CreateImageIcon problem

In all examples on this site the images are stored in a folder named images. If I want to put a picture into a program, and that picture is in C:\Program Files for example, what should I write ?
Using:
ImageIcon icon = createImageIcon("C:\\Program Files\\picture.gif");is not working.
Any sugestion?
Thanks

you could start by posting the code to createImageIcon(). In any case, a better solution is to put the images in the jar of the application and load them using the classloader. This link shows how to do it for a properties file, I'm sure you can work out how to modify that to an image file:
http://www.javaworld.com/javaworld/javaqa/2003-08/01-qa-0808-property.html

Similar Messages

1.4.2 Java Swing problems

I have a swing application with 2 JComboBox 's, 1 JPanel (for pictures), 1 JButton and a scroll pane. Basicall the JComboBoxes have an action listener that changes the pictures when I cahnge the names. However, I would like the Jbutton when pressed to display the name chosen (from the JComboBox) and display it in the textArea. See code below.
import javax.swing.*;
import javax.swing.Action;
import java.awt.event.ActionEvent;
import java.awt.event.ItemListener;
import java.awt.*;
import java.awt.event.*;
* @author Administrator
* TODO To change the template for this generated type comment go to
* Window - Preferences - Java - Code Style - Code Templates
public class choice_in2 extends JPanel implements ActionListener{
     private JLabel contender1FieldLabel;
     private JLabel contender2FieldLabel;
     private JButton runButton;
     JLabel picture1;
     JLabel picture2;
     //Text area which shows the result
     private JTextArea textArea;
     private JLabel textAreaLabel;
     public choice_in2(){
          //          Create a ChoiceField for the input of first contender
          contender1FieldLabel = new JLabel("Contender1 ",4);
          String[] contender1Strings = { "Bill", "Bob", "Don", "Michael", "John" };
          JComboBox contender1List = new JComboBox(contender1Strings);
          contender1List.setSelectedIndex(1);
          contender1List.addActionListener(new Eavesdropper1(picture1));
          //          Create a ChoiceField for the input of second contender
          contender2FieldLabel = new JLabel("Contender2 ",4);
          String[] contender2Strings = { "Philip", "Timothy", "Tom", "Kenneth", "Stone" };
          JComboBox contender2List = new JComboBox(contender2Strings);
          contender2List.setSelectedIndex(2);
          contender2List.addActionListener(new Eavesdropper2(picture2));
        //Set up the first picture.
        picture1 = new JLabel();
        picture1.setFont(picture1.getFont().deriveFont(Font.ITALIC));
        picture1.setHorizontalAlignment(JLabel.CENTER);
        updateLabel1(contender1Strings[contender1List.getSelectedIndex()]);
        picture1.setBorder(BorderFactory.createEmptyBorder(10,0,0,0));
        //Set up the second picture.
        picture2 = new JLabel();
        picture2.setFont(picture1.getFont().deriveFont(Font.ITALIC));
        picture2.setHorizontalAlignment(JLabel.CENTER);
        updateLabel2(contender2Strings[contender2List.getSelectedIndex()]);
        picture2.setBorder(BorderFactory.createEmptyBorder(10,0,0,0));
        //The preferred size is hard-coded to be the width of the
        //widest image and the height of the tallest image + the border.
        //A real program would compute this.
        picture1.setPreferredSize(new Dimension(200, 220+10));
        picture2.setPreferredSize(new Dimension(200, 220+10));
          // Create a JButton that will compute
          runButton = new JButton("Compute");
          runButton.addActionListener(new Eavesdropper3(textArea));
          // Create a JTextArea that will display the results
          textAreaLabel = new JLabel("Results");
          textArea = new JTextArea(10,70);
          textArea.setFont(new Font("Courier",Font.PLAIN,12));
          JScrollPane scrollPane = new JScrollPane(textArea, JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
          textArea.setEditable(false);
        //Lay out the demo.
        add(contender1List, BorderLayout.WEST);
        add(picture1, BorderLayout.WEST);
        add(contender2List, BorderLayout.EAST);
        add(picture2, BorderLayout.EAST);
        add(runButton, BorderLayout.EAST);
        add(textAreaLabel, BorderLayout.SOUTH);
        add(scrollPane, BorderLayout.SOUTH);
        setBorder(BorderFactory.createEmptyBorder(20,20,20,20));
    /** Listens to the combo box. */
    public void actionPerformed(ActionEvent e) {
    public void updateLabel1(String name1) {
        ImageIcon icon1 = createImageIcon( name1 + ".jpg");
        picture1.setIcon(icon1);
        picture1.setToolTipText("A drawing of a " + name1.toLowerCase());
        if (icon1 != null) {
            picture1.setText(null);
        } else {
            picture1.setText("Image not found");
    public void updateLabel2(String name2) {
         ImageIcon icon2 = createImageIcon( name2 + ".jpg");
        picture2.setIcon(icon2);
        picture2.setToolTipText("A drawing of a " + name2.toLowerCase());
        if (icon2 != null) {
           picture2.setText(null);
        } else {
            picture2.setText("Image not found");
    /** Returns an ImageIcon, or null if the path was invalid. */
    public ImageIcon createImageIcon(String path) {
        java.net.URL imgURL = choice_in2.class.getResource(path);
        if (imgURL != null) {
            return new ImageIcon(imgURL);
        } else {
            System.err.println("Couldn't find file: " + path);
            return null;
    class Eavesdropper2 implements ActionListener {
        JLabel myTextArea;
        public Eavesdropper2(JLabel ta) {
             myTextArea = ta;
        public void actionPerformed(ActionEvent e) {
            JComboBox contender2List = (JComboBox)e.getSource();
            String contender2ListName = (String)contender2List.getSelectedItem();
            updateLabel2(contender2ListName);
            Eavesdropper3 code;
            code = new Eavesdropper3(contender2ListName);
    class Eavesdropper1 implements ActionListener {
        JLabel myTextArea;
        public Eavesdropper1(JLabel tt) {
             myTextArea = tt;
        public void actionPerformed(ActionEvent e) {
            JComboBox contender1List = (JComboBox)e.getSource();
            String contender1ListName = (String)contender1List.getSelectedItem();
            updateLabel1(contender1ListName);
    class Eavesdropper3 implements ActionListener {
         String contender22;
        JTextArea myTextArea;
        public Eavesdropper3(JTextArea bb) {
             myTextArea = bb;
        public Eavesdropper3(String contender2ListName){
             contender22 = contender2ListName;
           * @return Returns the contender22.
          public String getContender22() {
               return contender22;
        public void actionPerformed(ActionEvent e) {
             textArea.setText("Wild Test");
             textArea.append("\n      OUTCOME    \n\n " +getContender22());
}

weebib
We are using Windows XP , Nvidia graphics card, with Multiview. I hope the problem is not specific to the platform.
It is reproducible with 1.4.2 and absent in 1.4.1
camickr
I am new to this forum. didn't know about code blocks.

Jtree Select node and change leafs icon problem

Hi All,
i create a tree and implement a TreeSelectionListener:
my mission is whenever i select a node i need to change the icon of this node (for now.later i will have to find if it have childrens).
import java.awt.Color;
import java.awt.Component;
import java.util.Enumeration;
import java.util.NoSuchElementException;
import java.util.Vector;
import javax.swing.ImageIcon;
import javax.swing.JTree;
import javax.swing.event.TreeExpansionEvent;
import javax.swing.event.TreeExpansionListener;
import javax.swing.event.TreeSelectionEvent;
import javax.swing.event.TreeSelectionListener;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeCellRenderer;
import javax.swing.tree.TreeModel;
import javax.swing.tree.TreeNode;
import javax.swing.tree.TreePath;
public class TreeView{
     DefaultMutableTreeNode top;
     JTree tree ;
     Color frameColor;
     public static ImageIcon NoTSelIcon;
     public static ImageIcon SelIcon;
    public static String[] name= new String[8];
     public TreeView(Color BackColor) {
          // TODO Auto-generated constructor stub
        top = new DefaultMutableTreeNode("Diagnostics");
        this.frameColor=BackColor;
         SelIcon = createImageIcon("../Resource/Images/Select.gif");
         if (SelIcon == null)
             System.err.println("Tutorial icon missing; using default.");
         NoTSelIcon = createImageIcon("../Resource/Images/NotSelc.gif");
           if (NoTSelIcon == null)
             System.err.println("Tutorial icon missing; using default.");
     public Component createTreeComponents(){
            //Create the nodes.
             createNodes(top);
        //Create a tree that allows one selection at a time.
        tree = new JTree(top);
        //TREE LISTENERS
        //Treeselction listener
        Handler hObject = new Handler();
        tree.addTreeSelectionListener(hObject);
       //Tree expand/collapse listener
        HandlerExpansionListener hObjectExpan = new HandlerExpansionListener();
        tree.addTreeExpansionListener(hObjectExpan);
//       tree.getSelectionModel().setSelectionMode(TreeSelectionModel.DISCONTIGUOUS_TREE_SELECTION);
        //set tree background
        tree.setBackground(frameColor);
         tree.setCellRenderer(new OverrideTreeCellRenderer(frameColor,SelIcon,NoTSelIcon));
        return tree;
      private void createNodes(DefaultMutableTreeNode top) {
             DefaultMutableTreeNode category = null;
             DefaultMutableTreeNode SubCategory = null;
             DefaultMutableTreeNode SubCategoryBasee = null;
             DefaultMutableTreeNode SubSubCategoryBasee = null;
             category = new DefaultMutableTreeNode("Dfe");
             top.add(category);
             //Sub test visible
             SubCategory = new DefaultMutableTreeNode("Test Visible");
             category.add(SubCategory);
             SubCategory.add(new DefaultMutableTreeNode("Son 1"));
             SubCategory.add(new DefaultMutableTreeNode("Son 2"));
             SubSubCategoryBasee = new DefaultMutableTreeNode("Test Base");
             SubSubCategoryBasee.add(new DefaultMutableTreeNode("Grandson 1"));
             SubSubCategoryBasee.add(new DefaultMutableTreeNode("Grandson 2"));
             SubCategory.add(SubSubCategoryBasee);
      class Handler implements TreeSelectionListener {
               public void valueChanged(TreeSelectionEvent arg0) {
                    // TODO Auto-generated method stub
                    System.out.println("treeSelect event ");
                    TreePath trph;
                    trph=arg0.getNewLeadSelectionPath();
                    int count=trph.getPathCount();
                    DefaultMutableTreeNode Selnode = (DefaultMutableTreeNode)tree.getLastSelectedPathComponent();
                    String Name = (String)Selnode.getUserObject();
                    setSelected(Selnode,true);
                    int number_ofnodes=getNodeCountBelow((TreeModel)tree.getModel() , Selnode, false);
                    System.out.println("The Number of nodes under "+Name+"="+number_ofnodes);
                    tree.setCellRenderer(new IconRenderer(SelIcon,NoTSelIcon,frameColor));
      class HandlerExpansionListener implements TreeExpansionListener {
               public void valueChanged(TreeSelectionEvent arg0) {
                    // TODO Auto-generated method stub
                    DefaultMutableTreeNode node = (DefaultMutableTreeNode) tree.getLastSelectedPathComponent();
                    if (node == null) return;
                  }     // The inner class
               public void treeCollapsed(TreeExpansionEvent arg0) {
                    // TODO Auto-generated method stub
                    System.out.println("treeCollapsed event ");
               public void treeExpanded(TreeExpansionEvent arg0) {
                    // TODO Auto-generated method stub
                    System.out.println("treeExpanded event ");
      /** Returns an ImageIcon, or null if the path was invalid. */
         protected static ImageIcon createImageIcon(String path) {
              //ImageIcon imcon= new ImageIcon(path);
              //return imcon;
             java.net.URL imgURL = TreeView.class.getResource(path);
             if (imgURL != null) {
                 return new ImageIcon(imgURL);
             } else {
                 System.err.println("Couldn't find file: " + path);
                 return null;
         DefaultMutableTreeNode newnode;
         public void setSelected(DefaultMutableTreeNode Selnode ,boolean isSelected)
                Enumeration Enchilds=Selnode.children();//ENUMRATE ALL CHILDS FOR THIS NODE
             if (Enchilds != null)
                  while (Enchilds.hasMoreElements())
                       newnode=(DefaultMutableTreeNode)Enchilds.nextElement();
                       String NameSel = (String)newnode.getUserObject();
                       setSelected(newnode,isSelected);
         //GETTING THE TREE DEPTH
         public int getNodeCountBelow(TreeModel model, Object node, boolean includeInitialNode)
             int n = includeInitialNode ? 1 : 0;
             for (int i = 0; i < model.getChildCount(node); i ++)
                 n += getNodeCountBelow(model, model.getChild(node, i), true);
             return n;
import java.awt.Color;
import java.awt.Component;
import java.util.Enumeration;
import java.util.NoSuchElementException;
import javax.swing.Icon;
import javax.swing.JTree;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeCellRenderer;
public class IconRenderer extends DefaultTreeCellRenderer {
     private static final long serialVersionUID = 1L;
     Icon SelectedIcon;
     Icon NotSelectedIcon;
     Color BackgroundColor;
     boolean Selected=false;
     boolean Leaf=false;
     boolean IsItaChild=false;
     DefaultMutableTreeNode SelctedNode=null;
    public IconRenderer(Icon SelIcon,Icon NoTSelIcon,Color Bacground) {
         SelectedIcon = SelIcon;
         NotSelectedIcon = NoTSelIcon;
         BackgroundColor=Bacground;
         setBackgroundNonSelectionColor(BackgroundColor);
    public Component getTreeCellRendererComponent(JTree tree,Object value,boolean sel,boolean expanded,
                                                    boolean leaf,int row,boolean hasFocus)
         super.getTreeCellRendererComponent(tree, value, sel,expanded, leaf, row,hasFocus);
         Selected=sel;
         Leaf=leaf;
         DefaultMutableTreeNode node = (DefaultMutableTreeNode) value;
         String s2 = (String)node.getUserObject();
   return this;
}my problem is :
when i select a node the the method "getTreeCellRendererComponent"
start to run on the entire tree from buttom to top and than from top to buttom.
for me it waste of time because if has say 100 nodes it wont botthers me.
but i have 20000 nodes and more its take a time.
and for all this nodes i have to make compares.
is there a way to force the DefaultTreeCellRenderer to not run the entire tree???
Thanks

You need to make sure that your TreeModel interprets your group nodes to be non-leaf nodes (one of the methods in the TreeModel interface is called isLeaf). If you are using a DefaultTreeModel with DefaultMutableTreeNode objects, you can use the askAllowsChildren property of DefaultTreeModel and the allowsChildren property of DefaultMutableTreeNode to control this. See the API for more details:
http://java.sun.com/j2se/1.4.2/docs/api/javax/swing/tree/DefaultTreeModel.html
http://java.sun.com/j2se/1.4.2/docs/api/javax/swing/tree/DefaultMutableTreeNode.html

Text editor problems

import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class TextEditor extends JApplet {
    //Declare and create image icons
    private ImageIcon openImageIcon = ImageViewer.createImageIcon(
            "image/open.gif", this);
    private ImageIcon saveImageIcon = ImageViewer.createImageIcon(
            "image/save.gif", this);
    //Create menu items
    private JMenuItem jmiOpen = new JMenuItem("Open", openImageIcon);
    private JMenuItem jmiSave = new JMenuItem("Save", saveImageIcon);
    private JMenuItem jmiClear = new JMenuItem("Clear");
    private JMenuItem jmiExit = new JMenuItem("Exit");
    private JMenuItem jmiForeground = new JMenuItem("Foreground");
    private JMenuItem jmiBackground = new JMenuItem("Background");
    //Create buttons to be placed in a tool bar
    private JButton jbtOpen = new JButton(openImageIcon);
    private JButton jbtSave = new JButton(saveImageIcon);
    private JLabel jlblStatus = new JLabel();
    //Create a JFileChooser with the current directory
    private JFileChooser jFileChooser1
            = new JFileChooser(new File("."));
    //Create a text area
    private JTextArea jta = new JTextArea();
    public TextEditor() {
        //Add Menu Items to the menu
        JMenu jMenu1 = new JMenu("File");
        jMenu1.add(jmiOpen);
        jMenu1.add(jmiSave);
        jMenu1.add(jmiClear);
        jMenu1.addSeparator();
        jMenu1.add(jmiExit);
        //Add menu items to the OTHER menu
        JMenu jMenu2 = new JMenu("Edit");
        jMenu2.add(jmiForeground);
        jMenu2.add(jmiBackground);
        //Add menus to menus lol
        JMenuBar jMenuBar1 = new JMenuBar();
        jMenuBar1.add(jMenu1);
        jMenuBar1.add(jMenu2);
        //Set the menu bar
        setJMenuBar(jMenuBar1);
        //Create toolbar
        JToolBar jToolBar1 = new JToolBar();
        jToolBar1.add(jbtOpen);
        jToolBar1.add(jbtSave);
        jmiOpen.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e){
                open();
        jmiSave.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent evt){
                save();
        jmiClear.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent evt){
                jta.setText(null);
        jmiExit.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent evt){
                System.exit(0);
        jmiForeground.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent evt){
                Color selectedColor =
                        JColorChooser.showDialog(null, "Choose Foreground Color",
                        jta.getForeground());
                if (selectedColor != null)
                    jta.setForeground(selectedColor);
        jmiBackground.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent evt){
                Color selectedColor =
                        JColorChooser.showDialog(null, "Choose Background Color",
                        jta.getForeground());
                if (selectedColor != null)
                    jta.setBackground(selectedColor);
        jbtOpen.addActionListener( new ActionListener(){
            public void actionPerformed(ActionEvent evt){
                open();
        jbtSave.addActionListener( new ActionListener(){
            public void actionPerformed(ActionEvent evt){
                save();
        getContentPane().add(jToolBar1, BorderLayout.NORTH);
        getContentPane().add(jlblStatus, BorderLayout.SOUTH);
        getContentPane().add(new JScrollPane(jta), BorderLayout.CENTER);
    /** Open file*/
    private void open() {
        if (jFileChooser1.showOpenDialog(this) ==
                JFileChooser.APPROVE_OPTION)
            open(jFileChooser1.getSelectedFile());
    /** Open file with specified File instance*/
    private void open(File file){
        try{
            //Read from the specified file and store it in jta
            BufferedInputStream in = new BufferedInputStream(
                    new FileInputStream(file));
            byte[] b = new byte[in.available()];
            in.read(b, 0, b.length);
            jta.append(new String(b, 0, b.length));
            in.close();
            //Display the staus of the file opening
            jlblStatus.setText(file.getName()+ "opened.");
         catch (IOException ex) {
             jlblStatus.setText("Error opening "+ file.getName());
    /** Save file*/
    private void save() {
        if (jFileChooser1.showSaveDialog(this) ==
                JFileChooser.APPROVE_OPTION){
            save(jFileChooser1.getSelectedFile());
    /**Save file with specified File instance */
    private void save(File file) {
        try{
            //Write the sext in jta to the specified file
            BufferedOutputStream out = new BufferedOutputStream(
                    new FileOutputStream(file));
            byte[] b = (jta.getText()).getBytes();
            out.write(b, 0, b.length);
            out.close();
            //Display this status of the save file operation
            jlblStatus.setText(file.getName() + "saved.");
        catch (IOException ex) {
            jlblStatus.setText("Error saving" + file.getName());
}There is a problem with this part of the code:
private ImageIcon openImageIcon = ImageViewer.createImageIcon(
            "image/open.gif", this);
    private ImageIcon saveImageIcon = ImageViewer.createImageIcon(
            "image/save.gif", this);It says it can't find the variable ImageViewer .
Please help :(
Thanks in advance.

What is ImageViewer? It doesn't appear to be a class in Java 5.0 or Java 6.0.
I can't see an import statement for it -are you expecting it to exist in the same folder as your TextEditor class?

Problem with netbeans IDE

hey! i am a learner of j2se 5.0 and am horrible at command line compiling. so i use netbeans IDE and well it has been doing excellently till now.
recently i had a porblem with ImageIcons and i found the exact problem which i was having but with repect to applets , that is, the images were not displaying properly. i have managed to solve the problem as far as applets are concerned, but it is not so with applications.
the thing is when i use the run function of the IDE, it displays all icons perfectly and its as if nothing is wrong.
it creates a .jar file which when i separately click to execute by going to its folder, does so but does not display any images. In fact it executes and behaves in such a way that it's exactly as if i have not used icons in the program- it displays everything else. should i change some setting of the IDE? but if some setting is to be changed, y is it running normally when run from the IDE( F6 key).
also when i used the command line (after some research to learn to use it) to extract all files from the .jar file, all the images were in it!!!as well as all the class files. so i can't even say that the IDE has not bundled up the images into the .jar file.
could some1 please help??i need help with .jar files and not applets.

first i deefined a method as shown in the Java tutorial
ImageIcon icon =createImageIcon("lion.jpg","name");
( within the contructor of the class)
then after completing the constructor for the class- (I am trying to display an ImageIcon on the background of a JFrame)
i provided the following definition after the constructor and b4 the main method:
protected static ImageIcon createImageIcon(String path,
String description) {
java.net.URL imgURL = LabelDemo.class.getResource(path);
if (imgURL != null) {
return new ImageIcon(imgURL, description);
} else {
System.err.println("Couldn't find file: " + path);
return null;
this is what i did-and when run from the IDE-it is perfect, but the jar file ggenerated when executed displays every single thing-all swing components e.t.c EXCEPT the image
the image is in the same folder as the source file- i checked because if not, an error is indicated- so that is not the problem here.
this same exact code works perfectly with applets and they execute perfectly both from the IDE and also when executed separately.
the same problem also iccurs when trying to display on labels and buttons.(only for JFrames not for JApplets)
the thing is in the java tutorial the method is given for applets and so my applets worked -so is there somethin i'm missing for frames- as far as i know they r very similar as far as usage is concerned.

A problem with threads

I am trying to implement some kind of a server listening for requests. The listener part of the app, is a daemon thread that listens for connections and instantiates a handling daemon thread once it gets some. However, my problem is that i must be able to kill the listening thread at the user's will (say via a sto button). I have done this via the Sun's proposed way, by testing a boolean flag in the loop, which is set to false when i wish to kill the thread. The problem with this thing is the following...
Once the thread starts excecuting, it will test the flag, find it true and enter the loop. At some point it will LOCK on the server socket waiting for connection. Unless some client actually connects, it will keep on listening indefinatelly whithought ever bothering to check for the flag again (no matter how many times you set the damn thing to false).
My question is this: Is there any real, non-theoretical, applied way to stop thread in java safely?
Thank you in advance,
Lefty

This was one solution from the socket programming forum, have you tried this??
public Thread MyThread extends Thread{
     boolean active = true;
     public void run(){
          ss.setSoTimeout(90);
          while (active){
               try{
                    serverSocket = ss.accept();
               catch (SocketTimeoutException ste){
               // do nothing
     // interrupt thread
     public void deactivate(){
          active = false;
          // you gotta sleep for a time longer than the
          // accept() timeout to make sure that timeout is finished.
          try{
               sleep(91);
          }catch (InterruptedException ie){
          interrupt();
}

A problem with Threads and MMapi

I am tring to execute a class based on Game canvas.
The problem begin when I try to Play both a MIDI tone and to run an infinit Thread loop.
The MIDI tone "Stammers".
How to over come the problem?
Thanks in advance
Kobi
See Code example below:
import java.io.IOException;
import java.io.InputStream;
import javax.microedition.lcdui.Graphics;
import javax.microedition.lcdui.Image;
import javax.microedition.lcdui.game.GameCanvas;
import javax.microedition.media.Manager;
import javax.microedition.media.MediaException;
import javax.microedition.media.Player;
public class MainScreenCanvas extends GameCanvas implements Runnable {
     private MainMIDlet parent;
     private boolean mTrucking = false;
     Image imgBackgound = null;
     int imgBackgoundX = 0, imgBackgoundY = 0;
     Player player;
     public MainScreenCanvas(MainMIDlet parent)
          super(true);
          this.parent = parent;
          try
               imgBackgound = Image.createImage("/images/area03_bkg0.png");
               imgBackgoundX = this.getWidth() - imgBackgound.getWidth();
               imgBackgoundY = this.getHeight() - imgBackgound.getHeight();
          catch(Exception e)
               System.out.println(e.getMessage());
      * starts thread
     public void start()
          mTrucking = true;
          Thread t = new Thread(this);
          t.start();
      * stops thread
     public void stop()
          mTrucking = false;
     public void play()
          try
               InputStream is = getClass().getResourceAsStream("/sounds/scale.mid");
               player = Manager.createPlayer(is, "audio/midi");
               player.setLoopCount(-1);
               player.prefetch();
               player.start();
          catch(Exception e)
               System.out.println(e.getMessage());
     public void run()
          Graphics g = getGraphics();
          play();
          while (true)
               tick();
               input();
               render(g);
      * responsible for object movements
     private void tick()
      * response to key input
     private void input()
          int keyStates = getKeyStates();
          if ((keyStates & LEFT_PRESSED) != 0)
               imgBackgoundX++;
               if (imgBackgoundX > 0)
                    imgBackgoundX = 0;
          if ((keyStates & RIGHT_PRESSED) != 0)
               imgBackgoundX--;
               if (imgBackgoundX < this.getWidth() - imgBackgound.getWidth())
                    imgBackgoundX = this.getWidth() - imgBackgound.getWidth();
      * Responsible for the drawing
      * @param g
     private void render(Graphics g)
          g.drawImage(imgBackgound, imgBackgoundX, imgBackgoundY, Graphics.TOP | Graphics.LEFT);
          this.flushGraphics();
}

You can also try to provide a greater Priority to your player thread so that it gains the CPU time when ever it needs it and don't harm the playback.
However a loop in a Thread and that to an infinite loop is one kind of very bad programming, 'cuz the loop eats up most of your CPU time which in turn adds up more delays of the execution of other tasks (just as in your case it is the playback). By witting codes bit efficiently and planning out the architectural execution flow of the app before start writing the code helps solve these kind of issues.
You can go through [this simple tutorial|http://oreilly.com/catalog/expjava/excerpt/index.html] about Basics of Java and Threads to know more about threads.
Regds,
SD
N.B. And yes there are more articles and tutorials available but much of them targets the Java SE / EE, but if you want to read them here is [another great one straight from SUN|http://java.sun.com/docs/books/tutorial/essential/concurrency/index.html] .
Edited by: find_suvro@SDN on 7 Nov, 2008 12:00 PM

J2ME problem with threads

Hi all,
I would like to ask you for a help. I need to write a small program at my university. I started to write a midlet which function would be to countdown time for sports activities. I woul like to start a new thread - the one that counts down - and at the same time make the main thread sleep. After the "countdown" thread finishes, the main thread wakes up and waits for user input. The problem is that when the "countdown" thread finishes his work, I've got Uncaught exception java/lang/NullPointerException. error and the midlet halts.
Below you can find the code
import java.lang.*;
import java.util.*;
import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;
public class intervals extends MIDlet implements CommandListener
public Display ekran;
private SweepCanvas sweeper;
private Form rundy;
private TextField round0, round1, round2, round3, round4, round5, round6, round7, round8;
private long czas,x;
private Command exitCommand;
private Command addRound;
private Command delRound;
private Command start;
private TextField repeat;
private Form odliczanie;
private Alert ostrz;
Licznik thread;
String test;
StringItem test1;
int parz,i,j,k;
static int l;
int ilrund;
int ilpowt;
Item sec;
long sec1;
public intervals()
    rundy = new Form("Interwały sportowe");
    exitCommand = new Command("Wyjście", Command.EXIT, 2);
    addRound = new Command("Dodaj","Dodaj rundę", Command.ITEM,1);
    delRound = new Command("Usuń","Usuń ostatnią rundę", Command.ITEM,1);
    start = new Command("Start", Command.ITEM,1);
    odliczanie = new Form("Odliczanie");
    TextField dodaj(TextField kolej)
        kolej=new TextField("Podaj czas (s) rundy "+parz,null, 4, TextField.NUMERIC);//stworzenie nowej instancji do wybierania czasu trwania rundy
        if(rundy.size()==0)
            rundy.insert(rundy.size(),kolej);
            else
                rundy.insert(rundy.size()-1, kolej);
        return kolej;
    void odliczanie(TextField round)
        monitor m=new monitor();
        k=Integer.parseInt(round.getString());
        ekran.setCurrent(odliczanie);
        thread=new Licznik(k,odliczanie);
        thread.start();
        ekran.setCurrent(rundy);
public void startApp()// throws MIDletStateChangeException
    rundy.deleteAll();
    repeat = new TextField("Podaj ilość powtórzeń",null,1,TextField.NUMERIC);
    rundy.addCommand(addRound);
    rundy.addCommand(exitCommand);
    rundy.setCommandListener(this);
    Canvas obrazek = new MyCanvas();
    ekran = Display.getDisplay(this);
    ekran.setCurrent(obrazek);
    czas=System.currentTimeMillis();
    while (System.currentTimeMillis()<czas+1000)
        continue;
    ekran.setCurrent(rundy);
public void pauseApp()
public void destroyApp(boolean unconditional)
    notifyDestroyed();
public void commandAction(Command c, Displayable s)
    if (c == exitCommand)
        destroyApp(false);
        notifyDestroyed();
    else if(c==addRound)
        if(rundy.size()==0)//Sprawdzenie ilości elementów w celu poprawnego wyświetlania liczby rund w formie
            parz=1;
            else
            parz=rundy.size();
        switch(parz)
            case 1:
                round0=dodaj(round0);break;
            case 2:
                round1=dodaj(round1);break;
            case 3:
               round2= dodaj(round2);break;
            case 4:
                round3=dodaj(round3);break;
            case 5:
                round4=dodaj(round4);break;
            default:
                ostrz=new Alert("Uwaga","Maksymalna liczba rund wynosi 9", null, AlertType.INFO);
                ostrz.setTimeout(3000);
                ekran.setCurrent(ostrz);
        if(rundy.size()==1)
            rundy.append(repeat);
            rundy.addCommand(start);
        rundy.addCommand(delRound);
    else if(c==delRound)
        if(rundy.size()!=0)
            rundy.delete(rundy.size()-2);
            if (rundy.size()==1)
                rundy.deleteAll();
            if(rundy.size()==0)
                rundy.removeCommand(delRound);
                rundy.removeCommand(start);
    else if(c==start)
        ilrund=rundy.size()-1;
        if(this.repeat.size()>0)
            ilpowt=Integer.parseInt(this.repeat.getString());
        ekran = Display.getDisplay(this);
        for (i=1; i<=ilpowt;i++)
            odliczanie= new Form("Odliczanie");
             for (j=0;j<ilrund;j++)
                switch(j)
                     case 0:
                         odliczanie(round0);
                         break;
                     case 1:
                         odliczanie(round1);
                         break;
                     case 2:
                         odliczanie(round2);
                         break;
                     case 3:
                         odliczanie(round3);
                         break;
                     case 4:
                         odliczanie(round4);
                         break;
                     case 5:
                         odliczanie(round5);
                         break;
                     case 6:
                         odliczanie(round6);
                         break;
                     case 7:
                         odliczanie(round7);
                         break;
                     case 8:
                         odliczanie(round8);
                         break;
class Licznik extends Thread
    int czas1,k;
    Form forma;
    monitor m;
    public Licznik(int k,Form formap)
        czas1=k;
        forma=formap;
    public synchronized void run()
        while(czas1>0)
            forma.deleteAll();
            forma.append("Czas pozostały (s): "+czas1);
            try{Thread.sleep(1000);} catch(InterruptedException e){e.printStackTrace();}
            czas1--;
        if(czas1<=0)
            m.put();
    }and monitor class
public class monitor
boolean busy=false;
synchronized void get()
    if(!busy)
        try
            wait();
        }catch(InterruptedException e){e.printStackTrace();}
    notify();
synchronized void put()
    if(busy)
        try
        wait();
        }catch(InterruptedException e){e.printStackTrace();}
    busy=true;
    notify();
}Can anybody help me with this?

Groovemaker,
Your Licznik class has a member m of type monitor, which has not been instantiated (in other words is null) hence, when calling m.put() you get NullPointerException. Please also mind, that using Thread.sleep(1000) is not an accurate way of measuring time.
If I may, please use recommended for Java class naming conventions - some of your names use lower case, while other don't which is confusing to the reader.
Daniel

Problem with threads within applet

Hello,
I got an applet, inside this applet I have a singleton, inside this singleton I have a thread.
this thread is running in endless loop.
he is doing something and go to sleep on and on.
the problem is,
when I refresh my IE6 browser I see more than 1 thread.
for debug matter, I did the following things:
inside the thread, sysout every time he goes to sleep.
sysout in the singleton constructor.
sysout in the singleton destructor.
the output goes like this:
when refresh the page, the singleton constructor loading but not every refresh, sometimes I see the constructor output and sometimes I dont.
The thread inside the singleton is giving me the same output, sometime I see more than one thread at a time and sometimes I dont.
The destructor never works (no output there).
I don't understand what is going on.
someone can please shed some light?
thanks.
btw. I am working with JRE 1.1
this is very old and big applet and I can't convert it to something new.

Ooops. sorry!
I did.
     public void start() {
     public void stop() {
     public void destroy() {
          try {
               resetAll();
               Configuration.closeConnection();
               QuoteItem.closeConnection();
          } finally {
               try {
                    super.finalize();
               } catch (Throwable e) {
                    e.printStackTrace();
     }

Problem with Threads and a static variable

I have a problem with the code below. I am yet to make sure that I understand the problem. Correct me if I am wrong please.
Code functionality:
A timer calls SetState every second. It sets the state and sets boolean variable "changed" to true. Then notifies a main process thread to check if the state changed to send a message.
The problem as far I understand is:
Assume the timer Thread calls SetState twice before the main process Thread runs. As a result, "changed" is set to true twice. However, since the main process is blocked twice during the two calls to SetState, when it runs it would have the two SetState timer threads blocked on its synchronized body. It will pass the first one, send the message and set "changed" to false since it was true. Now, it will pass the second thread, but here is the problem, "changed" is already set to false. As a result, it won't send the message even though it is supposed to.
Would you please let me know if my understanding is correct? If so, what would you propose to resolve the problem? Should I call wait some other or should I notify in a different way?
Thanks,
B.D.
Code:
private static volatile boolean bChanged = false;
private static Thread objMainProcess;
   protected static void Init(){
        objMainProcess = new Thread() {
            public void run() {
                while( objMainProcess == Thread.currentThread() ) {
                   GetState();
        objMainProcess.setDaemon( true );
        objMainProcess.start();
    public static void initStatusTimer(){
        if(objTimer == null)
             objTimer = new javax.swing.Timer( 1000, new java.awt.event.ActionListener(){
                public void actionPerformed( java.awt.event.ActionEvent evt){
                          SetState();
    private static void SetState(){
        if( objMainProcess == null ) return;
        synchronized( objMainProcess ) {
            bChanged = true;
            try{
                objMainProcess.notify();
            }catch( IllegalMonitorStateException e ) {}
    private static boolean GetState() {
        if( objMainProcess == null ) return false;
        synchronized( objMainProcess ) {
            if( bChanged) {
                SendMessage();
                bChanged = false;
                return true;
            try {
                objMainProcess.wait();
            }catch( InterruptedException e ) {}
            return false;
    }

Thanks DrClap for your reply. Everything you said is right. It is not easy to make them alternate since SetState() could be called from different places where the state could be anything else but a status message. Like a GREETING message for example. It is a handshaking message but not a status message.
Again as you said, There is a reason I can't call sendMessage() inside setState().
The only way I was able to do it is by having a counter of the number of notifies that have been called. Every time notify() is called a counter is incremented. Now instead of just checking if "changed" flag is true, I also check if notify counter is greater than zero. If both true, I send the message. If "changed" flag is false, I check again if the notify counter is greater than zero, I send the message. This way it works, but it is kind of a patch than a good design fix. I am yet to find a good solution.
Thanks,
B.D.

Problem with threads running javaw

Hi,
Having a problem with multi thread programming using client server sockets. The program works find when starting the the application in a console using java muti.java , but when using javaw multi.java the program doesnt die and have to kill it in the task manager. The program doesnt display any of my gui error messages either when the server disconnect the client. all works find in a console. any advice on this as I havent been able to understand why this is happening? any comment would be appreciated.
troy.

troy,
Try and post a minimum code sample of your app which
does not work.
When using javaw, make sure you redirect the standard
error and standard output streams to file.
Graeme.Hi Graeme,
I dont understand what you mean by redirection to file? some of my code below.
The code works fine under a console, code is supposed to exit when the client (the other server )disconnects. the problem is that but the clientworker side of the code still works. which under console it doesnt.
public class Server{
ServerSocket aServerSocket;
Socket dianosticsSocket;
Socket nPortExpress;
ClientListener aClientListener;
LinkedList queue = new LinkedList();
int port = 0;
int clientPort = 0;
String clientName = null;
boolean serverAlive = true;
* Server constructor generates a server
* Socket and then starts a client threads.
* @param aPort      socket port of local machine.
public Server(int aPort, String aClientName, int aClientPort){
port = aPort;
clientName = aClientName;
clientPort = aClientPort;
try{
// create a new thread
aServerSocket = new ServerSocket(port) ;
// connect to the nPortExpress
aClientListener = new ClientListener(InetAddress.getByName(clientName), clientPort, queue,this);
// aClientListener.setDaemon(true);
aClientListener.start();
// start a dianostic port
DiagnosticsServer aDiagnosticsServer = new DiagnosticsServer(port,queue,aClientListener);
// System.out.println("Server is running on port " + port + "...");
// System.out.println("Connect to nPort");
catch(Exception e)
// System.out.println("ERROR: Server port " + port + " not available");
JOptionPane.showMessageDialog(null, (e.toString()),"ERROR: Server port " + port + " not available", JOptionPane.ERROR_MESSAGE);
serverAlive = false;
System.exit(1);
while(serverAlive&&aClientListener.hostSocket.isConnected()){
try{
// connect the client
Socket aClient = aServerSocket.accept();
//System.out.println("open client connection");
//System.out.println("client local: "+ aClient.getLocalAddress().toString());
// System.out.println("client localport: "+ aClient.getLocalPort());
// System.out.println("client : "+ aClient.getInetAddress().toString());
// System.out.println("client port: "+ aClient.getLocalPort());
// make a new client thread
ClientWorker clientThread = new ClientWorker(aClient, queue, aClientListener, false);
// start thread
clientThread.start();
catch(Exception e)
//System.out.println("ERROR: Client connection failure");
JOptionPane.showMessageDialog(null, (e.toString()),"ERROR: Client connection failure", JOptionPane.ERROR_MESSAGE);
}// end while
} // end constructor Server
void serverExit(){
     JOptionPane.showMessageDialog(null, "Server ","ERROR: nPort Failure", JOptionPane.ERROR_MESSAGE);
     System.exit(1);
}// end class Server
*** connect to another server
public class ClientListener extends Thread{
InetAddress hostName;
int hostPort;
Socket hostSocket;
BufferedReader in;
PrintWriter out;
boolean loggedIn;
LinkedList queue;      // reference to Server queue
Server serverRef; // reference to main server
* ClientListener connects to the host server.
* @param aHostName is the name of the host eg server name or IP address.
* @param aHostPort is a port number of the host.
* @param aLoginName is the users login name.
public ClientListener(InetAddress aHostName, int aHostPort,LinkedList aQueue,Server aServer)      // reference to Server queue)
hostName = aHostName;
hostPort = aHostPort;
queue = aQueue;
serverRef = aServer;
// connect to the server
try{
hostSocket = new Socket(hostName, hostPort);
catch(IOException e){
//System.out.println("ERROR: Connection Host Failed");
JOptionPane.showMessageDialog(null, (e.toString()),"ERROR: Connection to nPort Failed", JOptionPane.ERROR_MESSAGE);
System.exit(0);
} // end constructor ClientListener
** multi client connection server
ClientWorker(Socket aSocket,LinkedList aQueue, ClientListener aClientListener, boolean diagnostics){
queue = aQueue;
addToQueue(this);
client = aSocket;
clientRef = aClientListener;
aDiagnostic = diagnostics;
} // end constructor ClientWorker
* run method is the main loop of the server program
* in change of handle new client connection as well
* as handle all messages and errors.
public void run(){
boolean alive = true;
String aSubString = "";
in = null;
out = null;
loginName = "";
loggedIn = false;
while (alive && client.isConnected()&& clientRef.hostSocket.isConnected()){
try{
in = new BufferedReader(new InputStreamReader(client.getInputStream()));
out = new PrintWriter(new OutputStreamWriter(client.getOutputStream()));
if(aDiagnostic){
out.println("WELCOME to diagnostics");
broadCastDia("Connect : diagnostics "+client.getInetAddress().toString());
out.flush();
else {
out.println("WELCOME to Troy's Server");
broadCastDia("Connect : client "+client.getInetAddress().toString());
     out.flush();
String line;
while(((line = in.readLine())!= null)){
StringTokenizer aStringToken = new StringTokenizer(line, " ");
if(!aDiagnostic){
broadCastDia(line);
clientRef.sendMessage(line); // send mesage out to netExpress
out.println(line);
out.flush();
else{
if(line.equals("GETIPS"))
getIPs();
else{
clientRef.sendMessage(line); // send mesage out to netExpress
out.println(line);
out.flush();
} // end while
catch(Exception e){
// System.out.println("ERROR:Client Connection reset");
                         JOptionPane.showMessageDialog(null, (e.toString()),"ERROR:Client Connection reset", JOptionPane.ERROR_MESSAGE);
try{
if(aDiagnostic){
broadCastDia("Disconnect : diagnostics "+client.getInetAddress().toString());
out.flush();
else {
broadCastDia("Disconnect : client "+client.getInetAddress().toString());
     out.flush();
// close the buffers and connection;
in.close();
out.close();
client.close();
// System.out.println("out");
// remove from list
removeThreadQueue(this);
alive = false;
catch(Exception e){
// System.out.println("ERROR: Client Connection reset failure");
JOptionPane.showMessageDialog(null, (e.toString()),"ERROR: Client Connection reset failure", JOptionPane.ERROR_MESSAGE);
}// end while
} // end method run
* method run - Generates io stream for communicating with the server and
* starts the client gui. Run also parses the input commands from the server.
public void run(){
boolean alive = true;
try{
// begin to life the gui
// aGuiClient = new ClientGui(hostName.getHostName(), hostPort, loginName, this);
// aGuiClient.show();
in = new BufferedReader(new InputStreamReader(hostSocket.getInputStream()));
out = new PrintWriter(new OutputStreamWriter(hostSocket.getOutputStream()));
while (alive && hostSocket.isConnected()){
String line;
while(((line = in.readLine())!= null)){
System.out.println(line);
broadCast(line);
} // end while
} // end while
catch(Exception e){
//     System.out.println("ERRORa Connection to host reset");
JOptionPane.showMessageDialog(null, (e.toString()),"ERROR: Connection to nPort reset", JOptionPane.ERROR_MESSAGE);
try{
hostSocket.close();
     }catch(Exception a){
     JOptionPane.showMessageDialog(null, (a.toString()),"ERROR: Exception", JOptionPane.ERROR_MESSAGE);
alive = false;
System.exit(1);
} // end method run

Problem with Threads and "plase wait..."-Window

Hi everyone,
I have a problem that I'm not able to solve in any way... I have a time-consuming task (a file decryption) which I execute in a separate thread; I've used the SwingWorker class, like suggested by sun-tutorial, and it works right. The problem is that I have to wait that the decryption have finished before continuing with program-execution. Therefore I would like to display a "please wait"-window while the task runs. I've tryed all the possible ways I know but the problem is always the same: the waitWindow is displayed empty, the bounds are painted but the contents no; it's only painted when the decrypt-task has finished. Please help me, I have no more resources....
decrypt-file code:
public class DecryptFile {
private String cryptedFileNameAndPath;
private ByteArrayInputStream resultStream = null;
// need for progress
private int lengthOfTask;
private int current = -1;
private String statMessage;
public DecryptFile(String encZipFileNameAndPath) {
    cryptedFileNameAndPath = encZipFileNameAndPath;
    //Compute length of task...
    // 0 for indeterminate
    lengthOfTask = 0;
public ByteArrayInputStream getDecryptedInputStream() {
    return this.resultStream;
   * Called from ProgressBarDemo to start the task.
public void go() {
    current = -1;
    final SwingWorker worker = new SwingWorker() {
      public Object construct() {
        return new ActualTask();
    worker.start();
   * Called from ProgressBarDemo to find out how much work needs
   * to be done.
public int getLengthOfTask() {
    return lengthOfTask;
   * Called from ProgressBarDemo to find out how much has been done.
public int getCurrent() {
    return current;
public void stop() {
    current = lengthOfTask;
   * Called from ProgressBarDemo to find out if the task has completed.
public boolean done() {
    if (current >= lengthOfTask)
      return true;
    else
      return false;
public String getMessage() {
    return statMessage;
   * The actual long running task. This runs in a SwingWorker thread.
class ActualTask {
    ActualTask () {
      current = -1;
      statMessage = "";
      resultStream = AIUtil.getInputStreamFromEncZip(cryptedFileNameAndPath); //here the decryption happens
      current = 0;
      statMessage = "";
}The code that calls decryption and displays waitWindow
      final WaitSplash wS = new WaitSplash("Please wait...");
      final DecryptFile cryptedTemplate = new DecryptFile (this.templateFile);
      cryptedTemplate.go();
      while (! cryptedTemplate.done()) {
        try {
          wait();
        } catch (Exception e) { }
      this.templateInputStream = cryptedTemplate.getDecryptedInputStream();
      wS.close();Thanks, thanks, thanks in advance!
Edoardo

Maybe you can try setting the priority of the long-running thread to be lower? so that the UI will be more responsive...

Problem with threads in j2me

im using jdk 1.6 with java wtk 2.1
ya i know..
2.1 is a jdk1.4 source
but im using souce as 1.4 during compiliation so thats not the prob
this is my code
package org.learn;
import javax.microedition.midlet.MIDlet;
import javax.microedition.lcdui.Alert;
import javax.microedition.lcdui.Display;
public class thtest extends MIDlet
Thread t;
public void startApp()
Alert a=new Alert("hello");
a.setString("hello");
Alert b=new Alert("world");
b.setString("world");
Display d = Display.getDisplay(this );
d.setCurrent(a);
t=Thread.currentThread();
try{
t.sleep(10000);
catch (Exception e){}
d.setCurrent(b);
public void pauseApp()
public void destroyApp(boolean unconditional)
its just supposed to pause between the alerts using threads
however when i run it using the wtk, the emulator run properly but when i launch the app, it stops executing giving me this:
"Error verifying method org/learn/thtest startApp()V
Approximate bytecode offset 49: Inconsistent or missing stackmap at target
%the stack info%
Execution completed.
437782 bytecodes executed
9 thread switches
486 classes in the system (including system classes)
2506 dynamic objects allocated (73832 bytes)
2 garbage collections (60652 bytes collected)
Execution completed.
437782 bytecodes executed
9 thread switches
486 classes in the system (including system classes)
ALERT: java/lang/VerifyError: org/learn/thtest.
2506 dynamic objects allocated (73832 bytes)
2 garbage collections (60652 bytes collected)
please can someone help me out with this, is it an error on my part or do i have to set some option.

Hi gandalf123,
First, Thread.sleep is a static method, so you don't need to create a Thread object to use it.
I think the problem is due to the fact you don't preverify your midlet.
More over, you don't need to double post your question.

Problem with threads and camera.

Hi everybody!
I've a problem with taking snapshot.
I would like to display a loading screen after it take snapshot ( sometimes i
have to wait few seconds after i took snapshot. Propably photo is being taken in time where i have to wait).
I was trying to use threads but i didn't succeed.
I made this code:
display.setCurrent(perform);
        new Thread(new Runnable(){
            public void run() {
                while((!performing.isShown()) && (backgroundCamera.isShown())){
                    Thread.yield();
                notifyAll();
        }).start();
        new Thread(new Runnable(){
            public void run() {
                try {
                    this.wait();
                } catch(Exception e) {
                    exceptionHandler(e);
                photo = camera.snapshot();
                display.setCurrent(displayPhoto);
        }).start();This code is sometimes showing performing screen but sometimes no.
I don't know why. In my opinion performing.isShown() method isn't working correctly.
Does anyone have some idea how to use threads here?

Hi,
I've finally managed to work this fine.
The code:
       Object o = new Object();
       display.setCurrent(perform);
        new Thread(new Runnable(){
            public void run() {
                while(!performing.isShown()){
                    Thread.yield();
               synchronized(o) {
                  o.notify();
        }).start();
        new Thread(new Runnable(){
            public void run() {
                try {
                    synchronized(o) {
                       o.wait(1);
                } catch(Exception e) {
                    exceptionHandler(e);
                photo = camera.snapshot();
                display.setCurrent(displayPhoto);
        }).start();

Problem with threads and graphics

I have a thread that chooses paths for a Travelling salesman problem, it then calls a TSPdraw class and passes it the path, which the class then draws. the problem is when i have two threads it creates two windows but only draws a path in one of them. any ideas where i`m going wrong

Are you using swing components? Swing isn't threadsafe. If you have multiple threads that want to update your UI you need to use the SwingUtilities.invokeLater(...)or invokeAndWait(...). There is a page in the swing tutorial about this at: http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html

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