Images won't show on Display

Question

hey, i'm just starting out with MIDP programming. i created a MIDlet with a Canvas and tried to display an image but it just doesn't show. at first i didn't get any errors or exceptions but after a bit of tweaking i got this exception:
java.io.IOException
        at javax.microedition.lcdui.ImmutableImage.getImageFromStream(Image.java:971)
        at javax.microedition.lcdui.ImmutableImage.<init>(Image.java:942)
        at javax.microedition.lcdui.Image.createImage(Image.java:310)
        at hello.MyCanvas.paint(GraphicsMIDlet.java:62)
        at javax.microedition.lcdui.Canvas.callPaint(Canvas.java:1074)
        at javax.microedition.lcdui.Display.repaint(Display.java:1566)
        at javax.microedition.lcdui.Display.registerNewCurrent(Display.java:1872)
        at javax.microedition.lcdui.Display.access$700(Display.java:221)
        at javax.microedition.lcdui.Display$DisplayAccessor.foregroundNotify(Display.java:2344)
        at javax.microedition.lcdui.Display$DisplayManagerImpl.notifyWantsForeground(Display.java:3126)
        at javax.microedition.lcdui.Display$DisplayManagerImpl.access$100(Display.java:2565)
        at javax.microedition.lcdui.Display.setCurrent(Display.java:843)
        at hello.GraphicsMIDlet.startApp(GraphicsMIDlet.java:19)
        at javax.microedition.midlet.MIDletProxy.startApp(MIDletProxy.java:43)
        at com.sun.midp.midlet.Scheduler.schedule(Scheduler.java:374)
        at com.sun.midp.main.Main.runLocalClass(Main.java:466)
        at com.sun.midp.main.Main.main(Main.java:120)and here's my MIDlet's code:
package hello;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import java.io.IOException;
public class GraphicsMIDlet extends MIDlet
  private Display  display;
  private MyCanvas canvas;
  public GraphicsMIDlet ()
    display = Display.getDisplay(this);
    canvas  = new MyCanvas(this);
  protected void startApp()
    display.setCurrent( canvas );
  protected void pauseApp()
  protected void destroyApp( boolean unconditional )
  public void exitMIDlet()
    destroyApp(true);
    notifyDestroyed();
class MyCanvas extends Canvas implements CommandListener
  private Command exit;
  private Command refresh;
  private GraphicsMIDlet filledRectangleExample;
  Image img;
  public MyCanvas (GraphicsMIDlet filledRectangleExample)
    this. filledRectangleExample = filledRectangleExample;
    exit = new Command("Exit", Command.EXIT, 1);
    refresh = new Command("Refresh", Command.OK, 2);
    addCommand(exit);
    addCommand(refresh);
    setCommandListener(this);
    img = null;
  public void paint(Graphics graphics)
    graphics.setColor(255,255,255);
    graphics.fillRect(0, 0, getWidth(), getHeight());
    graphics.setColor(0, 0, 255);
    graphics.drawLine(2, 2, 19, 19);
    graphics.setColor(0, 255, 0);
    graphics.fillRoundRect(20, 20, 60, 60, 15, 45);
    graphics.setColor(0, 0, 0);
    graphics.drawString("Hello World", 10, 100, 0);
    if (img == null) {
            try {
                img = Image.createImage("/ball.png");
                //setFullScreenMode(true);
            } catch (IOException e) {
                e.printStackTrace();
                return;
    else if (img != null){
        graphics.drawImage(img, 100, 100, Graphics.VCENTER);
  public void commandAction(Command command, Displayable displayable)
    if (command == exit)
        filledRectangleExample.exitMIDlet();
}i have no idea what exception means or how to fix it. the other graphics show on the screen without a problem. i also tried both jpg and png formats, none seem to work. did i get the image's destination wrong? the images showed up in the projects window so i assumed that i got it right. if not then which folder should i put the images in? or what am i doing wrong?

Answer 1

line # 74 refers to the drawimage method, after editing the code drawimage is currently in line # 73
ok i removed the constructor for the MIDlet class and moved everything to startApp()
moved the image to the MIDlet class and initialized it in startApp() also
the image did have transparent pictures so i changed it and put an image with no transparent or partially transparent pixels
added repaint() method to the refresh command event cause i realized the first time paint is done the image isn't initialized yet so i get no errors sometimes and still don't see the image. (should i repaint in the MIDlet class instead?)
created a res folder in the project's folder and added it to the resources in the project and copied the images folder from the src folder to there, so its in both folders
commented the other draw functions as you suggested
removed the anchor and put its integer value instead (Graphics.TOP = 16)
here's what my code currently looks like:
package hello;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import java.io.IOException;
public class GraphicsMIDlet extends MIDlet
  private Display  display;
  private MyCanvas C;
  Image img = null;
  protected void startApp()
    display = Display.getDisplay(this);
    C  = new MyCanvas(this);
    display.setCurrent( C );
    img = null;
    if (img == null) {
            try {
                img = Image.createImage("/images/Duke.png");
                //setFullScreenMode(true);
            } catch (IOException e) {
                e.printStackTrace();
                return;
  protected void pauseApp()
  protected void destroyApp( boolean unconditional )
  public void exitMIDlet()
    destroyApp(true);
    notifyDestroyed();
class MyCanvas extends Canvas implements CommandListener
  private Command exit;
  private Command refresh;
  private GraphicsMIDlet filledRectangleExample;
  //Timer t;
  public MyCanvas (GraphicsMIDlet filledRectangleExample)
      //t = new Timer();
      this. filledRectangleExample = filledRectangleExample;
      exit = new Command("Exit", Command.EXIT, 1);
      refresh = new Command("Refresh", Command.OK, 2);
      addCommand(exit);
      addCommand(refresh);
      setCommandListener(this);
  public void paint(Graphics graphics)
//    graphics.setColor(255,255,255);
//    graphics.fillRect(0, 0, getWidth(), getHeight());
//    graphics.setColor(0, 0, 255);
//    graphics.drawLine(2, 2, 19, 19);
//    graphics.setColor(0, 255, 0);
//    graphics.fillRoundRect(20, 20, 60, 60, 15, 45);
//    graphics.setColor(0, 0, 0);
//    graphics.drawString("Hello World", 10, 100, 0);
    if (filledRectangleExample.img != null){
        graphics.drawImage(filledRectangleExample.img, 0, 0, 16);
  public void commandAction(Command command, Displayable displayable)
    if (command == exit)
        filledRectangleExample.exitMIDlet();
    else if (command == refresh){
        repaint();
}i debugged the program again, i put a break point at the draw image condition. the first time the paint function runs the image value is null so drawimage is never executed, when i press refresh and repaint is called, the image's value isn't null and drawimage is executed. at that point i get this exception :
java.lang.IllegalArgumentException:
        at hello.MyCanvas.paint(GraphicsMIDlet.java:73)
        at javax.microedition.lcdui.Canvas.callPaint(Canvas.java:1074)
        at javax.microedition.lcdui.Display.repaint(Display.java:1566)
        at javax.microedition.lcdui.Display$DisplayAccessor.repaint(Display.java:2264)
        at javax.microedition.lcdui.Display$DisplayManagerImpl.repaint(Display.java:3012)
        at com.sun.midp.lcdui.DefaultEventHandler.repaintScreenEvent(DefaultEventHandler.java:394)
        at com.sun.midp.lcdui.DefaultEventHandler$QueuedEventHandler.run(DefaultEventHandler.java:665)line 73 refers to drawimage()
i've yet to try using a Form class and using image item, i'll let you know as soon as i do that. also i'm gonna try tinkering with the ready made example i have and see if i find out what i'm doing wrong.
thanks i really appreciate your help