The JFrame class

Why does the JFrame class implement the Accessible interface in its code? Isn't the Accessible interface already inherited when the JFrame extended to the Window class?
I'm fairly new to Java and have been going through the documentation on the APIs and noticed this. Haven't seen if it is elsewhere.
Thanks to whoever provides input.

Because Sun do not exclusively employ perfect developers, basically. Looking at the source for both JFrame and Window, you'll see they were written by different programmers. The pair that developed JFrame possibly didn't realise that the class implicitly already implemented Accessible. Notice how Frame implements MenuContainer, which a superclass - Component - already does.
The JDK isn't a particularly well-designed lump of code, to be honest. It's full of examples of how not to do things, poor OO design and silly mistakes like this. Don't make the mistake of thinking because it's a Sun release, it must show The Right Way ? to do things, it doesn't

Similar Messages

Can not add a picture to the JFrame from an ActionListener class

As topic says, I can not add a picture to the JFrame from an ActionListener class which is a class inside the JFrame class.
I have a Map.java class where I load an image with ImageIcon chosen with JFileChooser.
I my window class (main class), I have following:
class OpenImage_Listener implements ActionListener
     public void actionPerformed(ActionEvent e)
          int ans = open.showOpenDialog(MainProgram.this);     // "open" is the JFileChooser reference
          if(ans == open.APPROVE_OPTION)
               File file = open.getSelectedFile();
               MainProgram.this.add(new Map(file.getName()), BorderLayout.CENTER);     // this line does not work - it does not add the choosen picture on the window,
                        //but if I add the picture outside this listener class and inside the MainProgram constructor, the picture apperas, but then I cannot use the JFileChooser.
                        showMessageDialog(MainProgram.this, fil.getName() ,"It works", INFORMATION_MESSAGE); // this popup works, and thereby the ActionListener also works.
}So why can�t I add a picture to the window from the above listener class?

The SSCCE:
Ok, I think I solved it with the picture, but now I cannot add new components after adding the picture.
Look at the comment in the actionlistener class:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.*;
public class Test extends JFrame{
     JButton b = new JButton("Open");
     JFileChooser jfc = new JFileChooser(System.getProperty("user.dir"));
     Picture pane;
     Test(){
          super("Main Program");
          setLayout(new BorderLayout());
          JPanel north = new JPanel();
          add(north, BorderLayout.NORTH);
          north.add(b);
          b.addActionListener(new Listener());
          setVisible(true);
          setSize(500,500);
          pane = new Picture("");
          add(pane, BorderLayout.CENTER);
     class Listener implements ActionListener {
          public void actionPerformed(ActionEvent e){
               int ans = jfc.showOpenDialog(Test.this);
               if(ans == jfc.APPROVE_OPTION)
                    File file = jfc.getSelectedFile();
                    Test.this.add(new Picture(file.getName()), BorderLayout.CENTER);
                    pane.add(new JButton("NEW BUTTON")); // Why does this button not appear on the window???
                    pane.repaint();
                    pane.revalidate();
     public static void main(String[] args)
          Test t = new Test();
class Picture extends JPanel
     Image pic;
     String filename;
     Picture(String filename)
          setLayout(null);
          this.filename = filename;
          pic = Toolkit.getDefaultToolkit().getImage(filename);
        protected void paintComponent(Graphics g)
            super.paintComponent(g);
            g.drawImage(pic,0,0,getWidth(),getHeight(),this);
            revalidate();
}

Problem with setContentPane() in JFrame class

I recently discovered a problem with the setContentPane method in the JFrame class. When I use setContentPane(Container ..), the previously existing contentPane remains in the stack. I have tried nullifying getContentPane(), and all manner of things, but, each time I use setContentPane, I have another instance of a JPanel in the stack.
I'm using code similar to setContentPane(new CustomJPanel()); and each time the user changes screens, and a similar call to that is made, the old CustomJPanel instance remains in the stack. Can anyone suggest a way around this? On their own the panels do not take up very much memory, but after several hours of usage, they will build up.

I tried what you suggested; it only resulted in a huge performance decrease. The problem with memory allocation is still there.
Here is the method I use to switch screens in my app:
public static void changeScreen (JPanel panel){
          try{
               appFrame.setTitle("Wordinary : \""+getTitle()+"\"");
               appFrame.setContentPane(panel);
               appFrame.setSize(appFrame.getContentPane().getPreferredSize());
               appFrame.getContentPane().setBackground(backColour);
               for (int i = 0; i < appFrame.getContentPane().getComponents().length; i++)
                    appFrame.getContentPane().getComponents().setForeground(textColour);
               //System.out.println("Background colour set to "+backColour+" text colour set to "+textColour);
               appFrame.validate();
          catch (Exception e){
               //System.out.println("change");
               e.printStackTrace();
And it is called like this:
changeScreen(new AddWordPanel());The instantiation of the new instance is what is causing the memory problems, but I can't think of a way around it.

Need help:JPanel not being displayed in the JFrame

Hello,
I have a class called ConstructRoom.java which extends JFrame and another class called DimensionsPanel.java which extends JPanel. In the ConstructRoom class I use the following theContainer.add(new DimensionsPanel());, so I can display my JPanel. Well I get the JFrame but no JPanel. When the this call is made the DimensionsPanel.java code is cycled through, Where has my JPanel gone to?
If I change the DimensionPanel.java extend JFrame and add the the JFrame code. Then I get the JFrame and the JPanel.
Whats going on here?
Thanks

I made some of the changes with no luck. Here is some of the code:
---------from ConstructRoom.java--------
//Imports
public class ConstructRoom extends JFrame
//----Member objects and varibles
private static String theTitle; //Varible for title of frame
private JFrame theFrame; //Object for the JFrame
// ----------------------------------------------------------- ConstructRoom
public ConstructRoom(String theTitle)
super(theTitle); //JFrame super class
theFrame = new JFrame("My frame");
Container theContainer = theFrame.getContentPane(); //Frame container
theContainer.setLayout(new FlowLayout());
theContainer.add(new DimensionsPanel());
theFrame.pack();
theFrame.setBounds(10,10,400, 400);
theFrame.addWindowListener(new WindowHandler());
theFrame.setVisible(true);
}//end ConstructRoom(String theTitle)
// -------------------------------------------------------------------- main
public static void main(String args[])
ConstructRoom theRoom = new ConstructRoom(theTitle);
}//end main(String args[])
//----WindowHander
}//end class ConstructRoom extends JFrame
--------from DimensionsPanel.java
//Imports
public class DimensionsPanel extends JPanel
//----Member objects and varibles
private JPanel dimensionsPanel; //The main panel to hold all info
private Box panelBox; //Box for all boxes which is added to the JPanel
private Box furnListBox; //Box for all related items of the furnList
private Box dimensionsBox; //Box for all dimensions (x, y, z)
private Box xFieldBox; //Box for all related items of the xField
private Box yFieldBox; //Box for related items of the yField
private Box zFieldBox; //Box for related items of the zField
private Box buttonsBox; //Box for all buttons
private Box clearBox; //Box for related clear button items
private Box buildBox; //Box for related build button items
private JLabel furnListLabel; //Label for the furnList comboBox
private JLabel xFieldLabel; //Label for the xField
private JLabel yFieldLabel; //Label for yField
private JLabel zFieldLabel; //Label for zField
private JTextField xField; //Text field to enter the x dimension
private JTextField yField; //Text field to enter the y dimension
private JTextField zField; //Text field to enter the z dimension
private JComboBox furnList; //List of selectable furniture objects
private JButton clearButton; //Clear button
private JButton buildButton; //Build button
// --------------------------------------------------------- DimensionsPanel
public DimensionsPanel()
//----Setting up dimensions panel
dimensionsPanel = new JPanel();
dimensionsPanel.setLayout(new BorderLayout());
dimensionsPanel.setPreferredSize(new Dimension(150,150));
dimensionsPanel.setBorder(new TitledBorder(new EtchedBorder(),
"Select Furniture and Enter Dimensions"));
//----Initializing GUI components
furnListLabel = new JLabel("Select from list ");
furnList = new JComboBox();
xFieldLabel = new JLabel("Enter Width ");
xField = new JTextField();
yFieldLabel = new JLabel("Enter Height ");
yField = new JTextField();
zFieldLabel = new JLabel("Enter Depth ");
zField = new JTextField();
buildButton = new JButton("Build Object");
clearButton = new JButton("Clear Object");
//-----Setting up the combo box and adding items
furnList.addActionListener(new ComboProcessor());
furnList.addItem(" "); //Default item
furnList.addItem("Color Cube");
furnList.setMaximumRowCount(6); //Max number of items before scrolling
furnList.setSelectedItem(" "); //Set initial to default item
//--Add the furnList to its box for placement in the JPanel
furnListBox = Box.createHorizontalBox();
furnListBox.add(Box.createHorizontalStrut(5));
furnListBox.add(furnListLabel); //Adding the combo box label
furnListBox.add(furnList); //Adding the combo box
furnListBox.add(Box.createHorizontalStrut(5)); //Spacing
//-------------------------------- Start Dimensions Components
//----Setting up the xField
xField.setEnabled(false); //Disabled at start
xField.setFocusTraversalKeysEnabled(false); //Disabling the Tab Key
//----Adding the event listeners
xField.addActionListener(new XTextProcessor()); //Enter Key
xField.addMouseListener(new ClickProcessor()); //Mouse Click
//--Add the xField to its box for placement in the dimensionsBox
xFieldBox = Box.createHorizontalBox();
xFieldBox.add(Box.createHorizontalStrut(10)); //Spacing
xFieldBox.add(Box.createGlue()); //Take up extra space
xFieldBox.add(xFieldLabel); //Adding the text field label
xFieldBox.add(xField); //Adding the text field
xFieldBox.add(Box.createHorizontalStrut(100)); //Spacing
//----Setting up the yfield
yField.setEnabled(false); //Disabled at start
yField.setFocusTraversalKeysEnabled(false); //Disabling TAB KEY
//----Adding the event listeners
yField.addActionListener(new YTextProcessor()); //Enter Key
yField.addMouseListener(new ClickProcessor()); //Mouse Click
//--Add the yField to its box for placement in the dimensionsBox
yFieldBox = Box.createHorizontalBox();
yFieldBox.add(Box.createHorizontalStrut(10)); //Spacing
yFieldBox.add(Box.createGlue()); //Take up extra space
yFieldBox.add(yFieldLabel); //Adding the text field label
yFieldBox.add(yField); //Adding the text field
yFieldBox.add(Box.createHorizontalStrut(100)); //Spacing
//----Setting up the zfield
zField.setEnabled(false); //Disabled at start
zField.setFocusTraversalKeysEnabled(false); //Disabling TAB KEY
//----Adding the event listeners
zField.addActionListener(new ZTextProcessor()); //Enter Key
zField.addMouseListener(new ClickProcessor()); //Mouse Click
//--Add the zField to its box for placement in the dimensionsBox
zFieldBox = Box.createHorizontalBox();
zFieldBox.add(Box.createHorizontalStrut(10)); //Spacing
zFieldBox.add(Box.createGlue()); //Take up extra space
zFieldBox.add(zFieldLabel); //Adding the text field label
zFieldBox.add(zField); //Adding the text field
zFieldBox.add(Box.createHorizontalStrut(100)); //Spacing
//----Adding all dimension components to the dimensionsBox
dimensionsBox = Box.createVerticalBox();
dimensionsBox.add(xFieldBox); //Adding the xFieldBox
dimensionsBox.add(Box.createVerticalStrut(10)); //Spacing
dimensionsBox.add(yFieldBox); //Adding the yFieldBox
dimensionsBox.add(Box.createVerticalStrut(10)); //Spacing
dimensionsBox.add(zFieldBox); //Adding the zFieldBox
//-------------------------------- End Dimension Components
//----Setting up the clearButton
clearButton.setEnabled(false); //Disabled at start
//----Adding the event listener
clearButton.addActionListener(new ClearProcessor());
//--Add the clear button to its box for placement
clearBox = Box.createHorizontalBox();
clearBox.add(Box.createHorizontalStrut(5)); //Spacing
clearBox.add(clearButton); //Adding the clearButton
//----Setting up the buildButton
buildButton.setEnabled(false); //Disabled at start
//--Add the action listener here
buildBox = Box.createHorizontalBox();
buildBox.add(buildButton); //Adding the buildButton
buildBox.add(Box.createHorizontalStrut(5)); //Spacing
//----Adding both buttons the buttonsBox
buttonsBox = Box.createHorizontalBox();
buttonsBox.add(clearBox); //Adding the clearBox
buttonsBox.add(Box.createHorizontalStrut(10)); //Spacing
buttonsBox.add(buildBox); //Adding the buildBox
//----Create the JPanel (dimensionsPanel)
//--Creating the main box to be added to the JPanel
panelBox = Box.createVerticalBox();
panelBox.add(furnListBox); //Adding the furnListBox components
panelBox.add(Box.createVerticalStrut(10)); //Spacing
panelBox.add(dimensionsBox); //Adding the dimensionBox components
panelBox.add(Box.createVerticalStrut(10)); //Spacing
panelBox.add(buttonsBox); //Adding the buttonsBox components
panelBox.add(Box.createVerticalStrut(10)); //Spacing
dimensionsPanel.add(panelBox); //Adding all components to the JPanel
System.out.println("end dimensionpanel");
}//end DimensionsPanel()
//------ActionListeners
}//end class DimensionsPanel extends JPanel

How to use the Rectangle class to draw an image and center it in a JPanel

I sent an earlier post on how to center an image in a JPanel using the Rectangle class. I was asked to send an executable code which will show the malfunction. The code below is an executable code and a small part of a very big project. To simplifiy things, it is just a JFrame and a JPanel with an open dialog. Once executed the JFrame and the FileDialog will open. You can then navigate to a .gif or a .jpg picture and open it. What I want is for the picture to be centered in the middle of the JPanel and not the upper left corner. It is also important to stress that, I am usinig the Rectangle class to draw the Image. The region of interest is where the rectangle is created. In the constructor of the CenterRect class, I initialize the Rectangle class. Then I use paintComponent in the CenterRect class to draw the Image. The other classes are just support classes. The MyImage class is an extended image class which also has a draw() method. Any assistance in getting the Rectangle to show at the center of the JPanel without affecting the size and shape of the image will be greatly appreciated.
I have divided the code into three parts. They are all supposed to be on one file in order to execute.
import java.awt.*;
import java.awt.image.*;
import javax.swing.*;
public class CenterRect extends JPanel {
    public static Rectangle srcRect;
    Insets insets = null;
    Image image;
    MyImage imp;
    private double magnification;
    private int dstWidth, dstHeight;
    public CenterRect(MyImage imp){
        insets = getInsets();
        this.imp = imp;
        int width = imp.getWidth();
        int height = imp.getHeight();
        ImagePanel.init();
        srcRect = new Rectangle(0,0, width, height);
        srcRect.setLocation(0,0);
        setDrawingSize(width, height);
        magnification = 1.0;
    public void setDrawingSize(int width, int height) {
        dstWidth = width;
        dstHeight = height;
        setSize(dstWidth, dstHeight);
    public void paintComponent(Graphics g) {
        Image img = imp.getImage();
     try {
            if (img!=null)
                g.drawImage(img,0,0, (int)(srcRect.width*magnification), (int)(srcRect.height*magnification),
          srcRect.x, srcRect.y, srcRect.x+srcRect.width, srcRect.y+srcRect.height, null);
        catch(OutOfMemoryError e) {e.printStackTrace();}
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new Opener().openImage();
class Opener{
    private String dir;
    private String name;
    private static String defaultDirectory;
    JFrame parent;
    public Opener() {
        initComponents();
     public void initComponents(){
        parent = new JFrame();
        parent.setContentPane(ImagePanel.panel);
        parent.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
        parent.setExtendedState(JFrame.MAXIMIZED_BOTH);
        parent.setVisible(true);
    public void openDialog(String title, String path){
        if (path==null || path.equals("")) {
            FileDialog fd = new FileDialog(parent, title);
            defaultDirectory = "dir.image";
            if (defaultDirectory!=null)
                fd.setDirectory(defaultDirectory);
            fd.setVisible(true);
            name = fd.getFile();
            if (name!=null) {
                dir = fd.getDirectory();
                defaultDirectory = dir;
            fd.dispose();
            if (parent==null)
                return;
        } else {
            int i = path.lastIndexOf('/');
            if (i==-1)
                i = path.lastIndexOf('\\');
            if (i>0) {
                dir = path.substring(0, i+1);
                name = path.substring(i+1);
            } else {
                dir = "";
                name = path;
    public MyImage openImage(String directory, String name) {
        MyImage imp = openJpegOrGif(dir, name);
        return imp;
    public void openImage() {
        openDialog("Open...", "");
        String directory = dir;
        String name = this.name;
        if (name==null)
            return;
        MyImage imp = openImage(directory, name);
        if (imp!=null) imp.show();
    MyImage openJpegOrGif(String dir, String name) {
            MyImage imp = null;
            Image img = Toolkit.getDefaultToolkit().getImage(dir+name);
            if (img!=null) {
                imp = new MyImage(name, img);
                FileInfo fi = new FileInfo();
                fi.fileFormat = fi.GIF_OR_JPG;
                fi.fileName = name;
                fi.directory = dir;
                imp.setFileInfo(fi);
            return imp;
}

This is the second part. It is a continuation of the first part. They are all supposed to be on one file.
class MyImage implements ImageObserver{
    private int imageUpdateY, imageUpdateW,width,height;
    private boolean imageLoaded;
    private static int currentID = -1;
    private int ID;
    private static Component comp;
    protected ImageProcessor ip;
    private String title;
    protected Image img;
    private static int xbase = -1;
    private static int ybase,xloc,yloc;
    private static int count = 0;
    private static final int XINC = 8;
    private static final int YINC = 12;
    private int originalScale = 1;
    private FileInfo fileInfo;
    ImagePanel win;
    /** Constructs an ImagePlus from an AWT Image. The first argument
     * will be used as the title of the window that displays the image. */
    public MyImage(String title, Image img) {
        this.title = title;
         ID = --currentID;
        if (img!=null)
            setImage(img);
    public boolean imageUpdate(Image img, int flags, int x, int y, int w, int h) {
         imageUpdateY = y;
         imageUpdateW = w;
         imageLoaded = (flags & (ALLBITS|FRAMEBITS|ABORT)) != 0;
     return !imageLoaded;
    public int getWidth() {
         return width;
    public int getHeight() {
         return height;
    /** Replaces the ImageProcessor, if any, with the one specified.
     * Set 'title' to null to leave the image title unchanged. */
    public void setProcessor(String title, ImageProcessor ip) {
        if (title!=null) this.title = title;
        this.ip = ip;
        img = ip.createImage();
        boolean newSize = width!=ip.getWidth() || height!=ip.getHeight();
     width = ip.getWidth();
     height = ip.getHeight();
     if (win!=null && newSize) {
            win = new ImagePanel(this);
    public void draw(){
        CenterRect ic = null;
        win = new ImagePanel(this);
        if (win!=null){
            win.addIC(this);
            win.getCanvas().repaint();
            ic = win .getCanvas();
            win.panel.add(ic);
            int width = win.imp.getWidth();
            int height = win.imp.getHeight();
            Point ijLoc = new Point(10,32);
            if (xbase==-1) {
                xbase = 5;
                ybase = ijLoc.y;
                xloc = xbase;
                yloc = ybase;
            if ((xloc+width)>ijLoc.x && yloc<(ybase+20))
                yloc = ybase+20;
                int x = xloc;
                int y = yloc;
                xloc += XINC;
                yloc += YINC;
                Dimension screen = Toolkit.getDefaultToolkit().getScreenSize();
                count++;
                if (count%6==0) {
                    xloc = xbase;
                    yloc = ybase;
                int scale = 1;
                while (xbase+XINC*4+width/scale>screen.width || ybase+YINC*4+height/scale>screen.height)
                    if (scale>1) {
               originalScale = scale;
               ic.setDrawingSize(width/scale, height/scale);
    /** Returns the current AWT image. */
    public Image getImage() {
        if (img==null && ip!=null)
            img = ip.createImage();
        return img;
    /** Replaces the AWT image, if any, with the one specified. */
    public void setImage(Image img) {
        waitForImage(img);
        this.img = img;
        JPanel panel = ImagePanel.panel;
        width = img.getWidth(panel);
        height = img.getHeight(panel);
        ip = null;
    /** Opens a window to display this image and clears the status bar. */
    public void show() {
        show("");
    /** Opens a window to display this image and displays
     * 'statusMessage' in the status bar. */
    public void show(String statusMessage) {
        if (img==null && ip!=null){
            img = ip.createImage();
        if ((img!=null) && (width>=0) && (height>=0)) {
            win = new ImagePanel(this);
            draw();
    private void waitForImage(Image img) {
    if (comp==null) {
        comp = ImagePanel.panel;
        if (comp==null)
            comp = new JPanel();
    imageLoaded = false;
    if (!comp.prepareImage(img, this)) {
        double progress;
        while (!imageLoaded) {
            if (imageUpdateW>1) {
                progress = (double)imageUpdateY/imageUpdateW;
                if (!(progress<1.0)) {
                    progress = 1.0 - (progress-1.0);
                    if (progress<0.0) progress = 0.9;
public void setFileInfo(FileInfo fi) {
    fi.pixels = null;
    fileInfo = fi;
}

Problem with JFrame class.

To risolve my problem i need for few diferent frame
( for esample in one i put JTextFild that take the user input, in a nother one i need for program output ) . But, th problem is, all my frames using the same object.
If i construct diferent JFrame window class i have problem that i don't acess in the same object from all the window. And if i dont use a object, i have static acess .
I risolve the problem with 1 JFrame class with diferent constructors, but i wont a diferent way to risolve my problem, because there are few windows.
Help me.....

Make the class that extends JFrame an inner class of the the main class. You can then access all members of the outer class.

How to print the JFrame In The Center Of The Page?

hi there in the following code iam trying to print a JFrame
but the frame appear in the printed page at the top left
and i want it to appear in the top center of the page
how to do that?
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.print.*;
class PrintUIWindow implements Printable, ActionListener {
    JFrame frameToPrint;
    public int print(Graphics g, PageFormat pf, int page) throws
                                                        PrinterException {
        if (page > 0) {
            return NO_SUCH_PAGE;
        Graphics2D g2d = (Graphics2D)g;
        g2d.translate(pf.getImageableX(), pf.getImageableY()-55);
        frameToPrint.print(g);
        return PAGE_EXISTS;
    public void actionPerformed(ActionEvent e) {
         PrinterJob job = PrinterJob.getPrinterJob();
         job.setPrintable(this);
         boolean ok = job.printDialog();
         if (ok) {
             try {
                  job.print();
             } catch (PrinterException ex) {
    public PrintUIWindow(JFrame f) {
        frameToPrint = f;
    public static void main(String args[]) {
        UIManager.put("swing.boldMetal", Boolean.FALSE);
        JFrame f = new JFrame("Print UI Example");
        f.addWindowListener(new WindowAdapter() {
           public void windowClosing(WindowEvent e) {System.exit(0);}
        JLabel label1=new JLabel("Selling Bill",JLabel.CENTER);
        JLabel label2=new JLabel("Customer Name :Mahmoud Saleh       ",JLabel.LEFT);
        JLabel label3=new JLabel("Buying Date :29/8/2008             ",JLabel.LEFT);
        JLabel label4=new JLabel("Book Buyed :Java Printing          ",JLabel.LEFT);
        JLabel label5=new JLabel("Number : 6 Copies                  ",JLabel.LEFT);
        JLabel label6=new JLabel("Total Price :600 $                 ",JLabel.LEFT);
        label1.setFont(new Font("Courier New", Font.BOLD, 13));
        label2.setFont(new Font("Courier New", Font.BOLD, 13));
        label3.setFont(new Font("Courier New", Font.BOLD, 13));
        label4.setFont(new Font("Courier New", Font.BOLD, 13));
        label5.setFont(new Font("Courier New", Font.BOLD, 13));
        label6.setFont(new Font("Courier New", Font.BOLD, 13));
        JButton printButton = new JButton("Print This Window");
        printButton.addActionListener(new PrintUIWindow(f));
        JPanel panel=new JPanel();
        panel.setLayout(new GridLayout(6,1));
        panel.add(label1);
        panel.add(label2);
        panel.add(label3);
        panel.add(label4);
        panel.add(label5);
        panel.add(label6);
        f.setSize(300,300);
        f.setLocationRelativeTo(null);
        f.add(panel,BorderLayout.CENTER);
        f.add(printButton,BorderLayout.SOUTH);
        panel.setBackground(Color.WHITE);
        f.setResizable(false);
        f.setVisible(true);
}

First_knight wrote:
please tell me am i thinking right
about this method: setImageableArea(.....)
public void setImageableArea(double x, double y, double width, double height);
like I said, I've tried this method and it doesn't seem to do anything.
the width=the JFrame Width,the height=the JFrame Height right?actually, when printing, 72 points (printing version of pixels) = 1 inch, so to do WYSIWYG, you need width = JFrameWidth * 72.0 / Toolkit.getToolkit().getScreenResolution. Ditto with height
upper left beginningx(0)---------------------------200--------------------------------600-----------------------------------y(1000)upper right beginningyou need to do something like PageSetup.getImageableX and do Graphics.translate(x,y);
also, if your page width = 720, that = 10 inches - that's a wide page (unless its in landscape)
so if i want the JFrame To Be In The Center Of The Page I Would Choose From x=200 ,y=600 depending that frame width is 400Actually, it would be 300 - 700 in your example
Because when i tried to use:setImageableArea(200, 600, 400, 200);like the above code
no changes occurs in the printed paperYes. You need to offset the Graphics object

Calling a method on a jFrame from a jPanel that created by the jFrame

Hi all
I can not for the life of me work out how to do this.
Calling a method on a jFrame from a jPanel that created by the jFrame.
I have used this code to set a handle for one jPanel to another.
i.e I can create new jpanel and pass in handles from one to another but not back to the jFrame.
// this is sudo code
private Panel_Top topPanel;
private Menu_Panel menuPanel;
private DataPanel dataPanel;
//create new
    topPanel = new Panel_Top();
    menuPanel = new Menu_Panel();
    dataPanel = new DataPanel();
// add handles from one to another
    menuPanel.setDataPanel(dataPanel);
    topPanel.setDataPanel(dataPanel);
    topPanel.setMenu_Panel(menuPanel);
    dataPanel.setMenu_Panel(menuPanel);
// in each class I use this to set
public void setDataPanel(DataPanel dataPanel) {
    this.dataPanel = dataPanel;
}But I can not seam to get a handle back to the jFrame that created it.
Please help
as you can see I am trying but no luck so far
Thanks

class Life extends JPanel{
      pulic Life( JFrame owner )
            owner.doSomething(); // pass the JFrame to the constructor and feel free to use it
}[code[

Execute jar file: "could not find the main class" program will terminate

Hey,
I am new to Java. I have started to make a small java program which supposed to help me at my studies to lean the Dominic Memory System. I have used the latest version of Netbeans 5.5.1 to build my program in. I have two problems which I cannot figure out how to solve, please help me.
The first problem is that the java script I have made works when I compile it in Netbeans, but when I create a Jar file it does not work. I receive a pop up message in windows ?could not find the main class program will terminate? when I execute the jar file.
The second problem I have is that I need to compare the strings generated by the "numbers" and "TIP" and if the numbers is not identical the numbers in the ?Center? JPanel should be highlighted as red.
If anyone would like to clean up the code I would be pleased. I have copied quite a lot from anyone because of my one lack of knowledge.
* GoListener.java
* Created on 12. september 2007, 21:48
* To change this template, choose Tools | Template Manager
* and open the template in the editor.
package grandmaster;
import java.awt.event.*;
import javax.swing.*;
import java.util.Vector;
import java.util.StringTokenizer;
import java.awt.Color;
* @author Computer
public class GoListener implements ActionListener {
private JTextField viewer;
private JTextField TIP;
private JTextField freq;
private JTextField max_num;
private Vector numbers;
public GoListener(JTextField j,JTextField k, JTextField m, JTextField f, Vector n) {
freq = f;
max_num = m;
viewer = j;
numbers = n;
TIP = k;
public void actionPerformed(ActionEvent e){
int time = Integer.valueOf(max_num.getText());
int f = Integer.valueOf(freq.getText());
if (e.getActionCommand() == "GO") {
for (int i = 0; i< time;++i) {
int number=0;
number = (int)Math.floor(100*Math.random());
while(number>51){
number = (int)Math.floor(100*Math.random());
if(number<=9){
viewer.setText(" "+"0" + String.valueOf(number) + " ");
} else{
viewer.setText(" " + String.valueOf(number) + " ");
viewer.paintImmediately(viewer.getBounds());
numbers.add(number);
try {
Thread.sleep(f*1000);
} catch (Exception exp) {
viewer.setText(" XX ");
viewer.paintImmediately(viewer.getBounds());
if (e.getActionCommand() == "VIEW") {
try {
//int numb = Integer.valueOf( TIP.getText() ).intValue();
StringTokenizer tokenizer = new StringTokenizer(TIP.getText(), " ");
String[] split = null;
int tokenCount = tokenizer.countTokens();
if (tokenCount > 0) {
split = new String[tokenCount];
for (int current = 0; current < tokenCount; current++) {
split[current] = tokenizer.nextToken();
viewer.setText(" " + String.valueOf(numbers) + " ");
// k=numbers(1);
/*while(c<i){
String.valueOf(k).equals(split[1]);
c++;
TIP.setText(" " + split[2] + " ");
} catch (Exception exp) {
try {
//string testit = numb.toString();
//String str = "" + numb;
//viewer.setText(str);
//viewer.setText(numbers.toString());
numbers.clear();
} catch (Exception exp) {
* Main.java
* Created on 12. september 2007, 21:07
* To change this template, choose Tools | Template Manager
* and open the template in the editor.
package grandmaster;
import java.util.Vector;
import javax.swing.*;
import java.awt.event.*;
import javax.swing.JButton;
import java.awt.*;
import grandmaster.GoListener;
* @author Computer
public class Main extends JFrame {
private JTextField viewer;
public JTextField TIP;
// private TextInputPanel TIP;
private Vector numbers;
/** Creates a new instance of Main */
public Main() {
numbers = new Vector();
JPanel p = new JPanel(new GridLayout(0,4));
JButton go = new JButton();
JButton view_num = new JButton();
go.setText("Go!");
go.setVisible(true);
go.setActionCommand("GO");
view_num.setText("VIEW");
view_num.setVisible(true);
view_num.setActionCommand("VIEW");
JTextField max_num = new JTextField();
max_num.setText("5");
JTextField freq = new JTextField();
freq.setText("1");
viewer = new JTextField();
viewer.setText("XX");
TIP = new JTextField("");
p.add(go);
p.add(max_num);
p.add(freq);
p.add(view_num);
getContentPane().add(p,BorderLayout.NORTH);
getContentPane().add(viewer,BorderLayout.CENTER);
getContentPane().add(TIP,BorderLayout.SOUTH);
setSize(200,200);
GoListener g = new GoListener(viewer,TIP,max_num, freq, numbers);
go.addActionListener(g);
view_num.addActionListener(g);
* @param args the command line arguments
public static void main(String[] args) {
// TODO code application logic here
Main window = new Main();
window.setVisible(true);
}

NetBeans questions should be posted to the NB site. It has mailing lists and associated forums.
This tutorial from the NB site addresses running programs outside of NB
http://www.netbeans.org/kb/articles/javase-deploy.html
When you compare objects, use ".equals()" and reserve == for comparing values.

Resizing JFrame on button click to show an image on the JFrame

Dear All,
I have a JFrame which has an empty label. On button click I want to set an icon for the label and want the JFrame to be resized to show that icon. I am using frame.pack() and I am not using any other sizing function. The code that I have right now, prints the image on the panel, but does not resize the frame to show the image. Pleae could someone help.package gui;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
public class ComponentDemo extends JPanel implements ActionListener,
ItemListener, MouseListener, KeyListener {
     private JTextArea textarea;
     private JButton button;
     private final static String newline = "\n";
     private JLabel imageIcon;
     public ComponentDemo() {
          button = new JButton("JButton welcomes you to CO2001");
          button.addActionListener(this);
          add(button);
          textarea = new JTextArea(10, 50);
          textarea.setEditable(false);
          addMouseListener(this);
          textarea.addKeyListener(this);
          JScrollPane scrollPane = new JScrollPane(textarea);
          add(scrollPane);
          imageIcon = new JLabel();
          add(imageIcon);
          setBackground(Color.pink);
          new JScrollPane(this);
      * Create the GUI and show it. For thread safety, this method should be
      * invoked from the event-dispatching thread.
     private static void createAndShowGUI() {
          // Create and set up the window.
          JFrame frame = new JFrame("Simple FrameDemo");
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
          frame.setLocation(700, 200);
          // get the content pane and set the background colour;
          frame.add(new ComponentDemo());
     //     frame.setSize(screenSize);
          // frame.getContentPane().setBackground(Color.cyan);
          // Display the window.
          frame.pack();
          frame.setVisible(true);
          frame.setResizable(true);
     public static void main(String[] args) {
          // Schedule a job for the event-dispatching thread:
          // creating and showing this application's GUI.
          javax.swing.SwingUtilities.invokeLater(new Runnable() {
               public void run() {
                    createAndShowGUI();
     @Override
     public void actionPerformed(ActionEvent e) {
          // TODO Auto-generated method stub
          if (e.getSource() instanceof JButton) {
               // System.out.println(e.getSource());
               String text = ((JButton) e.getSource()).getText();
               textarea.append(text + newline);
               textarea.setBackground(Color.cyan);
               textarea.setForeground(Color.BLUE);
               textarea.setCaretPosition(textarea.getDocument().getLength());
               imageIcon.setIcon(createImageIcon("SwingingDuke.png",
               "Image to be displayed"));
     @Override
     public void itemStateChanged(ItemEvent arg0) {
          // TODO Auto-generated method stub
     @Override
     public void mouseClicked(MouseEvent arg0) {
          textarea.append("A Mouse click welcomes you to CO2001" + newline);
          textarea.setBackground(Color.green);
          textarea.setCaretPosition(textarea.getDocument().getLength());
     @Override
     public void mouseEntered(MouseEvent arg0) {
          // TODO Auto-generated method stub
     @Override
     public void mouseExited(MouseEvent arg0) {
          // TODO Auto-generated method stub
     @Override
     public void mousePressed(MouseEvent arg0) {
          // TODO Auto-generated method stub
     @Override
     public void mouseReleased(MouseEvent arg0) {
          // TODO Auto-generated method stub
     @Override
     public void keyPressed(KeyEvent e) {
          System.out.println(e.getKeyChar());
          textarea.append("The key " + e.getKeyChar()
                    + " click welcomes you to CO2001" + newline);
          textarea.setBackground(Color.YELLOW);
          textarea.setFont(new Font("Arial", Font.ITALIC, 16));
          textarea.setCaretPosition(textarea.getDocument().getLength());
     @Override
     public void keyReleased(KeyEvent e) {
          System.out.println(e.getKeyChar());
          // textarea.append("The key "+
          // e.getKeyChar()+" click welcomes you to CO2001" + newline);
          // textarea.setBackground(Color.green);
          // textarea.setCaretPosition(textarea.getDocument().getLength());
     @Override
     public void keyTyped(KeyEvent e) {
          // TODO Auto-generated method stub
          System.out.println(e.getKeyChar());
          // textarea.append("The key "+
          // e.getKeyChar()+" click welcomes you to CO2001" + newline);
          // textarea.setBackground(Color.blue);
          // textarea.setCaretPosition(textarea.getDocument().getLength());
     /** Returns an ImageIcon, or null if the path was invalid. */
     protected ImageIcon createImageIcon(String path, String description) {
          java.net.URL imgURL = getClass().getResource(path);
          if (imgURL != null) {
               System.out.println("found");
               return new ImageIcon(imgURL, description);
          } else {
               System.err.println("Couldn't find file: " + path);
               return null;
}

myJPanel.setPerferredSize(new Dimension(new_width, new_hight));
myJFrame.pack();

What is the Popup class used for

I always thought that a Popup should have some basic functionality, such as the pupup should close when:
a) the escape key is pressed
b) the popup loses focus
The popup class provides none of the above functionality and in     fact seems to require some obscure code to
even get the keyboard focus to work properly.
Using a JWindow seems to provide the same functionality as a Popup.
JPopupMenu seems to support both of the above requirements.
Run the following program:
a) click on each of the buttons
b) click on an empty part of the frame
It appears to me that whenever you need a "popup" you should use a JPopupMenu.
Is the Popup class good for anything? Does it provide any functionality that I am not aware of?
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;
public class PopupTest extends JFrame
     String[] numbers = { "one", "two", "three", "four", "five" };
     public PopupTest()
          getContentPane().setLayout( new FlowLayout() );
          JButton popup = new JButton("Popup as Popup");
          popup.addActionListener(new ActionListener()
               public void actionPerformed(ActionEvent e)
                    popupPopup(e);
          getContentPane().add(popup);
          JButton window = new JButton("Window as Popup");
          window.addActionListener(new ActionListener()
               public void actionPerformed(ActionEvent e)
                    windowPopup(e);
          getContentPane().add(window);
          JButton menu = new JButton("PopupMenu as Popup");
          menu.addActionListener(new ActionListener()
               public void actionPerformed(ActionEvent e)
                    menuPopup(e);
          getContentPane().add(menu);
     private void popupPopup(ActionEvent e)
          JList list = new JList(numbers);
          list.setSelectedIndex(0);
          PopupFactory factory = PopupFactory.getSharedInstance();
          Popup popup = factory.getPopup(this, list, getLocation().x, getLocation().y);
          popup.show();
          Window window = SwingUtilities.windowForComponent(list);
          if (window != null)
               window.setFocusableWindowState(true);
          KeyboardFocusManager.getCurrentKeyboardFocusManager().focusNextComponent(list);
     private void windowPopup(ActionEvent e)
          JList list = new JList(numbers);
          list.setSelectedIndex(0);
          JWindow window = new JWindow(this);
          window.getContentPane().add(list);
          window.pack();
          window.setVisible(true);
          window.setLocation(getLocation().x + 200, getLocation().y);
     private void menuPopup(ActionEvent e)
          JList list = new JList(numbers);
          list.setSelectedIndex(0);
          Component c = (Component)e.getSource();
          JPopupMenu menu = new JPopupMenu();
          menu.add(list);
          menu.show(c, 0, 0);
          list.requestFocusInWindow();
     public static void main(String[] args)
          PopupTest frame = new PopupTest();
          frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
          frame.setSize(500, 200);
          frame.setLocationRelativeTo( null );
          frame.show();
}

you'd use Popup like JPopupMenu does, via a PopupFactoryYes you can get the Popu from the PopupFactory, but I think you are missing the point of my question. Popup has two methods, hide/show. It provides no other funtionality. I must write code to handle the escapce key and close the popup when it loses focus.
When I use a JPopupMenu and add a component to the menu, it appears to add some listeners to the component to handle the escape key and loss of focus.
I think it's safe to say that you're right when you say that it's preferable to use
JPopupMenu (my experience as well).That was my conclusion, but I was just wondering it I was missing anything.
It turns out that there are used in tooltips which, by essence, don't need any
input from the user (whether keyboard or mouse) I guess thats what I was missing, only use a Popup in tooltip type situations.

How to resize the components in a JFrame when the JFrame Resizes?

Hi all,
i have some problems with my app. I have set the JFrame resizable and that works fine for the JFrame but not for the components in the JFrame.
So my question is how can i set the components in a JFrame to resize automatically when the JFrame resizes?
Here are the important things from my code,...if you need more, just let me know, its my first post in a forum .
Its a JFrame with a JTabbedPane and on the Tabs are Panels with buttons and Tables.
Thank you in advance!
public class MainMonitor extends JFrame {
public MainMonitor() {
          super();
          initialize();
          setVisible(true);
     private void initialize() {
          this.setSize(1145, 785);
          this.setIconImage(Toolkit.getDefaultToolkit().getImage("Images/c.gif"));
          this.setContentPane(getJContentPane());
          this.setTitle("Company Manager");
          this.setResizable(true);
          this.setLocationRelativeTo(null);
     private JPanel getJContentPane() {
          if (jContentPane == null) {
               jContentPane = new JPanel();
               jContentPane.setLayout(null);
               jContentPane.setOpaque(true);
               jContentPane.add(getJTabbedPane(), null);
               jContentPane.add(getJPanel11(), null);
          return jContentPane;
     private JTabbedPane getJTabbedPane() {
          if (jTabbedPane == null) {
               jTabbedPane = new JTabbedPane();
               jTabbedPane.setLocation(new Point(6, 69));
               jTabbedPane.setSize(new Dimension(1120, 684));
               jTabbedPane.addTab("P", null, getJPanel(), null);
               jTabbedPane.addTab("K", null, getJPanel1(), null);
               jTabbedPane.addTab("B", null, getJPanel2(), null);
          return jTabbedPane;


Giasaste wrote:
Thanks a lot, i didnt knew that the Layout Manager is a must.It's not a must, but it is the way to allow your app to be resized nicely and makes it much easier to maintain and enhance your program. Imagine creating a complex gui then later decide that you want another radiobutton and to remove a jlabel / jtextfield pair. with layout managers a chore becomes easy.

Could not find the main class (with every jar)

This isn't a developer question. I get the error Could not find the main class with every jar I try to open (for example the jar downloaded from https://gjar.dev.java.net/ gives the same problems - and I don't think there is something wrong with that JAR). It isn't a problem with the jar or MANIFEST because the same jar works fine on my laptop. So there is something wrong with my JRE installation, but what?
I tried to remove and reinstall the JRE 6 Update 18 but that didn't work. When I run the JAR with command line java -jar "file.jar" it works fine, but if I dubbelclick on it I get the error message (and it's irritating me).
I'm a bit desperate so I hope that someone here can help me ;)
Thanks in advanced

hai T.B.M ... Sorry to post here... I know that i posted my question in wrong thread..but i dont have another solution to contact with you.. I had seen your answers which are really excellent and helped to do my project..
Now i am having very less time to complete my project and i am very new to JMF.. I am not getting output in JMF video capture ..please check the code and guide me where i gone wrong.......please pardon me once again to post here.. Heres my code
import javax.media.*;
import java.awt.*;
import javax.swing.*;
import java.util.*;
import java.awt.event.*;
import javax.media.protocol.*;
import java.io.*;
import javax.media.control.StreamWriterControl;
public class webcam implements ActionListener,ControllerListener
boolean eomReached = false;
boolean realized = false;
JFrame f;
BorderLayout bd1;
CaptureDeviceInfo device;
MediaLocator m1;
Player player;
Component videoScreen;
JButton b1,b2;
Processor processor;
DataSource ds=null;
DataSink fileWriter=null;
JLabel status=new JLabel("");
public webcam()
try
JFrame f=new JFrame();
JPanel p =new JPanel();
JPanel p1=new JPanel();
device=CaptureDeviceManager.getDevice("vfw:Microsoft WDM Image Capture (Win32):0");
m1=device.getLocator();
System.out.println("1");
processor.configure();
processor = Manager.createProcessor(m1);
processor.setContentDescriptor(new
FileTypeDescriptor(FileTypeDescriptor.MSVIDEO));
ds=processor.getDataOutput();
player.addControllerListener(this);
MediaLocator dest = new MediaLocator("file://foo.avi");
fileWriter = Manager.createDataSink(ds, dest);
fileWriter.open();
ds.connect();
ds.start();
player=Manager.createPlayer(m1);
player.addControllerListener(this);
blockingRealize();
videoScreen=player.getVisualComponent();
b1=new JButton("START");
b2=new JButton("STOP");
bd1=new BorderLayout();
p.setLayout(bd1);
p1.add(b1);
p1.add(b2);
p.add("South",p1);
p.add("East",videoScreen);
f.getContentPane().add(p);
f.setVisible(true);
f.setSize(500,500);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
b1.addActionListener(this);
b2.addActionListener(this);
catch(Exception e){}
public void actionPerformed(ActionEvent e)
if(e.getSource()==b1)
try{
processor.start();
player.start();
fileWriter.start();
catch(Exception e1){}
if(e.getSource()==b2)
try{
player.stop();
processor.stop();
processor.close();
fileWriter.close();
catch(Exception e2){}
public static void main(String args[])
webcam obj=new webcam();
public synchronized void blockingRealize() {
player.realize();
while (!realized) {
try {
wait();
} catch (java.lang.InterruptedException e) {
status.setText("Interrupted while waiting on realize...exiting.");
System.exit(1);
public synchronized void controllerUpdate (ControllerEvent event) {
System.out.println("myPlayer generated "+event.toString());
if (event instanceof RealizeCompleteEvent) {
realized = true;
notify();
} else if (event instanceof EndOfMediaEvent) {
eomReached = true;
}

Could not find the main class in Eclipse

Hey,
I've been working with Java for a few years now, but I recently set-up a new Eclipse-environment and now my Application won't run...
"Could not find the main class. Program will exit."
If I compile and run the source myself it works fine, so it must be a setting in Eclipse somewhere...
It doesn't work, even when I put the class in the default package...
It must be something very stupid, but I can't seem to find out what the problem is :(

It was only the basic Hello-World-concept;
public class Game extends JFrame {
     /** A default SerialVersionUID */
     private static final long serialVersionUID = 1L;
     public Game() {
          addKeyListener(new GameController());
          MainView view = new MainView(...);
          add(view);
      * @param args The game-options
     public static void main(String[] args) {
          Game spel = new Game();
          spel.setSize(1024, 768);
          spel.setTitle("Java Rally");
          spel.setResizable(false);
          spel.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          spel.setVisible(true);
}

Executable JAR sometimes could not find the main class.

I have a little task, that seems to be trivial- but I have no idea how to solve the current problem.
With a double click on my jar, a message comes up: JVM could not find the main class. Program will exit.
The executable JAR is an export result from eclipse, with a manifest file that contains the right entry to the main class.
But the curious thing is, that I have tested the little Swing-Application with 3 JRE versions: 1.4.2._06, 1.4.2_09 and 1.5 on Win2K and XP. Every time it works fine, but on one system it fails. (Normally it requires no external classpath settings, no path-entries to work.)
The ugly system is Win XP with JRE 1.4.2_06 installed.
Is there anybody with a good hint?
Please let me know.
Christiane

OK, I ll try to explain it in other words:
It is an executable jar file, with a manifest file that specifies the Main-Class. No other external files or jars or settings needed. Only a simple JDialog initialized from a parent JFrame.
I d like to start it with a double click from the Win-Explorer, not from command line!
As a result a dialog from "Java Virtual machine Launcher" displays
"Could not find the main class. Programm will exit."
My Problem is, I don t understand the launching process in depth. But I can reproduce the message with the following command:
wrong:
javaw -cp OrderAlertTest.jar OrderAlertParentDialog
-> Error dialog appears
correct:
javaw -cp OrderAlertTest.jar apo.order.OrderAlertParentDialog
-> OK
Any idea?
Christiane

The JFrame class

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