Thread: first consul game in java (tic tace): problem with the winner check method

Exception in thread "main" java.lang.NullPointerException
at starting.Lerning_Arrays.winnerCheker(Lerning_Array s.java:78)

Look at the statement at line 78 and try to find the variable with the null value. Then backtrack in the code to see why that variable does not have a valid value.

Originally Posted by Norm

Look at the statement at line 78 and try to find the variable with the null value. Then backtrack in the code to see why that variable does not have a valid value.

Hey,
I have checked and I initialize the variable that was null this problem is solved/

it's still doesn't find the winner the func is now working

This is the problematic function:

static String winnerCheker() {
		String answer = "";
		for(int a = 0 ; a < 8 ; a++) {
			String line = "";
			switch (a) {
				case 0:
					line = board[0][0] + board[0][1] + board[0][2];
					break;
				case 1:
					line = board[1][0] + board[1][1] + board[1][2];
					break;
				case 2:
					line = board[2][0] + board[2][1] + board[2][2];
					break;
				case 3:
					line = board[0][0] + board[1][0] + board[2][0];
					break;
				case 4:
					line = board[0][1] + board[1][1] + board[1][2];
					break;
				case 5:
					line = board[1][2] + board[0][2] + board[2][2];
					break;
				case 6:
					line = board[0][0] + board[1][1] + board[2][2];
					break;
				case 7:
					line = board[0][2] + board[1][1] + board[2][0];
					break;
			}
			if (line.equals("XXX")) {
				answer = line;
			} else if (line.equals("OOO")) {
				answer = line;
			}	
		}
		return answer;
	}

What is the statement on line 78 where the exception happened?
What variable on that line has the null value?
What statement gave a value to that variable?

Originally Posted by Norm

What is the statement on line 78 where the exception happened?
What variable on that line has the null value?
What statement gave value to that variable?

78: line = board[0][0] + board[0][1] + board[0][2];
all variable as initialized

static String line = "1"; //I initialized its with 1 just for its no to be null
public static String[][] board; // this is the main array for the game

	static String winnerCheker() {
		for(int a = 0 ; a < 8 ; a++) {
			switch (a) {
				case 0:
					line = board[0][0] + board[0][1] + board[0][2];
					break;
				case 1:
					line = board[1][0] + board[1][1] + board[1][2];
					break;
				case 2:
					line = board[2][0] + board[2][1] + board[2][2];
					break;
				case 3:
					line = board[0][0] + board[1][0] + board[2][0];
					break;
				case 4:
					line = board[0][1] + board[1][1] + board[1][2];
					break;
				case 5:
					line = board[1][2] + board[0][2] + board[2][2];
					break;
				case 6:
					line = board[0][0] + board[1][1] + board[2][2];
					break;
				case 7:
					line = board[0][2] + board[1][1] + board[2][0];
					break;
			}
			if (line.equals("XXX")) {
				return line;
			} else if (line.equals("OOO")) {
				return line;
			}	
		}
		return line;
	}

Thank you!!!

Sorry, I still do not understand what variable has the null value.
Can you give the name of the variable with the null value?

If you can not tell which variable has the null value, add a print statement just before line 78 that prints the values of the variables on line 78.

78: line = board[0][0] + board[0][1] + board[0][2];

What values are in board[0][0] and board[0][1] and board[0][2]?

Where is the variable: board assigned a value?