Java Programming

I need immediate help on how to make the elevator move from floor to floor... this is not using java applet... I'll paste the program that I have done so far... I don't know how to use timers and listeners in order to make the Elevator move.... Wat should I do...


Here is my program:


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

//The main class
public class Elevator_Simulation extends JFrame
{
public JLabel state; // display the state of the elevator
private JLabel id; //your name and group
public ButtonPanel control; //the button control panel
private Elevator elevator; // the elevator area

//constructor
public Elevator_Simulation()
{
// Create GUI

setTitle("Elevator Simulation");
getContentPane().add(new ButtonPanel(), BorderLayout.WEST);
id = new JLabel(" Name: Abinaya Vasudevan Group:SE3");

getContentPane().add(id, BorderLayout.NORTH);
}

// Main method
public static void main(String[] args)
{
// Create a frame and display it
Elevator_Simulation frame = new Elevator_Simulation();
frame.setSize(800,800);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new Elevator(frame));

//Get the dimension of the screen
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
int screenWidth = screenSize.width;
int screenHeight = screenSize.height;

int x = (screenWidth - frame.getWidth())/2;
int y = (screenHeight - frame.getHeight())/2;

frame.setLocation(x,y);
frame.setVisible(true);
}
} //the end of Elevator_Simulation class

//The ButtonPanel class receives and handles button pressing events
class ButtonPanel extends JPanel implements ActionListener
{
public JButton b[] = new JButton[8]; // 8 Buttons
public boolean bp[] = new boolean[8]; // the state of each button, pressed or not

//constructor
public ButtonPanel()
{
//create GUI
setLayout(new GridLayout(8,1));

for (int i=1; i<=8; i++)
{
b[8-i] = new JButton("F"+(8-(i-1)));
b[8-i].addActionListener(this);
add(b[8-i]);
}
}

public void actionPerformed(ActionEvent e)
{
//handle the button pressing events
bp[8-((int)(e.getActionCommand().charAt(1)))] = true;

}
} //the end of ButtonPanel class

// The elevator class draws the elevator area and simulates elevator movement
class Elevator extends JPanel implements ActionListener
{
//Declaration of variables
private Elevator_Simulation app; //the Elevator Simulation frame
private boolean up; // the elevator is moving up or down
private int width; // Elevator width
private int height; // Elevator height
private int xco; // The x coordinate of the elevator's upper left corner
private int yco; // The y coordinate of the elevator's upper left corner
private int dy0; // Moving interval
private int topy; //the y coordinate of the top level
private int bottomy; // the y coordinate of the bottom level
private Timer tm; //the timer to drive the elevator movement
//other variables to be used ...

//constructor
public Elevator(Elevator_Simulation app)
{
//necessary initialization
tm = new Timer(1000, this);
tm.setInitialDelay(300);
tm.start();

}

// Paint elevator area
public void paintComponent(Graphics g)
{
//obtain geometric values of components for drawing the elevator area
xco = getWidth()/2-10;
yco = getHeight()/2-20;
width = 10;
height = 20;
//clear the painting canvas
super.paintComponent(g);
//start the Timer if not started elsewhere
if(!tm.isRunning())
tm.start();
//draw horizontal lines and the elevator
g.setColor(Color.magenta);
g.drawLine(0,0,getWidth(), 0);
g.drawLine(0,93,getWidth(), 93);
g.drawLine(0,186,getWidth(), 186);
g.drawLine(0,279,getWidth(), 279);
g.drawLine(0,372,getWidth(), 372);
g.drawLine(0,465,getWidth(), 465);
g.drawLine(0,558,getWidth(), 558);
g.drawLine(0,651,getWidth(), 651);
g.drawLine(0,744,getWidth(), 744);
g.drawLine(0,837,getWidth(), 837);

g.setColor(Color.black);
g.fill3DRect(getWidth()/2 - 50, 93, 100, 93, true);
g.setColor(Color.magenta);
g.drawLine(getWidth()/2, 93, getWidth()/2, 186);
}

//Handle the timer events
public void actionPerformed(ActionEvent e)
{
//loop if the elevator needs to be stopped for a while

//adjust Y coordinate to simulate elevetor movement
//change moving direction when hits the top and bottom
//repaint the panel
//update the state of the elevator
}
} //the end of Elevator class


The skeleton was provided but I am still not sure how to do it... So pls help... asap....