How to display tictactoe board using map and forEach?

Question

I want to display tic tac toe board. Something like that:

XXX
XXX
XXX

Is it possible to use for each to achieve that? I tried to do some:

    Map<Integer, Tile> board = generateBoard();

    for (Map.Entry<Integer, Tile> entry: board.entrySet()){
        System.out.print(entry.getValue().getSign());
    }

    board.forEach((k,v) -> {
        int i = 1;
        if(i % 3 == 0){
            System.out.println();
        }
        System.out.print(v.getSign());
        i++;
    });

But my output is incorrect. Could you give me any output to achieve me this output?

What do you mean by incorrect? Also could you please provide a [minimum, complete, verifiable, example](https://stackoverflow.com/help/mcve)? — Chris, Jun 28 '17 at 22:50
Read the code you wrote in plain English. *Set i equal to one. Test to see if one modulo three is zero, and if so call println. Call print, and then add one to i. Then go back to Set i equal to one.* Does that seem right to you? — Ken White, Jun 28 '17 at 22:53

score 1 · Answer 1 · answered Jun 28 '17 at 22:53

One obvious problem is that i isn't incremented because you're redefining it on each iteration. Unfortunately, labmdas and stateful variables don't mix well. I would suggest using a regular for loop instead:

int i = 0;
for (Tile tile : board.values()) {
    System.out.print(tile.getSign());
    if (++i % 3 == 0) {
        System.out.println();
    }
}

score 0 · Answer 2 · answered Jun 29 '17 at 00:47

0

Two things:

Your i will never increment, as it is declared within the loop. It will always be 1.
If you have "k" (the index) why are you creating a new index?

Remove i and replace it with k and see if that helps.

answered Jun 29 '17 at 00:47

UnkJester

19
3

Ryan Leach · Answer 3 · 2017-06-29T03:41:12.527

0

Variables referenced inside lambda from outside the lambda must be Effectively Final or final. This prevents you from easily incrementing a counter remembering where you are up to.

Assuming that the integer key in your map, is the slot number you can do this.

 board.forEach((k,v) -> {
        System.out.print(v.getSign());
        if(k % 3 == 0){
            System.out.println();
        }
    });

edited Jun 29 '17 at 03:41

answered Jun 29 '17 at 00:53

Ryan Leach

4,262
5
34
71

1

Variables *inside* lambdas are **not** effectively final. Variables *outside* lambdas may only be referenced *within* them if they're final or effectively final. – shmosel Jun 29 '17 at 03:28
Thanks. I've edited to make the language I used more clear. – Ryan Leach Jun 29 '17 at 03:41

How to display tictactoe board using map and forEach?

3 Answers3