The code below is for tic tac toe in Jcreator but I can't get it to swtich turns. What am I doing wrong?

Code:
/**
 * @(#)tictactoe.java
 *
 * tictactoe Applet application
 *
 * @author
 * @version 1.00 2012/3/27
 */

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

public class tictactoe extends java.applet.Applet implements MouseListener, MouseMotionListener {

	int x, y;
	boolean one, two, three, four, five, six, seven, eight, nine, square, circle, clicked;

	public void init() {

		addMouseListener(this);
		addMouseMotionListener(this);
		square=true;

	}

	public void paint(Graphics screen) {

		screen.drawLine(200,0,200,600);
		screen.drawLine(400,0,400,600);
		screen.drawLine(0,200,600,200);
		screen.drawLine(0,400,600,400);
		
		if(one==true) {
			if(square==true) {
				screen.drawRect(10,10,180,180);
			}
			if(circle==true) {
				screen.drawOval(10,10,180,180);
			}
		}
		
		if(two==true) {
			if(square==true) {
				screen.drawRect(210,10,180,180);
			}
			if(circle==true) {
				screen.drawOval(210,10,180,180);
			}
		}
		
		if(three==true) {
			if(square==true) {
				screen.drawRect(410,10,180,180);
			}
			if(circle==true) {
				screen.drawOval(410,10,180,180);
			}
		}
		
	}

	public void mouseClicked(MouseEvent event) {

		x=event.getX();
		y=event.getY();

		if(x>0 && x<200 && y>0 && y<200) {
			one=true;
			repaint();
		}
		if(x>200 && x<400 && y>0 && y<200) {
			two=true;
			repaint();
		}
		if(x>400 && x<600 && y>0 && y<200) {
			three=true;
			repaint();
		}
		
		checkturn();
		clicked=true;


	}
	public void mouseReleased(MouseEvent event) {
	}
	public void mousePressed(MouseEvent event) {
	}
	public void mouseEntered(MouseEvent event) {
	}
	public void mouseExited(MouseEvent event) {
	}
	public void mouseDragged(MouseEvent event) {
	}
	public void mouseMoved(MouseEvent event) {
	}

	public void checkturn() {

		if(clicked==true && square==true) {

			clicked=false;
			square=false;
			circle=true;

		}
		if(clicked==true && circle==true) {

			clicked=false;
			circle=false;
			square=true;

		}

	}

}