HELP!! Code won't compile - NullPointerException

[JuliaDavies]

Hi, I am making a sudoku problem solver and I have tried to make a GUI interface, but now it won't compile and gives the error mesage:
Exception in thread "main" java.lang.NullPointerException
at java.awt.Container.addImpl(Container.java:1045)
at java.awt.Container.add(Container.java:365)
at Sudoku.SwingSudokuBoard.<init>(SwingSudokuBoard.ja va:34)
at Sudoku.SwingSudokuBoard.<init>(SwingSudokuBoard.ja va:126)
at Sudoku.SudokuMainClass.main(SudokuMainClass.java:2 8)

CODE:
package Sudoku;

public class SudokuMainClass {

public static void main(String[] args) {
int[][] board = {{0, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0}};
new SwingSudokuImplement(new SwingSudokuBoard(board));;
}
}
///////
package Sudoku;

public class SudokuImplement {
private SudokuBoard sb; // Puzzle to solve

public SudokuImplement(SudokuBoard sb) {
this.sb = sb;
}

private boolean check(int num, int row, int col) {
int r = (row / sb.box_size) * sb.box_size;
int c = (col / sb.box_size) * sb.box_size;

for (int i = 0; i < sb.size; i++) {
if (sb.getCell(row, i) == num ||
sb.getCell(i, col) == num ||
sb.getCell(r + (i % sb.box_size), c + (i / sb.box_size)) == num) {
return false;
}
}
return true;
}

public boolean test(int row, int col) {
int nextCol = (col + 1) % sb.size;
int nextRow = (nextCol == 0) ? row + 1 : row;

try {
if (sb.getCell(row, col) != sb.EMPTY)
return test(nextRow, nextCol);
}
catch (ArrayIndexOutOfBoundsException e) {
return true;
}

for (int i = 1; i <= sb.size; i++) {
if (check(i, row, col)) {
sb.setCell(i, row, col);
if (test(nextRow, nextCol)) {
return true;
}
}
}
sb.setCell(sb.EMPTY, row, col);
return false;
}
}
////////
package Sudoku;

public class SudokuBoard {
final int EMPTY = 0; // marks empty cell
final int size; // board size
final int box_size; // 3x3 cell size

private int[][] board; // 2D array of the board

public SudokuBoard(int size) {
board = new int[size][size];
this.size = size;
this.box_size = (int) Math.sqrt(size);
}

public SudokuBoard(int[][] board) {
this(board.length);
this.board = board;
}

public void setCell(int num, int row, int col) {
board[row][col] = num;
}

public int getCell(int row, int col) {
return board[row][col];
}
}
////////
package Sudoku;

import java.awt.*;
import javax.swing.*;

public class SwingSudokuImplement extends javax.swing.JFrame {

private final SudokuImplement imp;
public SudokuImplement ip(){return imp;}

@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {

textField0a = new java.awt.TextField();
textField1a = new java.awt.TextField();
textField9a = new java.awt.TextField();
textField18a = new java.awt.TextField();
textField10a = new java.awt.TextField();
textField2a = new java.awt.TextField();
textField11a = new java.awt.TextField();
textField19a = new java.awt.TextField();
textField20a = new java.awt.TextField();
textField3a = new java.awt.TextField();
textField4a = new java.awt.TextField();
textField12a = new java.awt.TextField();
textField23a = new java.awt.TextField();
textField22a = new java.awt.TextField();
textField13a = new java.awt.TextField();
textField21a = new java.awt.TextField();
textField14a = new java.awt.TextField();
textField5a = new java.awt.TextField();
textField6a = new java.awt.TextField();
textField7a = new java.awt.TextField();
textField15a = new java.awt.TextField();
textField26a = new java.awt.TextField();
textField25a = new java.awt.TextField();
textField16a = new java.awt.TextField();
textField24a = new java.awt.TextField();
textField17a = new java.awt.TextField();
textField8a = new java.awt.TextField();
button1 = new java.awt.Button();
button2 = new java.awt.Button();
textField42a = new java.awt.TextField();
textField52a = new java.awt.TextField();
textField53a = new java.awt.TextField();
textField51a = new java.awt.TextField();
textField43a = new java.awt.TextField();
textField44a = new java.awt.TextField();
textField35a = new java.awt.TextField();
textField50a = new java.awt.TextField();
textField49a = new java.awt.TextField();
textField31a = new java.awt.TextField();
textField39a = new java.awt.TextField();
textField34a = new java.awt.TextField();
textField33a = new java.awt.TextField();
textField32a = new java.awt.TextField();
textField41a = new java.awt.TextField();
textField48a = new java.awt.TextField();
textField40a = new java.awt.TextField();
textField27a = new java.awt.TextField();
textField28a = new java.awt.TextField();
textField36a = new java.awt.TextField();
textField47a = new java.awt.TextField();
textField46a = new java.awt.TextField();
textField30a = new java.awt.TextField();
textField37a = new java.awt.TextField();
textField45a = new java.awt.TextField();
textField38a = new java.awt.TextField();
textField29a = new java.awt.TextField();
textField69a = new java.awt.TextField();
textField79a = new java.awt.TextField();
textField80a = new java.awt.TextField();
textField78a = new java.awt.TextField();
textField70a = new java.awt.TextField();
textField71a = new java.awt.TextField();
textField62a = new java.awt.TextField();
textField77a = new java.awt.TextField();
textField76a = new java.awt.TextField();
textField58a = new java.awt.TextField();
textField66a = new java.awt.TextField();
textField61a = new java.awt.TextField();
textField60a = new java.awt.TextField();
textField59a = new java.awt.TextField();
textField68a = new java.awt.TextField();
textField75a = new java.awt.TextField();
textField67a = new java.awt.TextField();
textField54a = new java.awt.TextField();
textField55a = new java.awt.TextField();
textField63a = new java.awt.TextField();
textField74a = new java.awt.TextField();
textField73a = new java.awt.TextField();
textField57a = new java.awt.TextField();
textField64a = new java.awt.TextField();
textField72a = new java.awt.TextField();
textField65a = new java.awt.TextField();
textField56a = new java.awt.TextField();

setDefaultCloseOperation(javax.swing.WindowConstan ts.EXIT_ON_CLOSE);
setTitle("Sudoku Problem Sovler");

button1.setLabel("Solve");

button2.setLabel("Next Sudoku");

javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout .Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.TRAILING)
.addComponent(textField18a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField9a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField0a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField1a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField10a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField19a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField20a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField11a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField2a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.Component Placement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.TRAILING)
.addComponent(textField21a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField12a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField3a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField4a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField13a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField22a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField23a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField14a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField5a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.Component Placement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.TRAILING)
.addComponent(textField24a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField15a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField6a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField7a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField16a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField25a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField26a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField17a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField8a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.TRAILING)
.addComponent(textField45a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField36a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField27a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField28a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField37a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField46a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField47a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField38a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField29a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.Component Placement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.TRAILING)
.addComponent(textField48a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField39a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField30a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField31a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField40a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField49a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField50a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField41a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField32a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.Component Placement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.TRAILING)
.addComponent(textField51a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField42a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField33a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField34a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField43a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField52a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField53a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField44a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField35a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.TRAILING)
.addComponent(textField72a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField63a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField54a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField55a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField64a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField73a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField74a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField65a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField56a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addComponent(button1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.Component Placement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.TRAILING)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.TRAILING)
.addComponent(textField75a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField66a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField57a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField58a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField67a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField76a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField77a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField68a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField59a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.Component Placement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.TRAILING)
.addComponent(textField78a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField69a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField60a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField61a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField70a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField79a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField80a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField71a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField62a, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addComponent(button2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))))
.addContainerGap())
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout .Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField6a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField7a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField8a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField15a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField16a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField17a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField26a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField25a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField24a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField3a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField4a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField5a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField12a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField13a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField14a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField23a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField22a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField21a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField0a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField1a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField2a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField9a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField10a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField11a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField20a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField19a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField18a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))))
.addPreferredGap(javax.swing.LayoutStyle.Component Placement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField33a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField34a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField35a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField42a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField43a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField44a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField53a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField52a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField51a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField30a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField31a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField32a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField39a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField40a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField41a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField50a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField49a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField48a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField27a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField28a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField29a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField36a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField37a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField38a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField47a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField46a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField45a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))))
.addPreferredGap(javax.swing.LayoutStyle.Component Placement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField57a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField58a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField59a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField66a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField67a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField68a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField77a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField76a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField75a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField54a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField55a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField56a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField63a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField64a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField65a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField74a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField73a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField72a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField60a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField61a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField62a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField69a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField70a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField71a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(2, 2, 2)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(textField80a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField79a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(textField78a, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))))
.addGap(19, 19, 19)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.TRAILING)
.addComponent(button1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(button2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addContainerGap(javax.swing.GroupLayout.DEFAULT_S IZE, Short.MAX_VALUE))
);

pack();
}// </editor-fold>

public SwingSudokuImplement(SwingSudokuBoard ssb) {

initComponents();
imp = new SudokuImplement(ssb);
final JPanel panel = ssb.getPanel();

Runnable runner = new Runnable() {
public void run() {

}
};
EventQueue.invokeLater(runner);
}

private static void addComponent(Container container, Component component,
int gridx, int gridy, int gridwidth, int gridheight) {
Insets insets = new Insets(0, 0, 0, 0);
GridBagConstraints gbc = new GridBagConstraints(gridx, gridy, gridwidth,
gridheight, 1, 1, GridBagConstraints.CENTER,
GridBagConstraints.BOTH, insets, 0, 0);
container.add(component, gbc);
}

// Variables declaration - do not modify
variables
// End of variables declaration

}
/////////
package Sudoku;

import java.awt.*;
import javax.swing.*;

public final class SwingSudokuBoard extends SudokuBoard {

private TextField[][] cells; // Graphical game board in an array
private JPanel panel = new JPanel();

public SwingSudokuBoard(int size) {
super(size);
cells = new TextField[size][size];
panel.setLayout(new GridLayout(size, size));
for (int row = 0; row < size; row++) {
for (int col = 0; col < size; col++) {
panel.add(cells[row][col]);
}
}
cells[0][0] = textField0a;
cells[0][1] = textField1a;
cells[0][2] = textField2a;
cells[0][3] = textField3a;
//DECLARE textField4a to textField8a

}

public SwingSudokuBoard(int[][] board) {
this(board.length);
for (int row = 0; row < size; row++) {
for (int col = 0; col < size; col++) {
setCell(board[row][col], row, col);
}
}
}

@Override
public void setCell(int num, int row, int col) {
setCell(num, row, col);
String text = (num == EMPTY) ? "" : String.valueOf(num);
cells[row][col].setText(text);
}

@Override
public int getCell(int row, int col) {
int cell;

try {
cell = Integer.parseInt(cells[row][col].getText());
}
catch (NumberFormatException e) {
cell = EMPTY;
}
return cell;
}

public JPanel getPanel() {
return panel;
}

// Variables declaration - do not modify
variables
// End of variables declaration
}
Thank you!!

[Tolls]

Pleas use [code] tags [/code] when posting code.
That is unreadable without them.

On top of that, that is far too much code to follow anyway.
And you also don't show us which line of code is throwing the NullPointer.

[JuliaDavies]

I really would have made it a lot simpler if I knew how :( sorry :(
The code that's throwing the null pointer is (SwingSudokuBoard - public SwingSudokuBoard(int size)) panel.add(cells[row][col]); and (SwingSudokuBoard - public SwingSudokuBoard(int[][] board)) this(board.length);
Thank you

[Tolls]

So, all I can say is something on that line is null, either 'panel' or 'cells'.
You really will have to use code tags if you want someone to do more than a cursory look at this.

[DarrylBurke]

Don't double post. Your other thread has been closed.

NullPointerException is a runtime exception. You can't run code that doesn't compile. Make up your mind: what's your problem, that the code doesn't compile or that it compiles but throws a NPE when run?

The stack trace implies that the component you're trying to add to the container at line 34 in the constructor of Sudoku.SwingSudokuBoard has not been initialized.

If you're so new to Java that you can't trace a NPE, why on earth are you using a sophisticated tool like a visual GUI designer and code generator? When learning to drive, would you get into the cockpit of a racing car?

db

[JuliaDavies]

Look, I'm sorry, I only came on here to find some help, not to get patronised on what I should and shouldn't know about java.
I am not new to Java, I have been doing it for 3 years, however I do not know how to trace a NPE. Why does it matter? I'm asking for help.

The code does compile but throws the NullPointerException when run. There are no red lines in my code.
Is it because int size hasn't been initialised?
I just want some help, not somone to tell me that I am stupid at Java.
Thank you

[DarrylBurke]

Set a breakpoint on the line that throws the NPE and step through the code using a debugger. Check the values dereferenced on that line and find out which is/are null.

And my comment stands; anyone who hasn't yet learned the fundamentals of debugging should stay away from hard-to-decipher auto-generated code. Writing your own GUI code is tons easier than sorting out the mess created by a visual designer when something goes wrong.

It was neither stated nor implied that you are stupid at Java.

db

[DarrylBurke]

For the second time, don't double post. If you continue to flout this rule, you may face a ban.

The third thread you started for this has been closed.

db

[DarrylBurke]

And you were advised both here and in the first locked thread about using code tags, but had to be told that again in the second locked thread. Is it really so difficult to do or do you enjoy cluttering the forum with unformatted code?

db

[JuliaDavies]

Yes, I totally enjoy cluttering the forum with unformatted code :)
Thanks for closing my array index out of bounds exception thread - it was a completely different question but there you go, you obviously know best!
To anyone who cannot read code without tags - good for you! It's hardly hard to read the code like it is, since you are such a good programmer, you should know which bits aren't necessary to read and I would have thought that this would have been simple enough for most people to answer.
Thanks for everything, you have been so helpful!

[Tolls]

We follow the flow of code by the structure, which is obvious when code is formatted.
Without it we have to actually read the code to try and see how it flows.

Of course the other thing is, if you can't be arsed to help us go through your problem then why do you expect us (volunteers remember) to be arsed to help you?