public String toString() {

	String retStr = "-----------------\n";
	for (int i = 0; i < _board.length; i++ ) {
	    
	    if (i != 0) {
		retStr += "\n";
	    }
	    for ( int n = 0; n < _board[i].length; n ++ ) {
		retStr += "|";
		if (_board[i][n] == 1) {
		    retStr += "x";
		}
		else if (_board[i][n] == 2) {
		    retStr += "o";
		}
		else {
		    retStr += "_";
		}
	    }
	    retStr += "|";
	}
	retStr += "\n 1 2 3 4 5 6 7 ";
	retStr += "\n-----------------";
	return retStr;
    }