2 Player TicTacToe Game

Question

I am a beginner Java programmer and I have just finished creating a simple 2 player TicTacToe game and would appreciate some feedback/advice on how to make it better.

import javax.swing.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class TicTacToe implements ActionListener {

public static int turnNum;
public static JLabel title;
public static JButton[][] buttons = new JButton[3][3];
public static JButton reset;
public static boolean xTurn = true;
public static boolean won = false;
public static int[][] grid = new int[3][3];

public static void main(String[] args) {
    // Frame
    JFrame frame = new JFrame("TicTacToe");
    frame.setSize(255, 234);
    frame.setLocationRelativeTo(null);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setResizable(false);

    // Container
    JPanel container = new JPanel();
    container.setLayout(null);
    frame.setContentPane(container);

    // Contents
    // Title
    title = new JLabel("TicTacToe");
    title.setBounds(55, 10, 70, 15);

    // Buttons    
    // Loop to create add all buttons to array and to add action listeners to all
    for (int a = 0; a < buttons.length; a++) {
        for (int b = 0; b < buttons.length; b++) {
            buttons[a][b] = new JButton("_");
            buttons[a][b].addActionListener(new TicTacToe());
        }
    }
    // Row 1
    buttons[0][0].setBounds(5, 40, 50, 50);
    buttons[0][1].setBounds(60, 40, 50, 50);
    buttons[0][2].setBounds(115, 40, 50, 50);
    // Row 2
    buttons[1][0].setBounds(5, 95, 50, 50);
    buttons[1][1].setBounds(60, 95, 50, 50);
    buttons[1][2].setBounds(115, 95, 50, 50);
    // Row 3
    buttons[2][0].setBounds(5, 150, 50, 50);
    buttons[2][1].setBounds(60, 150, 50, 50);
    buttons[2][2].setBounds(115, 150, 50, 50);

    reset = new JButton("Reset");
    reset.setBounds(170, 55, 75, 20);
    reset.addActionListener(new TicTacToe());

    // Adding contents
    container.add(title);
    for (int a = 0; a < buttons.length; a++) {
        for (int b = 0; b < buttons.length; b++) {
            container.add(buttons[a][b]);
        }
    }
    container.add(reset);

    // Extras
    frame.toFront();
    frame.setVisible(true);
}

public void actionPerformed(ActionEvent event) {
    // Increase turn # by one
    turnNum++;
    // Nested loops to perform actions on any button
    for (int x = 0; x < buttons.length; x++) {
        for (int y = 0; y < buttons.length; y++) {
            if (event.getSource() == buttons[x][y]) {
                if (xTurn == true) {
                    buttons[x][y].setText("X");
                    xTurn = false;
                    buttons[x][y].setEnabled(false);
                    grid[x][y] = 1;
                } else if (xTurn == false) {
                    buttons[x][y].setText("O");
                    xTurn = true;
                    buttons[x][y].setEnabled(false);
                    grid[x][y] = 2;
                }
            }
        }
    }
    // Button event for resetting the board
    if ((event.getSource() == reset)) {
        // Set turn # back to 0
        turnNum = 0;
        // Set title back to default
        title.setText("TicTacToe");
        // Reset array
        grid = new int[3][3];
        // Set first turn to X as usual
        xTurn = true;
        // Simple loop to change buttons text to default and enable all buttons
        for (int a = 0; a < buttons.length; a++) {
            for (int b = 0; b < buttons.length; b++) {
                buttons[a][b].setEnabled(true);
                buttons[a][b].setText("_");
            }
        }
        // Make won false
        won = false;
    } else // Check if a player has won, if not, display cat's game
    if (turnNum == 9) {
        title.setText("Cat's game!");
    } else {
        hasWon(grid);
    }
}

// Method to check if a player has won
public static boolean hasWon(int[][] grid) {
    for (int a = 1; a <= 2; a++) {
        for (int b = 0; b < grid.length; b++) {
            // Checking for win in horizontal, then vertical, then diagonal
            if (grid[b][0] == a && grid[b][1] == a && grid[b][2] == a) {
                won = true;
            } else if (grid[0][b] == a && grid[1][b] == a && grid[2][b] == a) {
                won = true;
            } else if ((grid[0][0] == a && grid[1][1] == a && grid[2][2] == a
                    || (grid[0][2] == a && grid[1][1] == a && grid[2][0] == a))) {
                won = true;
            }
        }
        // If the player won, display text, disable buttons, and return true
        if (won) {
            if (a == 1) {
                // Simple loop to disable all buttons
                for (int j = 0; j < buttons.length; j++) {
                    for (int k = 0; k < buttons.length; k++) {
                        buttons[j][k].setEnabled(false);
                    }
                }
                title.setText("X has won!");
                return true;
            } else {
                for (int j = 0; j < buttons.length; j++) {
                    for (int k = 0; k < buttons.length; k++) {
                        buttons[j][k].setEnabled(false);
                    }
                }
                title.setText("O has won!");
                return true;
            }
        }
    }
    // Return false if nobody has won
    return false;
}
}

Answer 1

OOP

Use different (or the same) classes. Put everything in a class and replace your new TicTacToe(); with this. Java is not for functional programming

Buttons

Your buttons[x][y].setBound(...) can be integrated in the loop, as well as container.add(buttons[a][b]);

container.add(title);
for (int a = 0; a < buttons.length; a++) {
  for (int b = 0; b < buttons.length; b++) { 
    buttons[a][b] = new JButton("_"); 
    buttons[a][b].addActionListener(this);
    buttons[a][b].setBounds(5+(a*55),40+(55*b), 50, 50);
    container.add(buttons[a][b]);
  } 
}

actionPerformed

public void actionPerformed(ActionEvent e){
  if(e.getSource==reset){
    //do reset stuff
    return;
  }
  if(xTurn){
    e.getSource().setTitle("X");
    e.getSource().setEnabled(false);
    xTurn=false;
  }else{
    //same with "O"
  }
  turnNum++;
}

I replaces your grid with the buttons. If you want to look up who owns which fields use buttons[a][b].getTitle().equals("X"/"O").

hasWon

If you use the use the buttons to check who owns which fields I recommend do an extra method to check per letter if this letter hasWon()

public boolean hasWon(String letter){
  for(int i=0;i<buttons.length;i++){
    if(buttons[i][0].getTitle().equals(letter)&&buttons[i][1].getTitle().equals(letter)&&buttons[i][2].getTitle().equals(letter))return true;
    if(buttons[0][i].getTitle().equals(letter)&&buttons[1][i].getTitle().equals(letter)&&buttons[2][i].getTitle().equals(letter))return true;
  }
  if(buttons[0][0].getTitle().equals(letter)&&buttons[1][1].getTitle().equals(letter)&&buttons[2][2].getTitle().equals(letter))return true;
  if(buttons[0][2].getTitle().equals(letter)&&buttons[1][1].getTitle().equals(letter)&&buttons[2][0].getTitle().equals(letter))return true;
  return false;
}
public boolean hasWon(){
  if(hasWon("X")){
    //X has Won
  }else if(hasWon("O")){
    //O has Won
  }else{
    return false;
  }
  return true;
}

Still TicTacToe#hasWon(String) is massive, but I don't know how to do this smarter. :(