Trouble reading a char array in java. What am I doing wrong?

Question

I'm getting the error "Exception in thread "main" java.lang.NullPointerException" when I try to read an array value. Here is the code that I think causes the error.

        class Board
{
    private static char[][] board;

    public Board(int r, int c)
    {
        setRow(r);
        setColumn(c);
        char board[][] = new char[row][column];
    }

    public void getBoard()
    {
        for (int c = 1;c <= getColumn()-1 ;c++)
        {
            System.out.print("\t"+c);
        }
        System.out.print("\n");
        for (int r = 1; r <= getRow()-1; r++)
        {
            System.out.print(r);
            for (int c = 1; c <= getColumn(); c++)
            {
                System.out.print("\t" + board[r][c]);  //I think board[r][c] is causing it.
            }
            System.out.println("");
        }
        return;
    }
}

I can upload the whole file if need be.

Any help would be appreciated, this kept me up last night.

add a -1 to the last for loop, for (int c = 1; c <= getColumn()-1; c++) ` — Sense
– Sense, Commented Sep 26, 2012 at 14:47
Also, a "getXxx" method that doesn't return anything is misleading. You should probably call this "printBoard". — Stephen C
– Stephen C, Commented Sep 26, 2012 at 14:52

Denys Séguret · Accepted Answer · 2012-09-26 14:45:47Z

2

Replace

char board[][] = new char[row][column];

with

board = new char[row][column];

In the first statement, you're assigning a value to a local variable, not to the one of your instance.

answered Sep 26, 2012 at 14:45

Denys Séguret

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1 Comment

user1700564 Over a year ago

Thanks that did it! Saved the day.

Amit Deshpande · Accepted Answer · 2012-09-26 14:48:46Z

1

You are hiding member variable in the constructor

char board[][] = new char[row][column];

it should be

 board= new char[row][column];

answered Sep 26, 2012 at 14:48

Amit Deshpande

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