package newsatranc; 
   
   
      import java.awt.BorderLayout; 
      import java.awt.Color; 
      import java.awt.ComponentOrientation; 
      import java.awt.Cursor; 
      import java.awt.GridLayout; 
      import java.awt.event.InputEvent; 
      import java.awt.image.BufferedImage; 
      import java.io.IOException; 
      import java.io.InputStream; 
      import java.util.Map; 
      import java.util.TreeMap; 
        
      import javax.imageio.ImageIO; 
      import javax.swing.ImageIcon; 
      import javax.swing.JButton; 
      import javax.swing.JFrame; 
      import javax.swing.JLabel; 
      import javax.swing.JOptionPane; 
      import javax.swing.JPanel; 
      import javax.swing.JToolBar; 
      import java.awt.Dimension; 
        
      public class NewSatranc extends JFrame { 
        
              private static final long serialVersionUID = 1L; 
        
              private JPanel jContentPane = null; 
        
              private JPanel jPanel = null; 
        
              private JToolBar tlbMain = null; 
        
              private JLabel lblCells[] = new JLabel[64]; 
              
              private String jPieces[][] = new String[8][8];  //  @jve:decl-index=0: 
        
              private JButton btnNewGame = null; 
        
              private JLabel lblStatus = null; 
              
              private int heldX, heldY, heldI = -1; 
              
              // Map the full names of the pieces to their codenames (wRook, wQueen, etc.) 
              private Map pieceName = new TreeMap();  //  @jve:decl-index=0: 
        
              private JLabel lblCurrPlayer = null; 
              
              // Stores the current player's move - we can easily match it against 
              // the first character of the pieces array 
              private char currPlayer = ' '; 
        
              private JButton btnUndo = null; 
              
              private int[][] moves = new int[10][6]; 
              
              private String movedPieces[] = new String[10]; 
              
              private int currMove = 0; 
        
              /** 
               * This is the default constructor 
               */ 
              public NewSatranc() { 
                      super(); 
                      initialize(); 
                      buildBoard(); 
              } 
              
              /** 
               * This method initializes btnUndo      
               *       
               * @return javax.swing.JButton 
               */ 
              private JButton getBtnUndo() { 
                      if (btnUndo == null) { 
                              btnUndo = new JButton(); 
                              btnUndo.setText("Undo"); 
                              btnUndo.setEnabled(false); 
                              btnUndo.addMouseListener(new java.awt.event.MouseAdapter() { 
                                      public void mouseReleased(java.awt.event.MouseEvent e) { 
                                              undoMove(); 
                                      } 
                              }); 
                      } 
                      return btnUndo; 
              } 
        
              public static void main( String args[] ) { 
                      new NewSatranc().setVisible(true); 
              } 
        
              /** 
               * This method initializes this 
               * 
               * @return void 
               */ 
              private void initialize() { 
                      this.setSize(671, 555); 
                      this.setContentPane(getJContentPane()); 
                      this.setTitle("Basic Chess"); 
                      this.setExtendedState(JFrame.MAXIMIZED_BOTH); 
              } 
        
              /** 
               * This method initializes jContentPane 
               * 
               * @return javax.swing.JPanel 
               */ 
              private JPanel getJContentPane() { 
                      if (jContentPane == null) { 
                              jContentPane = new JPanel(); 
                              jContentPane.setLayout(new BorderLayout()); 
                              jContentPane.add(getJPanel(), BorderLayout.CENTER); 
                              jContentPane.add(getTlbMain(), BorderLayout.NORTH); 
                      } 
                      return jContentPane; 
              } 
        
              /** 
               * This method initializes jPanel        
               *       
               * @return javax.swing.JPanel    
               */ 
              private JPanel getJPanel() { 
                      if (jPanel == null) { 
                              GridLayout gridLayout = new GridLayout(); 
                              gridLayout.setRows(8); 
                              gridLayout.setHgap(5); 
                              gridLayout.setVgap(5); 
                              gridLayout.setColumns(8); 
                              jPanel = new JPanel(); 
                              jPanel.setLayout(gridLayout); 
                              //buildBoard(); 
                      } 
                      return jPanel; 
              } 
              
              private void newGame() 
              { 
                      resetBoard(); 
                      resetPieces(); 
              } 
              
              private void resetPieces() 
              { 
                      jPieces = new String[8][8]; 
                      jPieces[0][0] = "bRook"; 
                      jPieces[0][1] = "bKnight"; 
                      jPieces[0][2] = "bBishop"; 
                      jPieces[0][3] = "bKing"; 
                      jPieces[0][4] = "bQueen"; 
                      jPieces[0][5] = "bBishop"; 
                      jPieces[0][6] = "bKnight"; 
                      jPieces[0][7] = "bRook"; 
                      jPieces[1][0] = "bPawn"; 
                      jPieces[1][1] = "bPawn"; 
                      jPieces[1][2] = "bPawn"; 
                      jPieces[1][3] = "bPawn"; 
                      jPieces[1][4] = "bPawn"; 
                      jPieces[1][5] = "bPawn"; 
                      jPieces[1][6] = "bPawn"; 
                      jPieces[1][7] = "bPawn"; 
                      
                      jPieces[6][0] = "wPawn"; 
                      jPieces[6][1] = "wPawn"; 
                      jPieces[6][2] = "wPawn"; 
                      jPieces[6][3] = "wPawn"; 
                      jPieces[6][4] = "wPawn"; 
                      jPieces[6][5] = "wPawn"; 
                      jPieces[6][6] = "wPawn"; 
                      jPieces[6][7] = "wPawn"; 
                      jPieces[7][0] = "wRook"; 
                      jPieces[7][1] = "wKnight"; 
                      jPieces[7][2] = "wBishop"; 
                      jPieces[7][3] = "wKing"; 
                      jPieces[7][4] = "wQueen"; 
                      jPieces[7][5] = "wBishop"; 
                      jPieces[7][6] = "wKnight"; 
                      jPieces[7][7] = "wRook"; 
                      RepaintPieces(); 
              } 
              
              private void PaintPiece(String pieceName, int i) 
              { 
                      try 
                      { 
                              if(pieceName != null && pieceName != "") 
                              { 
                                      InputStream inIcon = ClassLoader.getSystemResourceAsStream("pociu/games/chess/" + pieceName + ".png"); 
                                      BufferedImage imgIcon = ImageIO.read(inIcon); 
                                      lblCells[i].setIcon(new ImageIcon(imgIcon)); 
                                      //System.out.println("Painted " + pieceName + " at " + i); 
                              } 
                              else 
                              { 
                                      lblCells[i].setIcon(null); 
                                      //System.out.println("Cleared cell at " + i); 
                              } 
                      } 
                      catch(IOException e) 
                      { 
                              e.printStackTrace(); 
                      } 
              } 
              
              private void RepaintPieces() 
              { 
                      int i = 0; 
                      for(int x = 0; x < 8; x++) 
                      { 
                              for(int y = 0; y < 8; y++) 
                              { 
                                      if(jPieces[x][y] != null && !jPieces[x][y].equals("")) 
                                      { 
                                              PaintPiece(jPieces[x][y], i); 
                                      } 
                                      else 
                                      { 
                                              PaintPiece("", i); 
                                      } 
                                      i++; 
                              } 
                      } 
              } 
              
              private void ClearHlight(int i, int rowNum) 
              { 
                      if((i + rowNum) % 2 == 0) 
                      { 
                              lblCells[i].setBackground(Color.WHITE); 
                      } 
                      else 
                      { 
                              lblCells[i].setBackground(Color.GRAY); 
                      } 
              } 
              
              private void undoMove() 
              { 
                      if(btnUndo.isEnabled() && currMove > 0) 
                      { 
                              currMove--; 
                              movePiece(moves[currMove][3], moves[currMove][4], moves[currMove][5], moves[currMove][0], moves[currMove][1], moves[currMove][2], true); 
                      } 
              } 
              
              private void resetBoard() 
              { 
                      currMove = 0; 
                      pieceName.clear(); 
                      pieceName.put("bRook", "Black Rook"); 
                      pieceName.put("bQueen", "Black Queen"); 
                      pieceName.put("bPawn", "Black Pawn"); 
                      pieceName.put("bKnight", "Black Knight"); 
                      pieceName.put("bBishop", "Black Bishop"); 
                      pieceName.put("bKing", "Black King"); 
                      pieceName.put("wRook", "White Rook"); 
                      pieceName.put("wQueen", "White Queen"); 
                      pieceName.put("wPawn", "White Pawn"); 
                      pieceName.put("wKnight", "White Knight"); 
                      pieceName.put("wBishop", "White Bishop"); 
                      pieceName.put("wKing", "White King"); 
                      pieceName.put("wRook", "White Rook"); 
                      
                      // If we're holding a piece, clear the hover of the cell 
                      if(heldI >= 0 && heldX >= 0) 
                      { 
                              ClearHlight(heldI, heldX); 
                      } 
                      
                      switchPlayer(); 
                      
                      heldX = heldY = heldI = -1; 
              } 
              
              private void buildBoard() 
              { 
                      // First reset the variables, maps, etc. 
                      resetBoard(); 
                      
                      int rowColor = 0; 
                      int i = 0; 
                      for(int x = 0; x <= 7; x++) 
                      { 
                              rowColor++; 
                              for(int y = 0; y <= 7; y++) 
                              { 
                                      lblCells[i] = new JLabel("", JLabel.CENTER); 
                                      lblCells[i].setOpaque(true); 
                                      if(rowColor % 2 == 0) 
                                      { 
                                              lblCells[i].setBackground(Color.GRAY); 
                                      } 
                                      else 
                                      { 
                                              lblCells[i].setBackground(Color.WHITE); 
                                      } 
                                      
                                      final int passX = x; 
                                      final int passY = y; 
                                      final int passI = i; 
        
                                      lblCells[i].addMouseListener(new java.awt.event.MouseAdapter() { 
                                              public void mouseEntered(java.awt.event.MouseEvent e) { 
                                                      // If we're holding a piece show that along with the cell we're hovering 
                                                      if(heldI > 0) 
                                                      { 
                                                              lblStatus.setText("Picked up " + pieceName.get(jPieces[heldX][heldY]) + " at " + showBoardRelative(heldX, heldY) + " | Hovering: " + showBoardRelative(passX, passY)); 
                                                      } 
                                                      else // Just show what we're hovering 
                                                      { 
                                                              lblStatus.setText("Hovering: " + showBoardRelative(passX, passY)); 
                                                      } 
                                                      // Unless we hover the one we're holding... 
                                                      if(passI != heldI) 
                                                      { 
                                                              lblCells[passI].setBackground(Color.DARK_GRAY); 
                                                      } 
                                              } 
                                      }); 
                                      
                                      lblCells[i].addMouseListener(new java.awt.event.MouseAdapter() { 
                                              public void mouseExited(java.awt.event.MouseEvent e) { 
                                                      lblStatus.setText(""); 
                                                      // Unless we hover the one we're holding... 
                                                      if(passI != heldI) 
                                                      { 
                                                              // Clear the hover effect 
                                                              ClearHlight(passI, passX); 
                                                      } 
                                              } 
                                      }); 
                                      
                                      lblCells[i].addMouseListener(new java.awt.event.MouseAdapter() { 
                                              public void mouseReleased(java.awt.event.MouseEvent e) { 
                                                      if(e.getModifiers() == InputEvent.BUTTON3_MASK) 
                                                      { 
                                                              showCellInfo(passX, passY, passI); 
                                                      } 
                                                      else if(e.getModifiers() == InputEvent.BUTTON1_MASK) 
                                                      { 
                                                              clickCell(e, passX, passY, passI); 
                                                      } 
                                              } 
                                      }); 
        
                                      jPanel.add(lblCells[i]); 
                                      rowColor++; 
                                      i++; 
                              } 
                      } 
                      resetPieces(); 
              } 
              
              // Translates grid relative coordinates to chess board relative 
              // For ex.: 0x0 to 8A 
              private String showBoardRelative(int x, int y) 
              { 
                      String chessCoord = ""; 
                      chessCoord = (x - 8) * -1 + "" + (char)(y + 65); 
                      return chessCoord; 
              } 
              
              private void showCellInfo(int x, int y, int i) 
              { 
                      if(jPieces[x][y] != null && !jPieces[x][y].equals("")) 
                      { 
                              JOptionPane.showMessageDialog( null, pieceName.get(jPieces[x][y]) + " located at " + showBoardRelative(x, y), "Cell Information", JOptionPane.INFORMATION_MESSAGE ); 
                      } 
                      else 
                      { 
                              JOptionPane.showMessageDialog( null, "No piece located at " + showBoardRelative(x, y), "Cell Information", JOptionPane.INFORMATION_MESSAGE ); 
                      } 
              } 
              
              private boolean isValidMove(int fromX, int fromY) 
              { 
                      if(jPieces[fromX][fromY].length() > 0 && jPieces[fromX][fromY].charAt(0) == currPlayer) 
                      { 
                              return true;                    
                      } 
                      else 
                      { 
                              return false; 
                      } 
              } 
              
              private void movePiece(int fromX, int fromY, int fromI, int toX, int toY, int toI, boolean isUndo) 
              { 
                      if(fromX == toX && fromY == toY) 
                      { 
                              ClearHlight(fromI, fromX); 
                              lblStatus.setText("Move canceled."); 
                      } 
                      else if(isValidMove(fromX, fromY) || isUndo == true) 
                      { 
                              PaintPiece(jPieces[fromX][fromY], toI); 
                              PaintPiece("", fromI); 
                              ClearHlight(fromI, fromX); 
                              lblStatus.setText("Moved " + pieceName.get(jPieces[fromX][fromY]) + " from " + showBoardRelative(fromX, fromY) + " to " + showBoardRelative(toX, toY)); 
                              jPieces[toX][toY] = jPieces[fromX][fromY]; 
                              jPieces[fromX][fromY] = ""; 
                              if(currMove > 9) 
                              { 
                                      pushbackUndos(); 
                              } 
                              moves[currMove] = new int[6]; 
                              moves[currMove][0] = fromX; 
                              moves[currMove][1] = fromY; 
                              moves[currMove][2] = fromI; 
                              moves[currMove][3] = toX; 
                              moves[currMove][4] = toY; 
                              moves[currMove][5] = toI; 
                              movedPieces[currMove] = jPieces[fromX][fromY]; 
                              btnUndo.setEnabled(true); 
                              if(isUndo == false) 
                              { 
                                      currMove++; 
                              } 
                              switchPlayer(); 
                      } 
                      else 
                      { 
                              ClearHlight(fromI, fromX); 
                              JOptionPane.showMessageDialog( null, "It's the " + lblCurrPlayer.getText(), "Illegal Move", JOptionPane.INFORMATION_MESSAGE ); 
                      } 
              } 
              
              private void pushbackUndos() 
              { 
                      for(int i = 0; i < 9; i++) 
                      { 
                              moves[i] = moves[i + 1]; 
                              movedPieces[i] = movedPieces[i + 1]; 
                      } 
                      currMove--; 
              } 
              
              private void switchPlayer() 
              { 
                      //System.out.write(currPlayer); 
                      if(currPlayer == 'w') 
                      { 
                              currPlayer = 'b'; 
                              lblCurrPlayer.setText("Black Player's Turn."); 
                              lblCurrPlayer.setBackground(Color.BLACK); 
                              lblCurrPlayer.setForeground(Color.WHITE); 
                      } 
                      else if(currPlayer == 'b' || currPlayer == ' ') 
                      { 
                              currPlayer = 'w'; 
                              lblCurrPlayer.setText("White Player's Turn."); 
                              lblCurrPlayer.setBackground(Color.WHITE); 
                              lblCurrPlayer.setForeground(Color.BLACK); 
                      } 
              } 
        
              private void clickCell(java.awt.event.MouseEvent e, int x, int y, int i) 
              { 
                      JLabel lblClicked = (JLabel)e.getSource(); 
                      if(heldI != -1) // We're dropping a piece 
                      { 
                              jContentPane.setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR)); 
                              movePiece(heldX, heldY, heldI, x, y, i, false); 
                              heldX = heldY = heldI = -1; 
                      } 
                      else // We're picking up a piece 
                      { 
                              if(jPieces[x][y] == null || jPieces[x][y].equals("")) 
                              { 
                                      lblStatus.setText("No piece to pick up."); 
                              } 
                              else 
                              { 
                                      jContentPane.setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR)); 
                                      lblClicked.setBackground(new Color(255, 176, 70)); 
                                      lblStatus.setText("Picked up " + pieceName.get(jPieces[x][y]) + " from " + showBoardRelative(x, y)); 
                                      heldX = x; 
                                      heldY = y; 
                                      heldI = i; 
                              } 
                      } 
              } 
        
              /** 
               * This method initializes tlbMain      
               *       
               * @return javax.swing.JToolBar 
               */ 
              private JToolBar getTlbMain() { 
                      if (tlbMain == null) { 
                              lblCurrPlayer = new JLabel(); 
                              lblCurrPlayer.setText(""); 
                              lblCurrPlayer.setOpaque(true); 
                              lblStatus = new JLabel(); 
                              lblStatus.setText(""); 
                              lblStatus.setPreferredSize(new Dimension(200, 16)); 
                              lblStatus.setSize(new Dimension(200, 16)); 
                              tlbMain = new JToolBar(); 
                              tlbMain.setOrientation(JToolBar.HORIZONTAL); 
                              tlbMain.setComponentOrientation(ComponentOrientation.LEFT_TO_RIGHT); 
                              tlbMain.setFloatable(false); 
                              tlbMain.add(getBtnNewGame()); 
                              tlbMain.add(new JToolBar.Separator()); 
                              tlbMain.add(getBtnUndo()); 
                              tlbMain.add(new JToolBar.Separator()); 
                              tlbMain.add(lblCurrPlayer); 
                              tlbMain.add(new JToolBar.Separator()); 
                              tlbMain.add(lblStatus); 
                      } 
                      return tlbMain; 
              } 
        
              /** 
               * This method initializes btnNewGame    
               *       
               * @return javax.swing.JButton 
               */ 
              private JButton getBtnNewGame() { 
                      if (btnNewGame == null) { 
                              btnNewGame = new JButton(); 
                              btnNewGame.setText("New Game"); 
                              btnNewGame.addMouseListener(new java.awt.event.MouseAdapter() { 
                                      public void mouseReleased(java.awt.event.MouseEvent e) { 
                                              if(JOptionPane.YES_OPTION == JOptionPane.showConfirmDialog(null, "Are you sure you wish to end this game?")) 
                                              { 
                                                      newGame(); 
                                              } 
                                      } 
                              }); 
                      } 
                      return btnNewGame; 
              } 
        
      } 
   
  

Exception in thread "main" java.lang.IllegalArgumentException: input == null! 
      at javax.imageio.ImageIO.read(ImageIO.java:1348) 
      at newsatranc.NewSatranc.PaintPiece(NewSatranc.java:200) 
      at newsatranc.NewSatranc.RepaintPieces(NewSatranc.java:225) 
      at newsatranc.NewSatranc.resetPieces(NewSatranc.java:190) 
      at newsatranc.NewSatranc.buildBoard(NewSatranc.java:362) 
      at newsatranc.NewSatranc.<init>(NewSatranc.java:76) 
      at newsatranc.NewSatranc.main(NewSatranc.java:99)