TicTacToe win conditions problems

Question

New programmer here, writing a Tictactoe game using Java on Eclipse.

I have problems with my win conditions I think. It comes up with the error: Exception in thread "main" java.lang.NullPointerException at Game.NoughtsCrosses.(NoughtsCrosses.java:106) at Game.Main.main(Main.java:5)

Here is my win conditions bit. It's not well made imo, but I'm having problems when compiling. Can anyone spot why? Ty!!

I have squares set up in a 3x3 grid, 0 -> 8. Each button has its own text which is set to X or O when clicked by each player.

winconditions code:

if (square[0].getText().equals(square[1].getText()) && square[1].getText().equals(square[2].getText()) != square[0].getText().isEmpty()) {
    win = true;
}

Full Pastebin of code

Thanks again :) Any questions, I can elaborate :D

Answer 1

Well I took the code that you provided and after significant finagling was able to make a fully functioning Tic-Tac-Toe game. You were mostly on the right track with what you were doing you just needed to first begin with a design.

In my NoughtsCrosses class I have the following:

• class Action implements ActionListener
  • This has a JButton attribute that I pass in through a constructor
  • In the actionPerformed
    • set the text
    • disable the button
    • increment the counter
    • check if someone wins
      • If there is a winner or draw game ends set the "Play again?" text
      • else call the changeTurn function
• class Reset implements ActionListenter
  • This has a JButton attribute that I pass in through a constructor
  • In the actionPerformed
    • I call the resetGame function
• function changeTurn
• function resetGame
• function checkForWinners

as a hint, this is my implementation of the Action class and an example of the constructor I mentioned

class Action implements ActionListener{ 
 private JButton button;
 public Action(JButton button){ 
  this.button = button; 
 } 
 public void actionPerformed(ActionEvent e) { 
   button.setText(letter); 
   button.setEnabled(false); 
   counter++; 
   boolean gameOver = checkForWinners(); 
   if(!gameOver) 
    changeTurn(); 
   else{ 
    newgame.setText("Play again?"); 
    newgame.addActionListener(resetButton); 
   } 
 } 
}

a call like new Action(square[i]) is what you need to make this work. Note: the resetButton is of the Reset class I mention above much like the Action class it has the same construct that I passed newgame into.