Question

I’m scanning a text file that has a sudoku board with a few separators. this is what a sample input would look like.

1 - - | 4 5 6 | - - -  
5 7 - | 1 3 b | 6 2 4  
4 9 6 | 8 7 2 | 1 5 3  
======+=======+======  
9 - - | - - - | 4 6 -  
6 4 1 | 2 9 7 | 8 3 -  
3 8 7 | 5 6 4 | 2 9 -  
======+=======+======     
7 - - | - - - | 5 4 8   
8 r 4 | 9 1 5 | 3 7 2   
2 3 5 | 7 4 $ | 9 1 6  

where it has “|” as borders and =====+====+==== as dividers. I made this code to ignore the | and ====+===+=== but it’s skipping that part of the code and declaring them as invalid characters and adding 0’s in there place

public static int [][] createBoard(Scanner input){

    int[][] nSudokuBoard = new int[9][9];

  for (rows = 0; rows < 9; rows++){

        for (columns = 0; columns < 9; columns++){

            if(input.hasNext()){

                if(input.hasNextInt()){
                    int number = input.nextInt();
                    nSudokuBoard[rows][columns] = number;
               }//end if int

                else if(input.hasNext("-")){
                    input.next();
                    nSudokuBoard[rows][columns] = 0;
                    System.out.print("Hyphen Found \n");
                    }//end if hyphen

                else if(input.hasNext("|")){
                    System.out.print("border found \n");
                    input.next();

                }// end if border
                else if(input.hasNext("======+=======+======")){
                    System.out.print("equal row found \n");
                    input.next();
                }// end if equal row

               else {
                   System.out.print("Invalid character detected at... \n Row: " + rows +" Column: " + columns +"\n");
                   System.out.print("Invalid character(s) replaced with a '0'. \n" );
                   input.next();
               }//end else

            }//end reading file
       }//end column for loop
    }//end row for looop
 return  nSudokuBoard;
}//end of createBoard

I talked it over with a tutor but i don’t remember his suggestion on how to fix this.

Answer 1

Your loops increment the row and column counters even when you are consuming a border or a divider. So even after you fix other issues (as explained in the previous answer), you will finish filling the matrix before you’ve read all your input. You need to modify your code to conditionally advance the row and column counters only after you’ve consumed an integer or a dash. This would mean removing the for loops, changing the first if(input.hasNext()) to a while, and adding rows++ and columns++ in the places where you’ve consumed an integer or dash and are setting a value for nSudokuBoard[rows][columns]. You would also need logic to determine when to increment rows and when to set columns back to 0.

Also, stylistically speaking, you should rename rows to row and columns to column.