Incorrect validation of rows in 2D array (Java)

Question

I'm a beginner in programming and I'm making a simple game similar to Tic-Tac-Toe. We have a square game field (2D array) with random size of it's side. It may look like:

[ ] [ ] [ ]
[ ] [ ] [ ]
[ ] [ ] [ ]

Here is one of the methods to check out the matches for rows:

boolean checkHorizontal(String[][] field) {
  boolean valid = true;
  for (int i = 0; i < field.length; i++) {
    for (int j = 1; j < field[i].length; j++) {
      if (!field[i][0].equals(field[i][j]) && !field[i][0].equals("[ ]")) {
        valid = false;
      }
    }
  }
  return valid;
}

And there is a problem in it. Method works correclty for usual cases, for example, like:

[ ] [ ]  O
 X   X   X 
[ ]  O  [ ]

But if the game field is empty or the first column is empty, as following,

[ ] [ ] [ ]    [ ]  X  [ ]
[ ] [ ] [ ]    [ ]  X  [ ]
[ ] [ ] [ ]    [ ]  X  [ ]

result of checkHorizontal(String[][] field) is true, but should be false, because there are no matches in rows here, and I really don't know how to fix this.

Update. The answer of @David Choweller helped me. I altered his method a little bit, but in general it's the same thing:

boolean checkHorizontal(String[][] field) {
        boolean valid = false;
        for (int i = 0; i < field.length; i++) {
            if (field[i][0].equals("[ ]")) {
                continue;
            }
            int j;
            for (j = 1; j < field[i].length; j++) {
                if (!field[i][j].equals(field[i][0])) {
                    break;
                }
            }
            if (j == field[i].length) {
                valid = true;
            }
        }
        return valid;
    }

Answer 1

Assuming you want to return true if you find any horizontal row consisting of all Xs or all Os, and your empty field is the string "[ ]" this should work:

boolean checkHorizontal(String[][] board) {
    final String emptyCell = "[ ]";

    for (int row = 0; row < board.length; row++) {
        String firstElementInRow = board[row][0];
        if (firstElementInRow.equals(emptyCell)) {
            continue;
        }
        int column;
        for (column=1; column < board[row].length; column++) {
            if (!board[row][column].equals(firstElementInRow)) {
                break;
            }
        }
        if (column==board[row].length) {
            return true;
        }
    }
    return false;
}