String str){
		FenParser = str;
	}
 
	public void scanParser(){
		for(int i = 0; i < FenParser.length(); i++){
			if(FenParser.substring(i).matches("r|n|b|q|k|p|R|N|B|Q|K|P")){
 
			}
		}
 
	}
}

Why does this call to the method ignore what the method returns? It should save the value in a Square variable.

like this?

 public Square coorToSqi(int col, int row)
   	{
   	        int index = row * NUM_OF_COLS + col;
   	        return getSquare(index);       
   	}

I described a method that you could write to work on the parsing techniques. See post#94.

What will the caller of the coorToSqi() method do with the Square object that is returned?
Why did you write that method? How will it be used?

What will the Fen class be used for?

I described a method that you could write to work on the parsing techniques. See post#94.

I did not. No idea how i could code that. The String only contains characters(string) and doesn't contain objects, how does it know the is r@r=0, c=0. And the FEN also contains numbers /8/8/8/8/

--- Update ---

Like this?

public void printCoorToSqi(){
    	for (int row = 0; row < 8; row++) {
	        for (int col = 0; col < 8; col++) {
	        	int index = row * NUM_OF_COLS + col;
	        	System.out.println(squares.get(index)+"@"+"r="+row+",c="+col);
	        }
 
    	}
}

This was the result:

A8@r=0,c=0
B8@r=0,c=1
C8@r=0,c=2
D8@r=0,c=3
E8@r=0,c=4
F8@r=0,c=5
G8@r=0,c=6
H8@r=0,c=7
A7@r=1,c=0
B7@r=1,c=1
C7@r=1,c=2
D7@r=1,c=3
E7@r=1,c=4
F7@r=1,c=5
G7@r=1,c=6
H7@r=1,c=7
A6@r=2,c=0
B6@r=2,c=1
C6@r=2,c=2
D6@r=2,c=3
E6@r=2,c=4
F6@r=2,c=5
G6@r=2,c=6
H6@r=2,c=7
A5@r=3,c=0
B5@r=3,c=1
C5@r=3,c=2
D5@r=3,c=3
E5@r=3,c=4
F5@r=3,c=5
G5@r=3,c=6
H5@r=3,c=7
A4@r=4,c=0
B4@r=4,c=1
C4@r=4,c=2
D4@r=4,c=3
E4@r=4,c=4
F4@r=4,c=5
G4@r=4,c=6
H4@r=4,c=7
A3@r=5,c=0
B3@r=5,c=1
C3@r=5,c=2
D3@r=5,c=3
E3@r=5,c=4
F3@r=5,c=5
G3@r=5,c=6
H3@r=5,c=7
A2@r=6,c=0
B2@r=6,c=1
C2@r=6,c=2
D2@r=6,c=3
E2@r=6,c=4
F2@r=6,c=5
G2@r=6,c=6
H2@r=6,c=7
A1@r=7,c=0
B1@r=7,c=1
C1@r=7,c=2
D1@r=7,c=3
E1@r=7,c=4
F1@r=7,c=5
G1@r=7,c=6
H1@r=7,c=7

The example output for scanning a FEN-notation string: r@r=0, c=0
means that a Rook(r) was located at row=0 and column=0.
That was assuming that the FEN-notation started at location 0,0 in the upper left and went to location 7,7 in the lower right.
Is that the correct way to position the pieces? Or does it start at the lower left and work to the upper right?

When scanning the string, the column value starts at 0 and increases by one as each piece is found. when a number is found, its value is used to increase the column value.

Is that the correct way to position the pieces?

yes, that is the correct way! the FEN also starts with lower case r this is the black rook.

When scanning the string, the column value starts at 0 and increases by one as each piece is found. when a number is found, its value is used to increase the column value.

and is this the right way to scan the string? O and while scanning the string the string value "r" doesnt contain a Piece object so what to do

public void scanParser(){
		for (int row = 0; row < 8; row++) {
	        for (int col = 0; col < 8; col++) 
	        	for(int i = 0; i < FenParser.length(); i++){
	        		if(FenParser.substring(i).matches("r|n|b|q|k|p|R|N|B|Q|K|P")){
 
	        		}
	        		else{
	        		col =+ Integer.parseInt(FenParser.substring(i));
	        		}
			}
		}
 
}

You can NOT use nested loops to scan the string. The scan routine should use a single loop to look at the characters in the string one at a time.

string value "r" doesnt contain a Piece object

You could define a method to "convert" a character to an piece object.

Like an iterator? -> update iterator cannot be used on a string

maybe like this?

public void scanParser(){
		for (int row = 0; row < 8; row++) {
	        for (int col = 0; col < 8; col++) 
	        	for(char c: FenParser.toCharArray()){
	        		if(c){
 
	        		}
	        		else{
	        			col += Integer.parseInt(c);
		        	}

Only one loop.

You should not try writing code BEFORE you have a design.
What are the steps the parsing code needs to do?

The parser code:

- Needs to check every character in the FenParser String.
- If a letter is found (check what kind of letter and what kind of ChessPiece belong to this letter).
- If a slash is found, do nothing.
- If a number is found the number, the number should be added to the col number.

The parser needs to know where we are in the board and place the ChessPiece on the board. The ChessPiece which belongs to the letter the parser is checking

--- Update ---

any idea how i can convert the letter to a object and place it on the board(the JLabel)?

--- Update ---

am i on the right track?

public void scanParser(){
		for (int row = 0; row < 8; row++) {
	        for (int col = 0; col < 8; col++) 
	        	for(Character c: FenParser.toCharArray()){
	        		String str = Character.toString(c);
	        		if(str.matches("r|n|b|q|k|p|R|N|B|Q|K|P")){
	        			convertLetterToPiece(str);
	        			int index = row * NUM_OF_COLS + col;
 
	        		}
	        		else{
	        			col += Integer.parseInt(str);
		        	}
	        	}
 
	     }
 
	}
 
	public ChessPiece convertLetterToPiece(String letter){
		for(int i = 0; i < 64; i++){
			if(ChessBoard.getAllPieces().get(i).equals(letter)){
				chesspiece = ChessBoard.getAllPieces().get(i);
			}
		}
		return chesspiece;
	}

- If a slash is found, do nothing.

The slash indicates the end of a row ==> The row value should be incremented.

where we are in the board

It needs to keep track of the row and column values as it scans the String.
The scan starts at row=0 and col=0. Each piece increments the col. Each slash increments the row.

convert the letter to a object

Write a method that takes a letter and returns a Piece object.

am i on the right track?

What happens when you compile and execute the code? Does it do what you want?

darn i have the code it compiles but when i run it i see the board but i dont see any pieces on the board.

Can you check the code for me? but its a lot of code

Try debugging the code by adding some println statements that print out messages showing where the code is executing and the values of variables as they are changed.
The print outs will show you what the code is doing and help you find mistakes.

Also you should do stand-alone tests of methods to be sure that they work as expected.
For example, call the FEN-notation scanning method and have it print out something that shows the pieces and the locations where each should go. Print out something like I showed in post#94.

Another test would be to call the method that puts a piece on the board and then display the board and see if the piece is there.

now i get a nullpointer

Look at the source line with the error and find the variable with the null value.

Exception in thread "main" java.lang.NullPointerException
at model.Square.getPieceImage(Square.java:53)
at view.ChessBoardView.addPiecesToContentPane(ChessBo ardView.java:89)
at view.ChessBoardView.createGUI(ChessBoardView.java: 59)
at view.ChessBoardView.<init>(ChessBoardView.java:42)
at controller.Controller.makeFrame(Controller.java:45 )
at controller.Controller.<init>(Controller.java:24)
at controller.Main.main(Main.java:9)

package model;
 
import view.assets.*;
 
import java.util.ArrayList;
 
import javax.swing.ImageIcon;
import javax.swing.JLabel;
 
public class Square{
 
	private String location;
	private String squareColor;
	private ImageIcon image;
	private ImageIcon pieceImage;
	private static ChessPiece chesspiece;
 
	private boolean empty;
 
	public Square(String location){
		this.location = location;
		empty = true;
		chesspiece = null;
	}
 
	public void setImage(ImageIcon image){
		this.image = image;
	}
 
	public ImageIcon getImage(){
		return image;
	}
 
	public boolean isEmpty(){
		return empty;	
	}
 
	public void setColor(String color){
		squareColor = color;
	}
 
	public String getColor(){
		return squareColor;
	}
 
	public String toString(){
		return location;
	}
 
	public ImageIcon getPieceImage(){
 
		if(squareColor.equals("WHITE")){
			pieceImage = chesspiece.getImageWhite(); <<<<<<<Line 53
		}
		else if(squareColor.equals("BROWN")){
			pieceImage = chesspiece.getImageBrown();
		}
		return pieceImage;
	}
 
	public void setChessPiece(ChessPiece chesspiece){
		this.chesspiece = chesspiece;
		empty = false;
		}
}

--- Update ---

package model;
 
import javax.swing.ImageIcon;
 
public class ChessPiece {
 
	private final String name;
 
    private final String letter;
 
    private final String PAWN_COLOR;
 
    private ImageIcon imageWhiteSquare;
 
    private ImageIcon imageBrownSquare;
 
	public ChessPiece(String letter, String name, String color){
		this.name = name;
		this.letter = letter;
		PAWN_COLOR = color;
	}
 
	public void setImageWhite(ImageIcon image){
		imageWhiteSquare = image;
	}
 
	public void setImageBrown(ImageIcon image){
		imageBrownSquare = image;
	}
 
	public ImageIcon getImageWhite(){
		return imageWhiteSquare;
	}
 
	public ImageIcon getImageBrown(){
		return imageBrownSquare;
	}
 
	public String getLetter(){
		return letter;
	};
}

--- Update ---

what do you think of this code

	public void scanParser(){
		for (int row = 0; row < 8; row++) {
	        for (int col = 0; col < 8; col++) 
	        	for(Character c: FenParser.toCharArray()){
	        		String str = Character.toString(c);
	        		if(str.matches("r|n|b|q|k|p|R|N|B|Q|K|P")){
	        			int index = row * NUM_OF_COLS + col;
	        			chessboard.getAllSquares().get(index).setChessPiece(convertLetterToPiece(str));
	        		}
	        		else{
	        			col += Integer.parseInt(str);
		        	}
	        	}
 
	     }
 
	}
 
	public ChessPiece convertLetterToPiece(String letter){
		for(int i = 0; i < chessboard.getAllPieces().size(); i++){
			if(ChessBoard.getAllPieces().get(i).getLetter().equals(letter)){
				chesspiece = ChessBoard.getAllPieces().get(i);
			}
		}
		return chesspiece;
	}

Exception in thread "main" java.lang.NullPointerException
at model.Square.getPieceImage(Square.java:53)

what variable on line 53 has a null value? Find the variable, then backtrack to see why it does not have a valid value.

what do you think of this code

Too many loops. There should only be one to go over the characters in the String.

This line looks weird:

chessboard.getAllSquares().get(index).setChessPiece(convertLetterToPiece(str))

Why not just call a method in chessboard with the piece and its location: setPiece(piece, row, col);

The use of index makes no sense outside of the chessboard class.
what if the squares are saved in a 2 dim array instead of an arraylist?

Exception in thread "main" java.lang.NullPointerException
at model.Fen.scanParser(Fen.java:35)
at model.Fen.<init>(Fen.java:16)
at view.ChessBoardView.<init>(ChessBoardView.java:40)
at controller.Controller.makeFrame(Controller.java:45 )
at controller.Controller.<init>(Controller.java:24)
at controller.Main.main(Main.java:9)

package model;
 
import javax.swing.JLabel;
 
 
public class Fen {
 
	private String FenParser;
 
	private static ChessBoard chessboard;
	private ChessPiece chesspiece;
	private final int NUM_OF_COLS = 8, NUM_OF_ROWS = 8;
 
	public Fen(){
		defaultFen();
		scanParser();
	}
 
	public void defaultFen(){
		FenParser = "rnbqkbnr/ppppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR";		
 
	}
 
	public void scanner(String str){
		FenParser = str;
	}
 
	public void scanParser(){
		for (int row = 0; row < 8; row++) {
	        for (int col = 0; col < 8; col++) 
	        	for(Character c: FenParser.toCharArray()){
	        		String str = Character.toString(c);
	        		if(str.matches("r|n|b|q|k|p|R|N|B|Q|K|P")){
	        			int index = row * NUM_OF_COLS + col;
	        			chessboard.coorToSqi(convertLetterToPiece(str), row, col);
	        		}
	        		else{
	        			//col += Integer.parseInt(str);
		        	}
	        	}
 
	     }
 
	}
 
	public ChessPiece convertLetterToPiece(String letter){
		for(int i = 0; i < chessboard.getAllPieces().size(); i++){
			if(ChessBoard.getAllPieces().get(i).getLetter().equals(letter)){
				chesspiece = ChessBoard.getAllPieces().get(i);
			}
		}
		return chesspiece;
	}
}

 public Square coorToSqi(ChessPiece piece, int col, int row)
   	{
   	        int index = row * NUM_OF_COLS + col;
   	        ChessBoard.getAllSquares().get(index).setChessPiece(piece);
   	        return getSquare(index);       
   	}

what if the squares are saved in a 2 dim array instead of an arraylist?

what is a 2 dim array?

Exception in thread "main" java.lang.NullPointerException
at model.Fen.scanParser(Fen.java:35)

Look at line 35 and find the variable with the null value. Then backtrack and see why it does not have a valid value.

what is a 2 dim array?

String[][] twoDim = new String[3][4]; // define a 2 dim array

NOTE: The posted code still has too many loops. Get rid of the first two for loops in scanParser.

i have no idea how and how am i going to use a two dim array actually you say throw everything away and start over

--- Update ---

i never finish this in time, can you please help me?

I did not mean for you to change your code. I was only giving an example of something to think about when defining a class. Users of that class should NOT know how the class saves its data. Converting row and col to index assumes that the class saves the data in a one dim arraylist. The natural coordinates for a piece is row and column not index. Those are the values that should be passed with the piece to the method and let the method do what needs to be done.

any idea how i can bluid that.. dont think i can do this


the program i made is not working

the program i made is not working

Work on testing each method by itself. For example the scan method. Call it with a FEN-notation string and have it find each piece and the row and column for that piece.
Then work on the setPiece method. Call it with a piece(or String), a row and a column and have it put the piece on the board at the given location and then print the board to see if the piece is in the correct location.
Then put the two together, the scan method should call the setPiece() method with each piece it finds in the FEN-notation string.

jeeeeej the FEN class works i can move pawns but when i add the images JLabel to the view i get crappy screen!

Screen Shot 2013-08-15 at 12.18.15 AM.jpg