We Keep Coding

Intellij, "contentPane cannot be set to null" using swing designer

I'm trying out intellij, and am trying to do some swing development. I am running into an issue I have never experienced on eclipse, and I am wondering if I have something set up wrong.
Here is my GUI class that is run by my driver:
package view;
import javax.swing.*;
import java.awt.*;
public class View {
private JPanel panel;
public void run() {
JFrame frame = new JFrame("Vending Machine");
frame.setContentPane(new View().panel);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
}
{
// GUI initializer generated by IntelliJ IDEA GUI Designer
// >>> IMPORTANT!! <<<
// DO NOT EDIT OR ADD ANY CODE HERE!
$$$setupUI$$$();
}
/**
* Method generated by IntelliJ IDEA GUI Designer
* >>> IMPORTANT!! <<<
* DO NOT edit this method OR call it in your code!
*
* #noinspection ALL
*/
private void $$$setupUI$$$() {
final JPanel panel1 = new JPanel();
panel1.setLayout(new GridBagLayout());
}
}
as far as I can tell, my run() method is as straightforward as it gets. However, upon compiling, this is the error I receive:
Exception in thread "main" java.awt.IllegalComponentStateException: contentPane cannot be set to null.
at javax.swing.JRootPane.setContentPane(JRootPane.java:621)
at javax.swing.JFrame.setContentPane(JFrame.java:698)
at view.View.run(View.java:13)
at model.VendingMachine.<init>(VendingMachine.java:14)
at controller.Driver.main(Driver.java:14)
For whatever reason, the intellij autocreated code that does not properly initialize the JPanel, which is why it's null.
I've tried instantiating it myself inside run (panel = new JPanel();) but that has not helped.
Is this something obvious? I've never run into this issue when getting started with swing in eclipse.

You are setting as JFrame' s content pane the panel 'panel' but the JPanel you are creating is called 'panel1'. To fix this problem change JPanel' s name to 'panel' instead of 'panel1'.

Try enabling "UI Designer" plugin in Intellij IDEA, it helped in my case.
File -> Settings -> Plugins -> UI Designer -> Restart IDE

You need to make sure to to set the field name of the panel. You are possibly misunderstanding the following line:
frame.setContentPane(new View().panel);
In this code, new View().panel is really trying to initialize the object with the field name. So if the panel doesn't have that name...obviously you are trying to instantiate something that doesn't exist.
I named my JPanel MainPanel under the field name property in the jform editor and wrote:
frame.setContentPane(new View().MainPanel);

JavaFX Application with SwingNode doesn't maximise properly on some machines

I have a slightly complicated JavaFX GUI with the following component structure (simplified) as shown below. You will see that a SwingNode is used to contain the main bulk of the application, but I cannot tell you the design principle behind this since I didn't write the original code.
I am aware of various cautions about occasional odd behaviour when Swing & JavaFX are mixed, but there isn't the time at present to re-write the UI. The application is built to run on a Windows 7/8/10 platform, and what I'm seeing is as follows:
(a) On three different platforms I've tested (Windows XP native, Windows 7 VM, Windows 8 VM, different size monitors), when the application's Windows "maximize" decoration is clicked, the application resizes OK (by which I mean it is slightly jumpy and delayed, but the actual repainting to fill the screen is done correctly).
(b) However, on one further platform, the 'maximize' causes the entire content of the Stage to go white, and doesn't repaint properly until, say, a menu or one of its items is clicked. The machine in question is a Dell Optiplex 64-bit Windows 7 Pro SP1 with a DVI monitor of 1920 x 1080 sourced from an Intel HD Graphics 4600. ClearType is set to ON, and the version of Java is 1.8.0_73_b02.
There is one further question on SO regarding this issue, but it was created in June 2015 and never answered, so I'm not sure what to think.
Has anyone else come across this issue and/or feels able to comment on what might be causing it ? Is there some sort of 'revalidate/repaint' code, or JavaFX equivalent, which might be worth me trying as a workaround ?
public class Main extends Application
{
private SwingNode mainSwingNode = new SwingNode();
private JPanel mainPanel = new JPanel();
public void start(Stage primaryStage) throws Exception
{
BorderPane parent = new BorderPane(mainSwingNode);
Scene scene = new Scene(parent, 1024, 768);
// Build Swing components
SwingUtilities.invokeLater(() ->
{
createAndShowGUI();
mainSwingNode.setContent(mainPanel);
});
primaryStage.setScene(scene);
primaryStage.show();
}
public void createAndShowGUI()
{
mainPanel.setLayout(new BorderLayout());
// Setup canvas area & canvas rulers
mCanvasTabbedPane.setPreferredSize(new Dimension(800,600));
mainPanel.add(mCanvasTabbedPane, BorderLayout.CENTER);
menubar.initForActionsMap(menuActionsMap);
// Listen for property changes for site to enable/disable menus
ProjSingleton.getInstance().addPropertyChangeListener(menubar);
mainPanel.add(menubar, BorderLayout.NORTH);
// Setup show/hide sidebar button
btnShowSidebar = new JButton(menuActionsMap.get(ShowSidebarAction.class));
menubar.add(Box.createHorizontalGlue());
menubar.add(btnShowSidebar);
btnShowSidebar.setOpaque(false);
btnShowSidebar.setAlignmentX(JComponent.RIGHT_ALIGNMENT);
btnShowSidebar.setBorder(new EmptyBorder(new Insets(2,2,2,2)));
// Add site manager toolbar
sidebar.setLayout(new GridLayout(2, 0));
sidebar.setAlignmentX(JComponent.RIGHT_ALIGNMENT);
sidebar.add(siteManagementPanel);
sidebar.add(new JScrollPane(layerManagerView));
mainPanel.add(sidebar, BorderLayout.EAST);
Main.statusBar = new StatusBar();
Main.statusBar.setCanvasTabbedPane(mCanvasTabbedPane);
mainPanel.add(Main.statusBar, BorderLayout.SOUTH);
mainPanel.setVisible(true);
}
....
....
}

Swing Application Window not responding on Mac

I'm trying to get a basic Swing Application to run on my Mac OS X 10.8.2 (Java version 1.6.0_37) machine, and every time I try to run it from Eclipse, the frame appears, but I can't interact with it.
I've tried to start from a basic, clean slate where I create a new Swing Application Window project in Eclipse (WindowBuilder->Swing Designer->Application Window). This generates the following skeleton code:
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JButton;
import java.awt.BorderLayout;
public class Test {
private JFrame frame;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
Test window = new Test();
window.frame.setVisible(true);
window.frame.pack();
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public Test() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frame = new JFrame();
frame.setBounds(100, 100, 450, 300);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JButton btnPress = new JButton("Press");
frame.getContentPane().add(btnPress, BorderLayout.CENTER);
}
}
Everything seems to be fine, but when I run this from Eclipse, the frame doesn't let me interact with any components (in my non-example code, there are buttons and tabs).
Also, in the console, I see things like:
2012-11-09 14:30:27.624 java[8107:707] [Java CocoaComponent compatibility mode]: Enabled
2012-11-09 14:30:27.626 java[8107:707] [Java CocoaComponent compatibility mode]: Setting timeout for SWT to 0.100000
Is there some Mac-specific setting that I have to change? (I'm using the latest default Mac JRE)

The program runs fine on my machine under OSX, but it could be the missing
window.frame.pack();
Have you tried this?
Test window = new Test();
window.frame.pack();
window.frame.setVisible(true);

I had the same problem when using the DJ Swing library in my application (it uses SWT). Interestingly, the problem occurred even though I didn't initialise DJ Swing explicitly. It now works because I have added DJ Swing initialisation:
public class SwingAppTest {
public static void main(String[] args) {
NativeInterface.open();
UIUtils.setPreferredLookAndFeel();
SwingUtilities.invokeLater(new Runnable() {
public void run() {
JFrame frame = new JFrame("Example");
frame.getContentPane().setLayout(new BorderLayout());
frame.setPreferredSize(new Dimension(400, 200));
frame.setBounds(0,0,200,200);
frame.setTitle("blah");
JButton blah = new JButton("blah");
blah.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.out.println("button clicked");
}
});
frame.getContentPane().add(blah, BorderLayout.CENTER);
frame.setVisible(true);
}
});
NativeInterface.runEventPump();
}
}

Apple is no longer supporting Java in is operating systems after 10.6:
Apple not committing to Java support in Mac OS X 10.7
seems like missing or incompatible library files in the JRE.

that is weird. I tried your sample (no linux) and don't see any problem there.
So as Wayne mentioned, might be macos issue.
Btw, what is your java version you're using?
On the other hand problem might be in the code you didn't share with us => hard to guess :)
EDIT: OK, so it seems you're playing "guess what I have in my code" game with us :) As my assumption is that code not shown causes problem.
It reminds me of some of these Poiroit/Agatha Christie detective stories, where just a little detail might have significant impact on the reality.
This is the reason for my theory:
code shown uses Java swing library (import javax.swing. ...) + Awt (import java.awt. ...) - this combonation is a common use case, however
the error message you shared shows SWT library error (Setting timeout for SWT to 0.100000)
So to me it seems like you're mixing things that should never be mixed.
As Swing is java UI library that is completely OS independent (originally Sun made) that is built on top of Awt. However SWT is completely different java UI library which is kind of mix of native calls with java on it (originally IBM made).
Therefor I'd suggest to double check your code and make sure that if you use JFrame, the only library components you have there are from Swing (javax.swing....) / Awt (java.awt. ...).

I've been knocking my head against a wall for days trying to get this working and finally found the answer:
'It's solved now - it was just a case of removing swt.jar from the project dependencies.'
Hey presto!!!!

In my case, I was trying to code a game where I used jPanel. I needed to override the paint method and added pack(); to the main and it finally showed me what I was trying to draw.

export a JOGL applet and embedd into a html page

It is some time that I'm testing opengl with java and JOGL. I have a good result and I wan to publish it on the web, but I have a problem. I'm in eclipse, and I'm testing an Applet with JOGL.
EDIT: Thanks to Ricket answer it fixed this problem
first of all i have this run time error (but the program works correctly):
java.lang.IllegalArgumentException:
adding a window to a container at
EDIT: but it still doesn't work:
then I found this incredibly clear page
and I did what is said. I open html with the browser, the libs are downloaded, but it stops at Starting applet AppletHelloWorld, as that is the name I gave to my applet.
Maybe I am missing something like a main function or exporting the jar properly?
This is my main code:
public class AppletHelloWorld extends Applet
{
public static void main(String[] args)
{
JFrame fr=new JFrame();
fr.setBounds(0,0,1015,600);
fr.add(new AppletHelloWorld());
fr.setVisible(true);
}
public void init()
{
setLayout(null);
MyJOGLProject canvas = new MyJOGLProject(); //MyJOGLProject extends JFrame
canvas.run(); // this do setVisible(true)
} //....

Just as the error says, you're trying to add a window to a container. A JFrame is a window. You can't add a JFrame to anything, including a Container. I think perhaps you either don't know what a JFrame is, or don't know what a Container is.
Ideally you would have MyJOGLProject extend GLEventListener instead. Then your init function would make a new GLCanvas, add an instance of MyJOGLProject to it (via addGLEventListener), and then add the GLCanvas to your applet.
Alternatively, if you're okay with the applet popping up a JFrame, then simplify your init method:
public void init() {
setLayout(null);
MyJOGLProject canvas = new MyJOGLProject();
canvas.setVisible(true);
}
That should do it.

Use JApplet. I think that's the reason why it fails.
(Use Webstart with JNLP in NetBeans)

Why my Swing based GUI application is not responding?

I am trying to create my first GUI application using (Java + Eclipse + Swing). This is my code:
import java.awt.*;
import javax.swing.*;
public class HelloWorldSwing extends JFrame {
JTextArea m_resultArea = new JTextArea(6, 30);
//====================================================== constructor
public HelloWorldSwing() {
//... Set initial text, scrolling, and border.
m_resultArea.setText("Enter more text to see scrollbars");
JScrollPane scrollingArea = new JScrollPane(m_resultArea);
scrollingArea.setBorder(BorderFactory.createEmptyBorder(10,5,10,5));
// Get the content pane, set layout, add to center
Container content = this.getContentPane();
content.setLayout(new BorderLayout());
content.add(scrollingArea, BorderLayout.CENTER);
this.pack();
}
//============================================================= main
public static void main(String[] args) {
JFrame win = new HelloWorldSwing();
win.setTitle("TextAreaDemo");
win.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
win.setVisible(true);
}
}
The code was taken from here.
When I run the application from Eclipse the expected window appears (So, it's good. I see what I want to see). However, when I try to close the window or try to write something in the text area the program freezes. The OS writes me that program is not responding (I try it on Ubuntu).
Can anybody help me to find the reason of the problem?
Thank you in advance for any help.

I'm sure this doesn't have to do with the code, as others have found the code runs just fine on their machines - which points to a machine specific issue. From within Eclipse, make sure it is setup to use the expected JDK/JRE. However, before worrying about how Eclipse is handling your situation, I'd run things by hand first - especially since you've got a very simple class.
I would check to ensure that you're using the expected compiler and runtime. On Linux:
which javac
which java
If they're both what you expect, do the following:
javac HelloWorldSwing.java
java HelloWorldSwing
If you get a similar problem, then you know it's not the Eclipse configuration and it's something else. If you're not using the latest JDK, upgrade to the latest. If you're already at the latest, it could be a display driver. Do other JAVA swing programs work on this computer? I'm sure you could find some on the net, download an app already packaged as a jar and try running it.

did you try using the eventdispatcherthread to view the JFrame?
something like:
public static void main(String[] args){
SwingUtilities.invokeLater(new Runnable(){
public void run(){
createAndViewJFrame();
}
});
}
public void createAndViewJFrame(){
JFrame win = new HelloWorldSwing();
win.setTitle("TextAreaDemo");
win.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
win.setVisible(true);
}
then your frame would be shown by the swing dispatcher thread.
hope it helped, although im just guessing...
Update: as commenters pointed you i f**ed up the invokeLater() call. I just edited this post to correct that. Thanx go to yishai & willcodejavaforfood for pointing it out!
frank

You need to catch the exit event and
respond with a System.exit( 0 );
You should be able to find that in
most swing examples online.
wrong stuff... sorry... coffee... argh....