Simulating an elevator

[intrepid604]

Hey all, I'm trying to program an "elevator" to move up and down in a frame based on button presses. My problem is that for some reason the elevator won't move to the correct floor. In fact it's moving to locations between floors. I'm sure it's just something stupid I've done--does anyone have any ideas?

Thanks!

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

public class Q1813 extends JApplet {
 
  private Elevator elevator = new Elevator();

  public void init() {
    // Create left buttons
    ButtonPanel lb = new ButtonPanel(elevator);
    //Create right buttons
    ButtonPanel rb = new ButtonPanel(elevator);
    // Set applet layout
    setLayout(new BorderLayout());
    add(lb, BorderLayout.WEST);
    add(rb, BorderLayout.EAST);
    add(elevator, BorderLayout.CENTER);
  }

  // Enable the applet to run standalone
  // Main method
  public static void main(String[] args) {
    // Create a frame
    JFrame frame = new JFrame("Elevator Simulation");

    // Create an instance of the applet
    Q1813 applet = new Q1813();

    // Add the applet instance to the frame
    frame.add(applet, BorderLayout.CENTER);

    // Invoke init() and start()
    applet.init();
    applet.start();

    // Display the frame
    frame.setSize(800, 500);
	frame.setLocationRelativeTo(null);
	frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	frame.setVisible(true);
	
  }
}

//The elevator class encapsulates elevator operations
class Elevator extends JPanel {
  private boolean isUp;            // Moving up or down?
  private int numberFloors=7;
  private int destinationFloor = 0;    // Elevator destination floor
  private int currentFloor=7;
  private int width = 30;  // Elevator width
  private int height; // Elevator height
  private int x = 50;    // The x coordinator of the elevator's upper left corner
  private int currentY = 0 ; // Elevator current location
  private int dy = 4; // Moving interval
  private Timer timer = new Timer(200, new Listener()); // Run the while loop on a separate thread


  public Elevator() {    
    setBackground(Color.yellow); // Set elevator background color
  }

  // Set elevator color
  public void setColor(Color color) {
    setForeground(color);
  }

  // Move the elevator to destination
  public void move(int toFloor) {
    destinationFloor = toFloor;
    //System.out.println("destinationfloor="+destinationFloor);
    move();
  }

  private void move() {
      
        if (destinationFloor > currentFloor) // Moving up
        isUp = true;
      else  // Moving down
          isUp = false;
        
        timer.start();   
      }
  
  class Listener implements ActionListener {
      public void actionPerformed(ActionEvent e) {
        
          if (isUp) { // Moving up
          if (currentFloor < destinationFloor) {
              currentY = currentY - dy;
              repaint();
          }
          else 
              timer.stop();
        }
        else  {  // Moving down
          if (currentFloor > destinationFloor) {
              currentY=currentY+dy;
              repaint();
          }
          else
              timer.stop();
        }
      }
  }

  // Paint elevator
  public void paintComponent(Graphics g) {
    super.paintComponent(g);
    //System.out.println("currentY="+currentY);
    height = getHeight() /numberFloors;
   
   currentFloor=(int)(numberFloors-numberFloors*((double)currentY/getHeight()));
   //System.out.println("currentfloor="+currentFloor);
   
    g.fillRect(x, currentY, width, height);
  }
}

//The ButtonPanel encapsulates buttons
class ButtonPanel extends JPanel {
  private Elevator elevator;    // The elevator
  
  private JButton floor7=new JButton("Floor 7");
  private JButton floor6=new JButton("Floor 6");
  private JButton floor5=new JButton("Floor 5");
  private JButton floor4=new JButton("Floor 4");
  private JButton floor3=new JButton("Floor 3");
  private JButton floor2=new JButton("Floor 2");
  private JButton floor1=new JButton("Floor 1");
  
  ButtonPanel(Elevator elevator) {
    // Pass the elevator, frame, status to the button panel
    this.elevator = elevator;  
    setLayout(new GridLayout(7,1));
    add(floor7);
    add(floor6);
    add(floor5);
    add(floor4);
    add(floor3);
    add(floor2);
    add(floor1);
   
    setBackground(Color.blue);
  
    floor7.addActionListener(new ButtonListener());
    floor6.addActionListener(new ButtonListener());
    floor5.addActionListener(new ButtonListener());
    floor4.addActionListener(new ButtonListener());
    floor3.addActionListener(new ButtonListener());
    floor2.addActionListener(new ButtonListener());
    floor1.addActionListener(new ButtonListener());
  }

  class ButtonListener implements ActionListener {
      // Handle button actions
      public void actionPerformed(ActionEvent e) {
        if (e.getSource() instanceof JButton)
          {
              if (e.getSource()==floor7) // pressed floor7 button
              {
                 elevator.move(7);
              }
              if (e.getSource()==floor6) // pressed floor6 button
              {
                 elevator.move(6);
              }
              if (e.getSource()==floor5) // pressed floor5 button
              {
                 elevator.move(5);
              }
              if (e.getSource()==floor4) // pressed floor4 button
              {
                 elevator.move(4);
              }
              if (e.getSource()==floor3) // pressed floor3 button
              {
                 elevator.move(3);
              }
              if (e.getSource()==floor2) // pressed floor2 button
              {
                 elevator.move(2);
              }
              if (e.getSource()==floor1) //pressed floor1 button
              {
                 elevator.move(1);    
              }
           }    
      }
  }
}

[pbrockway2]

My problem is that for some reason the elevator won't move to the correct floor. In fact it's moving to locations between floors.

Running the program it seems that the elevator stops when its base is first inside any part of the target floor.

I wonder if

currentFloor=(int)(numberFloors-numberFloors*((double)currentY/getHeight()));

isn't suspect in some way. I would throw System.out.println()s in there and check that currentFloor is being calculated correctly. (Define, in advance, what you mean for the elevator to "be" at a given floor.)

------------------------

Why add the elevators and buttons to an applet and then add the applet to a frame? (I'm not saying this is wrong - it's not something I've come accross before, just asking). I would have added the panel to a frame or an applet depending on what was wanted.

Also I find it a bit odd to calculate the floor in the paintComponent() method. SHouldn't that method just paint? You might find it easier to model the behaviour of the elevator in a class that is quite separate from the gui.

[xinnkl]

Hi mate, I try your code, and find a way to fix the problem, It looks like need one more condition to check when elevator going down
as below:


if (isUp) { // Moving up
if (currentFloor < destinationFloor) {
currentY = currentY - dy;
repaint();
}
else
timer.stop();
}
else
{ // Moving down
if (currentFloor > destinationFloor)
{
currentY = currentY + dy;
repaint();
}
else if(currentFloor == destinationFloor)
{
currentY = currentY + dy;
repaint();
}
else
timer.stop(); }
}
}

hope have some help.

[JosAH]

Years ago I was in Spain in an ancient building which had an ancient elevator. It responded just like your simulation does: when the elevator had reached a certain floor, more or less, it stopped and you had to crawl out and jump down to the floor or climb a bit up to be able to reach the floor. Elderly people who couldn't make it had to jump up and down in the elevator to adjust its level somewhat. It was a fun elevator ;-)

kind regards,

Jos

[xinnkl]

I find this problem as well, as a good elevator, this maybe kill somebody sometime, so It should be a good solution when elevator during going down process the last step is up one more step to keep right position.

thank your remian me.
[/I]