Calling the repaint() method

I am developing a game called Tic Tac Toe. I first made a standalone application and then converted it into a JApplet.
In my game i have a button called as "New Game". Whenever a user presses this button the game is started all over again. The problem is, i have written some logic for it, but it is not working.

The problem is, i dont know wat to put in the paint method. In my case all the logic is implemented in init() and actionPerformed() method. So my paint method is empty. And when i call repaint(), it is having no effect.

Which logic should come in the paint method?

Below is the code which i have written till now.

import java.applet.*;
import java.awt.*;
import java.awt.event.*;

import javax.swing.*;

public class TicTacToe_applet extends JApplet implements ActionListener{
	
	private int[][] winCombinations = new int[][] {
			{0, 1, 2}, {3, 4, 5}, {6, 7, 8}, //horizontal wins
			{0, 3, 6}, {1, 4, 7}, {2, 5, 8}, //vertical wins
			{0, 4, 8}, {2, 4, 6}			 //diagonal wins
		};
	//private JFrame window = new JFrame("Tic-Tac-Toe");
	private JButton buttons[] = new JButton[9];
	private int count = 0;
	private String letter = "";
	private boolean win = false;
	static final Color BACKGROUND = new Color(255, 204, 204);
	JButton startButton;
	JPanel p1;
	JPanel p2;
	JPanel p3;
	JPanel p4;
	JLabel label1;
	public void actionPerformed(ActionEvent a) {
		JButton button1 = (JButton)a.getSource();
		if(button1 == startButton) {
			repaint();
			
			
		}
		
		else {
			count++;
			
			/*Calculate whose turn it is*/
			if(count % 2 == 0){
				letter = "<HTML><font color=pink>O</font></HTML>";

} else {
				letter = "<HTML><font color=blue>X</font></HTML>";

}

/*Write the letter to the button and deactivate it*/
			 JButton pressedButton = (JButton)a.getSource(); 
			 pressedButton.setBackground(BACKGROUND);
			 pressedButton.setText(letter);
			 pressedButton.setEnabled(false);
			
			/*Determine who won*/
			for(int i=0; i<=7; i++){
				if( buttons[winCombinations[i][0]].getText().equals(buttons[winCombinations[i][1]].getText()) && 
					buttons[winCombinations[i][1]].getText().equals(buttons[winCombinations[i][2]].getText()) && 
					buttons[winCombinations[i][0]].getText() != ""){
					win = true;
				}
			}
			
			/*Show a dialog when game is over*/
			if(win == true){
				JOptionPane.showMessageDialog(null, letter + " wins the game!");
				System.exit(0);
			} else if(count == 9 && win == false){
				JOptionPane.showMessageDialog(null, "The game was tie!");
				System.exit(0);
			}

}
		
			}

public void init(){
		
	    startButton = new JButton("New Game");
	    
	    p1 = new JPanel(new FlowLayout(FlowLayout.CENTER));
	    
	    p2 = new JPanel();
	    label1 = new JLabel("Games of X and O's developed by Group 6");
	    
	     
	    p3 = new JPanel(new GridLayout(3,3));
	    Container g1 = getContentPane();
		g1.setSize(300,350);
		g1.setBackground(BACKGROUND);
		p1.setBackground(BACKGROUND);
	    p1.setPreferredSize(new Dimension(300,40));
	    p1.add(startButton);
	    
	    p2.setSize(300,25);
	    p2.add(label1);
	    p2.setBackground(BACKGROUND);
	    
		
	    p3.setBackground(BACKGROUND);
	    p3.setPreferredSize(new Dimension(300,235));
		
		
		
		
		for(int i=0; i<=8; i++){
			buttons[i] = new JButton();
			p3.add(buttons[i]);
			buttons[i].addActionListener(this);
			buttons[i].setBackground(BACKGROUND);
			buttons[i].setForeground(BACKGROUND);
			//buttons[i].setBorder(BorderFactory.createEmptyBorder());
		}
		p4 = new JPanel(new FlowLayout(FlowLayout.CENTER));
		p4.setPreferredSize(new Dimension(300,350));
		p4.add(p1);
		p4.add(p2);
		p4.add(p3);
		p4.setBackground(BACKGROUND);
		g1.add(p4);
		g1.setBackground(BACKGROUND);
		//window.add(p2);
		
		/*Make The Window Visible*/
		g1.setVisible(true);

/*Add Buttons To The Window*/
		
				
	}
	
	public void paint(Graphics g){
		
	}

}

> i dont know wat to put in the paint method.

you don't need to put anything there.

the game changes/paints itself via
pressedButton.setText(letter);

so, for new game, iterate the buttons clearing the x/o's via setText("")
and you would need to reset player turn and any other variable you use in the game

To the above code, i added the following code in the actionPerformed method

Even after doing this,the "new game" button does not produce any effect

did you add a listener to the button?