Error in travercing of solutions in a loop

[Aigul]

Hello! If it doesn't take much time, could you look at an error in my program?
I've made a program, that solves sudoku puzzles. It solves correct. But the program raises an error when I try to traverse solutions in a loop (sudoku can have many solutions). Looks like the error is raised in line:

for (int i=1; i<=search.getSolutionListener().solutionsNo(); i++){ ...

If the puzzle has only one solution, then there is no errors.
If it's interesting, I used the method of solving sudoku from this site: http://www.ma.utexas.edu/users/cwhite/sudoku.html

The full souce code:

import org.jacop.constraints.Constraint;
import org.jacop.constraints.SumInt;
import org.jacop.core.IntVar;
import org.jacop.core.Store;
import org.jacop.search.*;
import java.util.ArrayList;

public class Sudoku {
    public static void main(String[] args) {
        int[][] p = {
                {6, 0, 0, 0, 0, 0, 0, 1, 0},
                {0, 0, 0, 0, 0, 2, 0, 0, 3},
                {0, 0, 0, 4, 0, 0, 0, 0, 0},
                {0, 0, 0, 8, 4, 7, 5, 0, 0},
                {4, 0, 1, 0, 2, 6, 0, 0, 0},
                {0, 0, 7, 1, 3, 9, 0, 0, 0},
                {0, 5, 0, 0, 0, 0, 2, 0, 0},
                {0, 0, 0, 0, 8, 0, 0, 4, 0},
                {2, 3, 0, 9, 1, 0, 0, 0, 0},
        };

        Store store = new Store();
        IntVar One = new IntVar(store, 1, 1);
        ArrayList<Constraint> ctrArr = new ArrayList<Constraint>();
        IntVar[][][] M = new IntVar[10][9][9];
        for (int n = 1; n < 10; n++)
            for (int i = 0; i < 9; i++)
                for (int j = 0; j < 9; j++) {
                    if (p[i][j] == n)
                        M[n][i][j] = new IntVar(store, 1, 1);
                    else
                        M[n][i][j] = new IntVar(store, 0, 1);
                }
        for (int n = 1; n < 10; n++)
            for (int i = 0; i < 9; i++)
                ctrArr.add(new SumInt(store, M[n][i], "==", One));
        for (int n = 1; n < 10; n++)
            for (int j = 0; j < 9; j++) {
                IntVar[] v = new IntVar[9];
                for (int i = 0; i < 9; i++)
                    v[i] = M[n][i][j];
                ctrArr.add(new SumInt(store, v, "==", One));
            }
        for (int i = 0; i < 9; i++)
            for (int j = 0; j < 9; j++) {
                IntVar[] v = new IntVar[9];
                for (int n = 1; n < 10; n++)
                    v[n - 1] = M[n][i][j];
                ctrArr.add(new SumInt(store, v, "==", One));
            }

        for (int n = 1; n < 10; n++)
            for (int boxI = 0; boxI < 3; boxI++)
                for (int boxJ = 0; boxJ < 3; boxJ++) {
                    IntVar[] v = new IntVar[9];
                    for (int i = 0; i < 3; i++)
                        for (int j = 0; j < 3; j++)
                            v[i*3+j] = M[n][boxI*3+i][boxJ*3+j];
                    ctrArr.add(new SumInt(store, v, "==", One));
                }

        IntVar[] SolutionVector = new IntVar[9*9*9];
        for (int n = 1; n < 10; n++)
            for (int i = 0; i < 9; i++)
                for (int j = 0; j < 9; j++)
                    SolutionVector[(n-1)*9*9 + i*9 +j] = M[n][i][j];

        for (Constraint ctr: ctrArr)
            store.impose(ctr);
        DepthFirstSearch<IntVar> search = new DepthFirstSearch<IntVar>();
        search.setSolutionListener(new PrintOutListener<IntVar>());
        search.getSolutionListener().searchAll(true);
        SelectChoicePoint<IntVar> select =
                new RandomSelect<IntVar>(SolutionVector, new IndomainMin<IntVar>());
        search.labeling(store, select);
        for (int i=1; i<=search.getSolutionListener().solutionsNo(); i++){
            System.out.print("Solution " + i + ": ");
            for (int j=5; j<search.getSolution(i).length; j++) {
                if (search.getSolution(i)[j].toString().equals("1"))
                {
                    int col = j % 9;
                    int row = ((j - col) / 9)%9;
                    int num = ((j - col - row * 9) / 9) /9 +1;
                    p[row][col] = num;
                }
            }
            for (int r = 0; r < 9; r++) {
                System.out.println();
                for (int c = 0; c < 9; c++) {
                    System.out.print(p[r][c] + " ");
                }
            }
        }
    }
}

[kris]

Add

search.getSolutionListener().recordSolutions(true);

before startting search, that is before line

    search.labeling(store, select);

Best,
/Kris

[Aigul]

Thank you! Now it works.