Problem with getLayout() on a JFrame

Hello,
Thank you for reading my post and trying to help me.
Something is a bit unclear to me. I create a JFrame object and give it a GridLayout as in the following:
JFrame frame = new JFrame();
frame.setLayout(new GridLayout(3, 2, 15, 15));I pass this JFrame object to another class constructor and save it as a private variable of type JFrame, and at some point I want to be able to return this GridLayout so I call getLayout() in a method of that class: GridLayout currentLayout = (GridLayout) frame.getLayout();.
I typecast the returned member because it is a LayoutManager, a class that GridLayout implements. When I run this code, I get a runtime error saying getLayout() returned a BorderLayout and I cannot typecast it to a GridLayout.
This is where I am confused. As I passted a GridLayout to setLayout() before, how come getLayout() gives me back a BorderLayout please? Is there anyway to get the GridLayout back rather than store it as a variable please (the use of this GridLayout is very rare, which is why I would like to avoid keeping a variable for it) ?
I really appreciate your help and thank you for helping me.

Jary316 wrote:
Thank you, it is a bit strange they chose it to work this way but it explains it.Not really when you read on why they do this: [http://java.sun.com/docs/books/tutorial/uiswing/components/toplevel.html]
It increases the flexibility and power of Swing.

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Edited by: akyra on Jan 14, 2008 4:36 AM
Edited by: akyra on Jan 14, 2008 4:37 AM
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If you need further help then you need to create a "Short, Self Contained, Compilable and Executable, Example Program (SSCCE)", that demonstrates the incorrect behaviour.
http://homepage1.nifty.com/algafield/sscce.html
Don't forget to use the "Code Formatting Tags", so the posted code retains its original formatting.
http://forum.java.sun.com/help.jspa?sec=formatting

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regards

you just need to change (at end of actionPerformed())
System.exit(0);
to
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Problem with setContentPane() in JFrame class

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Problem with JPanel in JFrame

hai ashrivastava..
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Hi
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Dear Experts,
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thanks a lot for your time , consideration and efforts.
jibby
Edited by: jibbylala on Sep 20, 2010 6:06 PM

jibbylala wrote:
thanks for mentioning as i wasn't able to write complete context here.Yep thanks camickr. I think that Darryl's succinct reply applies here as well.

Problem with JFrame class.

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

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getContentPane().add(jPanel1, new org.netbeans.lib.awtextra.AbsoluteConstraints(0, 0, x_co_or, y_co_or));
pack();
Can anybody suggest any idea/solution.
Any idea/solution are most welcome.
Regards,
Pradeep Dubey

How can i solve that I am using AbsoluteLayout(jre1.6)
and here i am going to provide you code snippet.no need for the snippet, you're using absolute positioning, which means you're responsible for location and size on every single change.
start coding now, take about a week, or you could use a layout manager, take maybe, 5 minutes

Problem with JFrame code

Can anyone say the problem with the attached code. When I run the program, only, maximize, minimize and close options are viewable and nothing else.
import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Image;
import java.awt.Insets;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.LineBorder;
* Created on Mar 24, 2008
* @author Anand
public class JBackGroundImageDemo extends JFrame
    Container con = null;
    JPanel panelBgImg;
    public JBackGroundImageDemo()
        setTitle("JBackGroundImageDemo");
        con = getContentPane();
        con.setLayout(null);
        ImageIcon imh = new ImageIcon("aditi.jpg");
        setSize(imh.getIconWidth(), imh.getIconHeight());
        panelBgImg = new JPanel()
            public void paintComponent(Graphics g)
                Image img = new ImageIcon("aditi.jpg").getImage();
                Dimension size = new Dimension(img.getWidth(null), img.getHeight(null));
                setPreferredSize(size);
                setMinimumSize(size);
                setMaximumSize(size);
                setSize(size);
                setLayout(null);
                g.drawImage(img, 0, 0, null);
        con.add(panelBgImg);
        panelBgImg.setBounds(0, 0, imh.getIconWidth(), imh.getIconHeight());
        GridBagLayout layout = new GridBagLayout();
        JPanel panelContent = new JPanel(layout);
        GridBagConstraints gc = new GridBagConstraints();
        gc.insets = new Insets(3, 3, 3, 3);
        gc.gridx = 1;
        gc.gridy = 1;
        JLabel label = new JLabel("UserName: ", JLabel.LEFT);
        panelContent.add(label, gc);
        gc.gridx = 2;
        gc.gridy = 1;
        JTextField txtName = new JTextField(10);
        panelContent.add(txtName, gc);
        gc.insets = new Insets(3, 3, 3, 3);
        gc.gridx = 1;
        gc.gridy = 2;
        gc.gridwidth = 2;
        JButton btn = new JButton("Login");
        panelContent.add(btn, gc);
        panelContent.setBackground(Color.GRAY);
        panelContent.setBorder(new LineBorder(Color.WHITE));
        panelBgImg.add(panelContent);
        panelBgImg.setLayout(new FlowLayout(FlowLayout.CENTER, 150, 200));
        setResizable(false);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    public static void main(String[] args)
        new JBackGroundImageDemo().setVisible(true);
     Please help.
Regards,
Anees

Here's you a little code example, it works, so take a look at it.
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.MediaTracker;
import java.awt.Toolkit;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Junk{
public Junk(){
public void makeFrame(){
    JFrame j = new JFrame("Junk");
    Toolkit t = Toolkit.getDefaultToolkit();
    MediaTracker mt = new MediaTracker(j);
    Image img = t.getImage("junk.jpg");
    mt.addImage(img, 0);
    try{
      mt.waitForID(0);
    }catch(InterruptedException e){
      System.out.println("Hey, we were too impatient!");
    myPanel p = new myPanel(img);
    p.setPreferredSize(new Dimension(img.getWidth(null), img.getHeight(null)));
    j.add(p);
    j.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    j.pack();
    j.setVisible(true);
public static void main(String[] args){
    new Junk().makeFrame();
class myPanel extends JPanel{
    Image img;
    myPanel(Image img){
      this.img = img;
    public void paintComponent(Graphics g){
      g.drawImage(img, 0, 0, this);
}BTW: your image should be in your project folder.

Problem with JFrame's dispose();

Hello everyone,
I'm having a problem with JFrame's dispose() method. In my program I have 2 classes which go into full screen. On each screen there is a button to switch to the other screen. The first time I push the button on both of them the other screen closes, which is what I want. However, if I push the same button more than twice - like by going from Screen1 to Screen2 and Screen2 to Screen1 and then Screen1 to Screen2 - I get 2 screens. If I keep doing that I eventually get 10+ screens up, which is bad. How do I prevent that?

There's a lot of code, so I'll just post up the part that does it.
backButton.addActionListener(new ActionListener()
              public void actionPerformed(ActionEvent e)
                  soundManagerM.close();
                    new MenuScreen().setVisible(true);
                    dispose();
         });I don't think it opens up 2 at once, because it would play multiple music right?

Problem with ScrollPane and JFrame Size

Hi,
The code is workin but after change the size of frame it works CORRECTLY.Please help me why this frame is small an scrollpane doesn't show at the beginning.
Here is the code:
import java.awt.*;
public class canvasExp extends Canvas
     private static final long serialVersionUID = 1L;
     ImageLoader map=new ImageLoader();
    Image img = map.GetImg();
    int h, w;               // the height and width of this canvas
     public void update(Graphics g)
        paint(g);
    public void paint(Graphics g)
            if(img != null)
                 h = getSize().height;
                 System.out.println("h:"+h);
                  w = getSize().width;
                  System.out.println("w:"+w);
                  g.drawRect(0,0, w-1, h-1);     // Draw border
              // System.out.println("Size= "+this.getSize());
                 g.drawImage(img, 0,0,this.getWidth(),this.getHeight(), this);
                int width = img.getWidth(this);
                //System.out.println("W: "+width);
                int height = img.getHeight(this);
                //System.out.println("H: "+height);
                if(width != -1 && width != getWidth())
                    setSize(width, getHeight());
                if(height != -1 && height != getHeight())
                    setSize(getWidth(), height);
}I create frame here...
import java.awt.*;
import java.awt.event.*;
import javax.swing.JFrame;
public class frame extends JFrame implements MouseMotionListener,MouseListener
     private static final long serialVersionUID = 1L;
    private ScrollPane scrollPane;
    private int dragStartX;
    private int dragStartY;
    private int lastX;
    private int lastY;
    int cordX;
    int cordY;
    canvasExp canvas;
    public frame()
        super("test");
        canvas = new canvasExp();
        canvas.addMouseListener(this);
        canvas.addMouseMotionListener(this);
        scrollPane = new ScrollPane();
        scrollPane.setEnabled(true);
        scrollPane.add(canvas);
        add(scrollPane);
        setSize(300,300);
        pack();
        setVisible(true);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    public void mousePressed(MouseEvent e)
        dragStartX = e.getX();
        dragStartY = e.getY();
        lastX = getX();
        lastY = getY();
    public void mouseReleased(MouseEvent mouseevent)
    public void mouseClicked(MouseEvent e)
        cordX = e.getX();
        cordY = e.getY();
        System.out.println((new StringBuilder()).append(cordX).append(",").append(cordY).toString());
    public void mouseEntered(MouseEvent mouseevent)
    public void mouseExited(MouseEvent mouseevent)
    public void mouseMoved(MouseEvent mouseevent)
    public void mouseDragged(MouseEvent e)
        if(e.getX() != lastX || e.getY() != lastY)
            Point p = scrollPane.getScrollPosition();
            p.translate(dragStartX - e.getX(), dragStartY - e.getY());
            scrollPane.setScrollPosition(p);
}...and call here
public class main {
     public main(){}
     public static void main (String args[])
         frame f = new frame();
}There is something I couldn't see here.By the way ImageLoader is workin I get the image.
Thank you for your help,please answer me....

I'm not going to even attempt to resolve the problem posted. There are other problems with your code that should take priority.
-- class names by convention start with a capital letter.
-- don't use the name of a common class from the standard API for your custom class, not even with a difference of case. It'll come back to bite you.
-- don't mix awt and Swing components in the same GUI. Change your class that extends Canvas to extend JPanel instead, and override paintComponent(...) instead of paint(...).
-- launch your GUI on the EDT by wrapping it in a SwingUtilities.invokeLater or EventQueue.invokeLater.
-- calling setSize(...) followed by pack() is meaningless. Use one or the other.
-- That's not the correct way to display a component in a scroll pane.
Ah, well, and the problem is that when you call pack(), it retrieves the preferredSize of the components in the JFrame, and you haven't set a preferredSize for the scroll pane.
Please, for your own good, take a break from whatever it is you're working on and go through The Java™ Tutorials: [Creating a GUI with JFC/Swing|http://java.sun.com/docs/books/tutorial/uiswing/TOC.html]
db

Is there a problem with JFrame and window listeners?

As the subject implies, i'm having a problem with my JFrame window and the window listeners. I believe i have implemented it properly (i copied it from another class that works). Anyway, none of the events are caught and i'm not sure why. Here's the code
package gcas.gui.plan;
import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Container;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
import java.util.Hashtable;
import javax.swing.JDialog;
import javax.swing.JFrame;
import gcas.plandata.TaskData;
import gcas.util.GCASProperties;
import gcas.gui.planlist.MainPanel;
* MainFrame extends JPanel and is the main class for the plan details window
public class MainFrame extends JFrame implements WindowListener
     * the container for this window
    private Container contentPane;
     * a string value containing the name of the plan being viewed
    private String labelText;
     * a string value containing the name of the window (GCAS - plan list)
    private static String title;
     * an instance of JDialog class
    private static MainFrame dialog;
     * hashTable that correlates the task name to its id as found in the
     * plan
    private Hashtable taskNameToId = new Hashtable();
     * an instance of taskSetPane. This is the current instance of taskSetPane
     * being viewed
    private PlanTaskSet currentPane;
     * instance of TaskData class. Each instance will hold information on
     * an individual task
    private TaskData taskData;
     * hashTable containing instances of the taskSetPane class
    private Hashtable taskSetPanes = new Hashtable();
     * an instance of the OuterPanel class
    OuterPanel mainPanel;
     * an instance of the ButtonPanel class
    ButtonPanel buttonsPanel;
     * an instance of the LeftPanel class
    LeftPanel leftPanel;
     * an instance of the the GCASProperties class
    GCASProperties gcasProps;
    private static MainFrame thisPlanMain = null;
    private MainPanel planListMain;
     * constructor for MainFrame
     * @param frame the parent frame calling this class
     * @param locationComp the location of the component that initiated the opening of the dialog
     * @param labelText the name of the plan that is being viewed
     * @param title title of window
    private MainFrame(JFrame frame, Component locationComp, String labelText,
            String title)
        super(title);
        gcasProps = GCASProperties.getInstance();
        mainPanel = new OuterPanel(labelText, currentPane,
                taskNameToId, taskSetPanes);
        leftPanel = mainPanel.getLeftPanel();
        System.out.println("LABLE: " + labelText);
        leftPanel.setMainPanelContents();
        buttonsPanel = new ButtonPanel(labelText, taskSetPanes,
                taskNameToId, leftPanel);
        contentPane = getContentPane();
        contentPane.add(mainPanel, BorderLayout.CENTER);
        contentPane.add(buttonsPanel, BorderLayout.PAGE_END);
        this.addWindowListener(this);
        this.labelText = labelText;
        pack();
        setLocationRelativeTo(locationComp);
        this.setVisible(true);
        planListMain = MainPanel.getInstance();
        planListMain.setVisible(false);
    public static MainFrame getInstance(JFrame frame, Component locationComp, String labelText,
            String title)
        if (thisPlanMain == null)
            thisPlanMain = new MainFrame(frame, locationComp, labelText,
                    title);
        return thisPlanMain;
    public static MainFrame getDialogObject()
    {   //from the location this is called (ButtonPanel), this will never
        //be null
        return thisPlanMain;
    public static void setABMDDialogNull()
        thisPlanMain = null;
     * returns an instance of MainFrame
     * @return MainFrame instance
    public static MainFrame getDialog()
        return dialog;
     * setter for MainFrame
     * @param aDialog a MainFrame instance
    public static void setDialog(MainFrame aDialog)
        dialog = aDialog;
     * window opened event
     * @param windowEvent the window event passed to this method
    public void windowOpened(WindowEvent windowEvent)
     * The window event when a window is closing
     * @param windowEvent the window event passed to this method
    public void windowClosing(WindowEvent windowEvent)
        gcasProps.storeProperties("PlanList");
        MainPanel abmd = MainPanel.getInstance();
//        planMain = this.getDialogObject();
//        if(planMain != null)
//            planMain.setVisible(false);
//            abmd.setVisible(true);
//            planMain.setABMDDialogNull();
        if(this.getDialogObject()!= null)
            abmd.setVisible(true);
            setVisible(false);
            setABMDDialogNull();
     * Invoked when the Window is set to be the active Window
     * @param windowEvent the window event passed to this method
    public void windowActivated(WindowEvent windowEvent)
     * Invoked when a window has been closed as the result of calling dispose on the window
     * @param windowEvent the window event passed to this method
    public void windowClosed(WindowEvent windowEvent)
     * Invoked when a Window is no longer the active Window
     * @param windowEvent the window event passed to this method
    public void windowDeactivated(WindowEvent windowEvent)
        System.out.println("HI");
     * Invoked when a window is changed from a minimized to a normal state
     * @param windowEvent the window event passed to this method
    public void windowDeiconified(WindowEvent windowEvent)
        //we could have code here that changed the way alerts are done
       System.out.println("Invoked when a window is changed from a minimized to a normal state.");
     * Invoked when a window is changed from a normal to a minimized state
     * @param windowEvent the window event passed to this method
    public void windowIconified(WindowEvent windowEvent)
        //we could have code here that changed the way alerts are done
//        System.out.println("Invoked when a window is changed from a normal to a minimized state.");
}anyone know whats wrong?

It turned out that my ide was running the old jar and not updating it, so no matter what code i added, it wasn't being seen. Everything should be fine now.

Weird problem with jpanel vs jframe

I'm using jmathplot.jar from JMathTools which lets me do 3d plotting. I used a JFrame to get some code to work and it worked fine. Here's the code that worked for a JFrame:
public class View extends JFrame
    private Model myModel;
    private Plot3DPanel myPanel;
    // ... Components
    public View(Model m)
        myModel = m;
        // ... Initialize components
        myPanel = new Plot3DPanel("SOUTH");
        myPanel.addGridPlot("Test",myModel.getXRange(),myModel.getYRange(),myModel.getZValues());
        setSize(600, 600);
        setContentPane(myPanel);
        setVisible(true);
}Here's the class that starts everything:
public class TestApplet extends JApplet
    public void init()
        //Execute a job on the event-dispatching thread; creating this applet's GUI.
        try
            SwingUtilities.invokeAndWait(new Runnable()
                public void run()
                    createGUI();
        catch (Exception e)
            e.printStackTrace();
    private void createGUI()
        System.out.println("Creating GUI");
        Model model = new Model();
        View view = new View(model);
}And here's the Model:
public class Model
    private double[] myXRange,myYRange;
    private double[][] myZValues;
    public Model()
        createDataSet();
    public double[] getXRange()
        return myXRange;
    public double[] getYRange()
        return myYRange;
    public double[][] getZValues()
        return myZValues;
    private void createDataSet()
        myXRange = new double[10];
        myYRange = new double[10];
        myZValues = new double[10][10];
        for(double i=0;i<10;i++)
            for(double j=0;j<10;j++)
                double x = i/10;
                double y = j/10;
                myXRange[(int) i] = x;
                myYRange[(int) j] = y;
                myZValues[(int) i][(int) j]= Math.cos(x*Math.PI)*Math.sin(y*Math.PI);
}However, as you can see, my main class is a JApplet because ideally I want View to be a JPanel that I add to the applet. All I did was change "extends JFrame" to "extends JApplet" and changed:
setSize(600, 600);
setContentPane(myPanel);
setVisible(true);to
this.add(myPanel);and added these two lines to createGUI():
        view.setOpaque(true);
        setContentPane(view);When I run it however, it appears really really small. It seems like its drawing the panel to the default size of the applet viewer and doesn't resize it when I resize the applet. I don't know if it's a problem with the library or if I'm doing something wrong in my applet.

However, as you can see, my main class is a JApplet because ideally I want View to be a JPanel that I add to the applet. All I did was change "extends JFrame" to "extends JApplet" and (...)What do you mean? View extends JApplet? I thought View was meant to extend JPanel in the end...
When I run it however, it appears really really small. It seems like its drawing the panel to the default size of the applet viewer and doesn't resize it when I resize the applet.Or, the panel has its preferred size, and this latter is too small. Actually the panel has the size its container's layout manager awards it (taking or not the panel's preferred, minimum, and maximum sizes into account). See the tutorial on [layout managers|http://java.sun.com/docs/books/tutorial/uiswing/layout/index.html] .
In particular, this line adds the myPanel to a parent panel (presumably, it is in class View which extends JPanel, whose default layout is FlowLayout):
this.add(myPanel);
I don't know if it's a problem with the library or if I'm doing something wrong in my applet.Likely not (presumably the library interfers only in how it computes the Plot3DPanel's preferred size). There's an easy way to tell: try to layout correctly a custom JPanel of yours, containing only e.g. a button with an icon. Once you understand the basics of layout management, revisit the example using ther 3rd-party library.
N.B.: there are a lot of "likely" and "presumably" in my reply: in order to avoid hardly-educated guesses especially on what is or isn't in your actual code, you'd better provide an SSCCE , which means reproducing the problem without the 3rd party library.

Problem with getLayout() on a JFrame

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