Thread: [Help] Snake algorithm

I've been making a snake game, and everything works, tho the algorythm of the snake movement isnt that good, but its fine.
Now, I also have an apple on the screen, and the problem is i can't figure out a way to find if the snakes head & the apple have even 1 common point.

this is the code of the screen & apple:

Screen:

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package Snake;
 
import Tools.ThreadTool;
import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.*;
import javax.swing.*;
 
/**
 *
 * @author User
 */
public class Screen extends JFrame implements Runnable,KeyListener{
private int difficulty;    
private int direction; //0-up 1- down 2-left 3- right
 
private Thread t;
 
private ArrayList<Integer> snakeX,snakeY;
 
private panel panel;
 
private int w,h;
 
private Apple apple;
 
    public Screen(int difficulty,int sW,int sH){
        super("Snake");
        this.difficulty = difficulty;
 
        this.setDefaultCloseOperation(EXIT_ON_CLOSE);
        this.setSize(sW, sH);
        this.setLocationRelativeTo(null);
 
        snakeX = new ArrayList<Integer>();
        snakeY = new ArrayList<Integer>();
 
        //set width and height of snake
        w = sW/40;
        h=w;
 
        //add head
        snakeX.add(this.getWidth()/2);
        snakeY.add(this.getHeight()/2);
 
        direction = (int)(Math.random()*4);
 
        apple = new Apple(this, w, h);
        apple.generateApple();
 
        panel = new panel();
        panel.setBackground(new Color(0, 153, 51)); //dark green
        add(panel);
 
        this.addKeyListener(this);
    }
 
    @Override
    public void run() {
        while(isAlive()){ // change to alive
                for(int i=snakeX.size();i>1 && snakeX.size() == snakeY.size();i--){
                    snakeX.set(i-1, snakeX.get(i-2));
                    snakeY.set(i-1, snakeY.get(i-2));
                }
 
                if(direction==0){
                    snakeY.set(0, snakeY.get(0)-h);
                    if(/*snakeX.get(0) == apple.getX() && */snakeY.get(0) == apple.getY())
                    {
                        snakeX.add(snakeX.get(snakeX.size()-1));
                        snakeY.add(snakeY.get(snakeY.size()-1)+h);
                    }
                }
                else if(direction==1)
                    snakeY.set(0, snakeY.get(0)+h);
                else if(direction==2)
                        snakeX.set(0, snakeX.get(0)-w);
                else if(direction==3)
                    snakeX.set(0, snakeX.get(0)+w);
 
 
            repaint();
            ThreadTool.sleep(t, 300/(difficulty+1));
        }
    }
 
    public void startThread(){
        t = new Thread(this);
        t.start();
    }
 
    private boolean isAlive(){
        return snakeX.get(0)>=0 && snakeX.get(0)+w<=this.getWidth() && snakeY.get(0)>=0 && snakeY.get(0)+h<=this.getHeight();
    }
 
    @Override
    public void keyTyped(KeyEvent e) {
    }
 
    @Override
    public void keyPressed(KeyEvent e) {
        if(e.getKeyCode()==KeyEvent.VK_RIGHT && direction != 2)
            direction=3;
        else if(e.getKeyCode()==KeyEvent.VK_LEFT && direction !=3)
            direction = 2;
        else if(e.getKeyCode()==KeyEvent.VK_UP && direction!=1)
            direction=0;
        else if(e.getKeyCode()==KeyEvent.VK_DOWN && direction!=0)
            direction = 1;
    }
 
    @Override
    public void keyReleased(KeyEvent e) {
    }
 
    class panel extends JPanel{
        public void paintComponent(Graphics g){
            super.paintComponent(g);
            apple.drawMe(g);
            for(int i=0;i<snakeX.size() && snakeX.size() == snakeY.size();i++){
                g.setColor(Color.green);
                g.fillRect(snakeX.get(i), snakeY.get(i), w, h);
                g.setColor(Color.black);
                g.drawRect(snakeX.get(i), snakeY.get(i), w, h);
                System.err.println("painting at " + snakeX.get(i) + ", " + snakeY.get(i)+","+i);
            }
        }
    }
}

Apple:

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package Snake;
 
import java.awt.Color;
import java.awt.Graphics;
 
/**
 *
 * @author User
 */
public class Apple {
private Screen screen;
private int x,y;
private int w,h;
 
    public Apple(Screen screen,int w,int h){
        this.screen = screen;
        this.w = w;
        this.h = h;
    }
 
    public void generateApple(){
        x = (int)(Math.random()*( (screen.getWidth() - w) - 0 + 1) + 0);
        y=(int)(Math.random()*( ( screen.getHeight() - h) - 0 + 1) + 0);
    }
 
    public void drawMe(Graphics g){
        g.setColor(Color.red);
        g.fillRect(x, y, w, h);
        g.setColor(Color.black);
        g.drawRect(x, y, w, h);
    }
 
    public int getX(){
        return x;
    }
 
    public int getY(){
        return y;
    }
}