Messup with 2D string array in java

Question

I just moved recently to use java and after I learn some of the syntax I decided to write a chess game to teach myself more.

I'm trying to create an array of array of string to store the basic view of the board, but when I print it out everything is null.

private String board[][] = new String[8][8];

    public Board() {
        System.out.println("created");
        for (String[] row : board) {
            for (String cell : row) {
                cell = "-";
            }
        }
        printBoard();
    }

It's feel like I'm messing a bit with the for each or the string concept.

Thanks in advance,

Or

YoungHobbit · Accepted Answer · 2015-12-25 18:38:37Z

1

cell = "-";

This assignment is happening to the local variable declared in the for loop.

You need to access each of the element in the array and assign the String.

for (int i=0; i<board.length; i++) {
    for (int j=0; j<board[i].length; j++) {
        board[i][j] = "-";
    }
}

Here board.length is the number of String[] (rows) and board[i].length and number String in each array (column).

edited Dec 25, 2015 at 18:38

answered Dec 18, 2015 at 15:28

YoungHobbit

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Comments

Mohammed Aouf Zouag · Accepted Answer · 2015-12-18 15:28:13Z

0

You should not use a forech loop to fill the array. Use a regular for loop instead. Change

for (String[] row : board) {
    for (String cell : row) {
        cell = "-";
    }
}

to

for(int i = 0; i < board.length; i++) {
    for(int j = 0; j < board[i].length; j++) {
        board[i][j] = "-";
    }
}

The foreach loop cannot modify the elements of the iterated array.

answered Dec 18, 2015 at 15:28

Mohammed Aouf Zouag

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4 Comments

Mohammed Aouf Zouag Over a year ago

If you take a closer look, you will see that using a foreach loop, you are only modifying copies, not the real thing.

Smiled_One Over a year ago

Ho...Thank. So I can use for each loop to copy and sort of staff, but not modifie the same loop?

Mohammed Aouf Zouag Over a year ago

Yes, in deed. (I think you should accept this answer instead, it's providing more details)

phflack Over a year ago

You can, however, keep your first for-each loop and use for(String[] row : board) for(int i = 0; i < row.length; i++) row[i] = "-";

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