Elevator Simulation using GUI... HELP!

Question

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....

Answer 1

I've figured out the movement part... But why doesnt my variable state get set into the new String values? And how do I make it stop at the respective floors when the buttons are pressed?
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 = new ButtonPanel(); //the button control panel
   private Elevator elevator; // the elevator area
   //constructor
     public Elevator_Simulation()
        // Create GUI
          setTitle("Elevator Simulation");
          getContentPane().add(control, BorderLayout.WEST);
          id = new JLabel("                                                                                      Name: Abinaya Vasudevan  Group:SE3");
          state = new JLabel("");
          getContentPane().add(state, BorderLayout.SOUTH);
          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]);
          for(int j=0; j<=7; j++)
               bp[j] = false;
   public void actionPerformed(ActionEvent e)
        int buttonNumber = Integer.parseInt(String.valueOf(e.getActionCommand().charAt(1)));
          bp[8 - buttonNumber] = 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
     private int offset;
     private ButtonPanel button;
   //other variables to be used ...
   //constructor
   public Elevator(Elevator_Simulation app)
        //necessary initialization
          tm = new Timer(0, this);
          tm.start();
          up = true;
          offset = 0;
   // Paint elevator area
   public void paintComponent(Graphics g)
          //obtain geometric values of components for drawing the elevator area
          width = getWidth()/8;
          height = getHeight()/8;
          xco = getWidth()/2 -50;
          yco = (height * 7) + offset;
          topy = 0;
          bottomy = height * 7;
          //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,height,getWidth(), height);
          g.drawLine(0,(height*2),getWidth(), (height*2));
          g.drawLine(0,(height*3),getWidth(), (height*3));
          g.drawLine(0,(height*4),getWidth(), (height*4));
          g.drawLine(0,(height*5),getWidth(), (height*5));
          g.drawLine(0,(height*6),getWidth(), (height*6));
          g.drawLine(0,(height*7),getWidth(), (height*7));
          g.drawLine(0,(height*8),getWidth(), (height*8));
          g.setColor(Color.black);
          g.fill3DRect(xco, yco, width, height, true);
          g.setColor(Color.magenta);
          g.drawLine(xco+(width/2), yco, xco+(width/2), (yco+height));
   //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
          if(up && yco > topy)
               offset--;
          if(!up && yco < bottomy)
               offset++;
          if(yco == topy)
               up = false;
               app.state.setText("The elevator is going down");
          if(yco == bottomy)
               up = true;
               app.state.setText("The elevator is going up");
          repaint();          
} //the end of Elevator class