Hi guys i am working on a java car park simulation which controls the entry and departures of cars using the parking lot, the coding so far is below, but when i compile it i get 8 error messages, i have attached the errors message on the page...if anyone can tell me where i am going wrong.


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


/*********************CARPARK CONTROL*****************************/

class CarParkControl {

    protected int spaces;
    protected int capacity;

    CarParkControl(int n) {
        capacity = spaces = n;
    }

    void arrive() throws InterruptedException {
		// to do
		--spaces;

    }

    void depart() throws InterruptedException {
		// to do
		++spaces;
    }
}

/*******************ARRIVALS************************/

class Arrivals implements Runnable {

    CarParkControl carpark;

    Arrivals(CarParkControl c) {
        carpark = c;
    }

    public void run() {
      try {
        while(true) {
           ThreadPanel.rotate(330);
           carpark.arrive();
           ThreadPanel.rotate(30);
        }
      } catch (InterruptedException e){}
    }
}

/********************DEPARTURES*******************************/

class Departures implements Runnable {

    CarParkControl carpark;

    Departures(CarParkControl c) {
        carpark = c;
    }

    public void run() {
      try {
        while(true) {
            ThreadPanel.rotate(180);
            carpark.depart();
            ThreadPanel.rotate(180);

        }
      } catch (InterruptedException e){}
    }
}

/****************************APPLET**************************/

public class CarPark extends Applet {

    final static int Places = 4;

    ThreadPanel arrivals;
    ThreadPanel departures;
    CarParkCanvas carDisplay;

    public void init() {
        super.init();
         // Set up Display
        arrivals = new ThreadPanel("Arrivals",Color.blue);
        departures = new ThreadPanel("Departures",Color.yellow);
        carDisplay = new CarParkCanvas("CarPark",Places,this);
        GridBagLayout gridbag = new GridBagLayout();
        setLayout(gridbag);
        GridBagConstraints gc = new GridBagConstraints();
        gc.anchor = GridBagConstraints.NORTH;
        gridbag.setConstraints(carDisplay, gc);
        gridbag.setConstraints(arrivals, gc);
        gridbag.setConstraints(departures, gc);
        add(arrivals);
        add(carDisplay);
        add(departures);
    }

    public void start() {
        CarParkControl c = new DisplayCarPark(carDisplay,Places);
        arrivals.start(new Arrivals(c));
        departures.start(new Departures(c));
    }


    public void stop() {
        arrivals.stop();
        departures.stop();
    }

}

/**************************************************************/

class DisplayCarPark extends CarParkControl {

    CarParkCanvas disp;
    boolean occupied[];

    DisplayCarPark(CarParkCanvas disp,int size) {
        super(size);
        this.disp = disp;
        occupied = new boolean[size];
        for (int i=0; i<size; i++) occupied[i]=false;
    }

    private void display() {
        disp.setvalue(spaces,occupied);
    }

    synchronized public void arrive() throws InterruptedException {
        super.arrive();
        occupied[place(false)]=true;
        display();
        Thread.sleep(400);
    }

    synchronized public void depart() throws InterruptedException {
        super.depart();
        occupied[place(true)]=false;
        display();
    }

    private int place(boolean v) {
        int start = ((int)(Math.random() * 1000))% capacity;
        for (int i =0; i<capacity; i++) {
            int j = (start + i) % capacity;
            if(occupied[j] == v) return j;
        }
        return 0; //should never happen
    }

 }

/**************************************************************/

class CarParkCanvas extends Canvas {
    String title;
    int slots;
    int spaces;
    boolean occupied[];
    Applet applet;
    Image  car;

    Font f1 = new Font("Helvetica",Font.ITALIC+Font.BOLD,24);
    Font f2 = new Font("TimesRoman",Font.BOLD,36);

    CarParkCanvas(String title, int slots, Applet applet) {
        super();
        this.title=title;
        this.slots=slots;
        spaces = slots;
        this.applet = applet;
        this.occupied = new boolean[slots];
        for (int i=0; i<slots; i++) occupied[i] = false;
        resize(20+50*slots,150);
        setBackground(Color.cyan);
        MediaTracker mt;
        mt = new MediaTracker(this);
        car = applet.getImage(applet.getDocumentBase(), "image/car.gif");
        mt.addImage(car, 0);
        try {
            mt.waitForID(0);
        } catch (java.lang.InterruptedException e) {
            System.out.println("Couldn't load car image");
        }
  	}

    public void setvalue(int spaces, boolean occupied[]){
        this.spaces = spaces;
        this.occupied = occupied;
        repaint();
    }

    public void paint(Graphics g) {
        update(g);
    }

    Image offscreen;
    Dimension offscreensize;
    Graphics offgraphics;

    public synchronized void update(Graphics g){
        Dimension d = size();
	    if ((offscreen == null) || (d.width != offscreensize.width)
	                            || (d.height != offscreensize.height)) {
	        offscreen = createImage(d.width, d.height);
	        offscreensize = d;
	        offgraphics = offscreen.getGraphics();
	        offgraphics.setFont(getFont());
	    }

	    offgraphics.setColor(getBackground());
	    offgraphics.fillRect(0, 0, d.width, d.height);

         // Display the title
        offgraphics.setColor(Color.black);
        offgraphics.setFont(f1);
        FontMetrics fm = offgraphics.getFontMetrics();
        int w = fm.stringWidth(title);
        int h = fm.getHeight();
        int x = (size().width - w)/2;
        int y = h;
        offgraphics.drawString(title, x, y);
        offgraphics.drawLine(x,y+3,x+w,y+3);
        // CarPark Places
        y = h+10;
        offgraphics.setColor(Color.white);
        offgraphics.fillRect(10,y,50*slots,100);
        offgraphics.setColor(Color.black);
        for(int i=0; i<slots; i++) {
            offgraphics.drawRect(10+50*i,y,50,100);
        }
        offgraphics.setColor(Color.white);
        for(int i=1; i<slots; i++) {
            offgraphics.drawLine(10+50*i,y+60,10+50*i,y+99);
        }
        //arrival gate
        if (spaces==0)
             offgraphics.setColor(Color.black);
        else
             offgraphics.setColor(Color.white);
        offgraphics.fillRect(8,y+60,5,39);
        //departure gate
        if (spaces==slots)
             offgraphics.setColor(Color.black);
        else
             offgraphics.setColor(Color.white);
        offgraphics.fillRect(8+50*slots,y+60,5,39);
        //Display Cars
        offgraphics.setColor(Color.blue);
        for (int i=0; i<slots; i++) {
          if (occupied[i])
            offgraphics.drawImage(car,15+50*i,y+5,this);
        }
        g.drawImage(offscreen, 0, 0, null);
    }
}

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any advice appreaciated...cheers
tc.

Code tags and formatting please. All your errors appear to be due to the fact that you refer to a ThreadPanel class, but you do not provide one so it doesn't know what to do when it sees the word ThreadPanel in your code.

thanks its sorted now. tc

Could someone help me with a problem? I don't understand the code exactly..