Getting sudoku possible solutions Method

Question

So this is a follow up question to this one:

From given row(x),column(y), find 3x3 subarray of a 2D 9x9 array

I'm writing a method that takes the row, column combination of a 2D array, scans the rows, columns and 3x3 subarrays for possible solutions at this specific position. So far, everything looks good. The first for-loop scans the row and stores already used numbers (between 1-9) in an alreadyInUse array. The second does the same for the column. The third for-loop determines the position of the subarray using the row,column combination, searches this 3x3 subarray and stores already found numbers in same alreadyInUse array.

// Method for calculating all possibilities at specific position
public int[] getPossibilities(int row, int col){
    int [] alreadyInUse;
    int [] unsorted = new int[9];
    int currentIndex = 0;
    int size = 0;
    boolean match;
    if(sudoku[row][col] != 0){
        return  new int[]{sudoku[col][row]};
    }
    else{
        alreadyInUse = new int[26];
        //Go into Row x and store all available numbers in alreadyInUse
        for(int i=0; i<sudoku.length; i++){
            if(sudoku[row][i] !=0){
                alreadyInUse[currentIndex] = sudoku[row][i];
                currentIndex++;
            }
        }
        //Go into Column y and store all available numbers in alreadyInUse
        for(int j=0; j<sudoku.length; j++){
            if(sudoku[j][col] !=0){
                alreadyInUse[currentIndex] = sudoku[j][col];
                currentIndex++;
            }
        }
        //Go into subarray and store all available numbers in alreadyInUse
        int x_left = row - (row%3);
        int y_top = col - (col%3);
        for(int i=0; i<3; i++){
            for(int j=0; j<3; j++){
                if(sudoku[i+x_left][j+y_top] != 0){
                    alreadyInUse[currentIndex] = sudoku[i+x_left][j+y_top];
                }
            }
        }
        //compare 1-9 with the numbers stored in alreadyInUse array
        for(int i=1; i<10; i++){
            match = false;
            //if a pair matches, break;
            for(int j=0; j<alreadyInUse.length; j++){
                if(alreadyInUse[j] == i ){
                    match = true;
                    break;
                }
            }
            //If no pair matches, store the number (i) in an unsorted array
            if(!match){
                size++;
                unsorted[i-1] = i;
            }
        }
        //Re-use alreadyInUse array
        alreadyInUse = new int[size];
        size = 0;
        //Remove the zeros and store the rest of the numbers in alreadyInUse array
        for(int i=0; i<unsorted.length; i++){
            if(unsorted[i] != 0){
                alreadyInUse[size] = unsorted[i];
                size++;
            }
        }
        return alreadyInUse;    
    }   
}

When i test the output like this:

 public class SudokuTest {
 public static void main(String[] args){
    Sudoku sudoku;
    String sud = "250030901010004000407000208005200000000098100040003000000360072070000003903000604";
    sudoku = new Sudoku(sud);
    System.out.println(sudoku.getPossibilities(3,4));

I get this as an output: [I@659e0bfd even though the debug shows me that alreadyInUse array contains the correct values. Can anybody help out here?

Answer 1

You can not directly print arrays of int. You need to:

import java.util.Arrays;
...
System.out.println(Arrays.toString(sudoku.getPossibilities(3,4)));