Solving the regions in sudoku code

Question

was able to solve the repetition of the rows and columns... but i am now having trouble solving for the regions... My professor prefers we do it in a single class with multiple methods... here is what I have..
This is my main method:
public class Test extends JApplet{
    int [][] entries = new int [9][9];
    boolean filled [][] = new boolean [9][9];
    public void paint(Graphics canvas) {
        // draws the puzzle board
        SudokuPuzzel(canvas);
        //     sets the initial values
        initialValues(canvas);
        // this adds the guess
        addGuess(canvas);
    private void initialValues(Graphics canvas) {
        int puzzleLength;
        // creates the list of numbers to be used in the array
        List numberList = new ArrayList(8);
        for (int i = 1; i<10; i++)
            numberList.add(new Integer(i));
        // this will set the initial values into the entries array
        for (int x = 0; x<9;x++)
            puzzleLength = x;
            Collections.shuffle(numberList);
            for (int y = 0; y<9; y++){
                entries[x][y] = (Integer) numberList.get(y);
            // this will check for repeats in the columns
                boolean validityColumn, validityRegion;
            do{
                validityColumn = true;
                validityRegion = true;
                validityColumn = checkColumn(puzzleLength, x);
                validityRegion = checkRegion(puzzleLength);
                if (!validityColumn || !validityRegion){
                    for (x = 1; x<3; x++)
                        Collections.shuffle(numberList);
                        for (int i =0; i<9;i++)
                            entries[x] = (Integer) numberList.get(i);
System.out.println("re-determine");
}while(!validityColumn || !validityRegion);
for (int z = 0; z<9; z++)
String value;
for(int w = 0; w<9; w++){
value = Integer.toString(entries[z][w]);
printValue(canvas, value, z, w);
This is the method that checks if the numbers in the columns are duplicatedprivate boolean checkColumn(int puzzleLength, int x) {
// this method receives the puzzle length and row
// it then checks to see if any number repeats
// in the previous rows. if so, the row is
// shuffled and realigned
for (int j = 0; j<= puzzleLength; j++){
for (int i =0; i< 9; i++)
and this checks the regions..private boolean checkRegion(int puzzleLength) {
if (puzzleLength == 2)
for (int i = 0; i<3; i++)
for (int j = 0; j<3; j++)
for (int k = 0; k <3; k++)
for (int l = 0; l<3; l++)
if ((i != k && k != l) && entries[i][j] == entries[k][l])
return false;
return true;
I am getting an infinate loop and I don't understand where or why...

Answer 1

onorinbejasus wrote:
I am getting an infinate loop and I don't understand where or why... Debug your application by placing some System.out.println's in your code and printing out the variables. That way, you see how they change and you can then deduce why an infinite loop is occurring.
Start by debugging in your do-while statement: that is the only place (from the code you posted) where it can go in an infinite loop.
I also recommend you create some "helper methods" to make the checking of rows, columns and regions easier:
boolean[] getRow(int rowNumber) {
  // For example, if the 'rowNumber' has the numbers 1, 2, 3 and 8 filled in, return the
  // following array: [true, true, true, false, false, false, false, true, false]
  // You can also choose to return the numbers [1, 2, 3, 8] of course, that;'s for you to
  // decide (the return type should be changed to int[] of course)
boolean[] getColumn(int columnNumber) {
  // the same as in getRow(...) but then the column values are returned
boolean[] getRegion(int regionNumber) {
}Good luck.