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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);

Access Panel from Main Form from a Panel Form

I am trying to access a panel from my Main JForm which I use as a dynamic panel that repaints different Panel Forms.
this is the hierarchy of the forms.
Package_Main-Main_Form(JForm)-Dynamic_Panel(Panel)-DashBoard(Panel_Form)
Package_Panels-Panel_A-Panel_B
What I did was Display JForm first and repaint its JPanel with DashBoard.
now heres the problem.
I have a button inside my dashboard and when I tried to import Package_Panels.PanelA, but it doesn't work properly.
heres the first code I tried:
This code was added inside DashBoard Button.
PanelA x = new PanelA ();
this.removeAll();
this.add(x);
this.revalidate();
this.repaint();
x.setVisible(true);
I had doubts about this one since I knew if i use this.function, it points out the DashBoard Panel.
anyone knows a way to access the JForm's panel?
UPDATE: I found a way around this by using this.getParent() but other ideas are welcome. I don't to be stuck doing this over and over again.
heres what I did:
Panel_A x = new Panel_A();
this.setVisible(false);
this.getParent().add(x);
this.getParent().revalidate();
this.getParent().repaint();
x.setVisible(true);
//this.getParent().remove(this); - Does this really work? I dont want to keep this instance open.

Simple Java GUI, cards not appearing

import javax.swing.*;
public class SlideShow {
JFrame slide = new JFrame("Slide Show");
public SlideShow(){
slide.setSize(300,400);
slide.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
slide.setVisible(true);
slide.setLocationRelativeTo(null);
JPanel panel = new JPanel();
JLabel label = new JLabel(new ImageIcon("Images/picture1"));
panel.add(label);
slide.add(panel);
}
public static void main(String[] args){
SlideShow slide = new SlideShow();
}
}
I have to create a simple Java GUI that displays some cards. First, I just wanted to test it by displaying one card. For some reason I can't seem to figure out why nothing is being displayed.

You haven't actually used a proper file name "Images/picture1". Should be something like "Images/picture1.png" with the file format
Also image files, generally should be read from the class path, if you plan on having them embedded to the program. To do so, you will first need to put the file in the class path. With most IDE build configurations it's as simple as placing the image in the src. So
ProjectRoot
src
images
picture1.png
Then you would read it like
new ImageIcon(getClass().getResource("/images/picture1.png"));
A better approach would be to use ImageIO.read(). If the file path is incorrect, it will throw an exception, so you know where you're going wrong
Image image = ImageIO.read(getClass().getResource("/images/picture1.png"));
ImageIcon icon = new ImageIcon(image);
You will need to put it in the try/catch block
Also do what codeNinja said about the setVisible() after adding component. Also preferably pack() the frame, instead of setSize()

You need to set the Frame visible after you add all necessary components to it. Move slide.setVisible(true); Down to the bottom of the constructor like this:
...
slide.add(panel);
slide.setVisible(true);
Alternatively you can add slide.revalidate(); at the bottom of your constructor.

How to change java icon in a JFrame

Ok so I've been researching this one quiet a bit. I am fairly new to java but thought that this one would be easy. Ive tried just about every way that has been answered on this site and still no luck, and usually when I look here I am able to find a answer that fits what I am looking for. Does anyone know how to change the Java icon in the top corner of the JFrame. I'm pretty positive that its not my file path either because all my images are in the same folder and they all work, this is the only one that I can't seem to get to work.
This is the first part my code for the main menu of my program, everything works except when i try to add the icon image. The code I've entered below does not have anything in it for the JFrame IconImage, I removed it since it didn't work. So if there is someone who knows how to get it working with this code that would be highly appreciated, thank you very much in advanced!
public class MainFrame
{
private MyPanel main;
private MyPanel2 create;
private MyPanel3 update;
private MyPanel4 find;
JFrame frame = new JFrame("Main Menu:");
public void displayGUI()
{
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel contentPane = new JPanel();
contentPane.setBorder(BorderFactory.createEmptyBorder(0, 0, 0, 0));
contentPane.setLayout(new CardLayout());
main = new MyPanel(contentPane, this);
create = new MyPanel2(contentPane);
update = new MyPanel3(contentPane);
find = new MyPanel4(contentPane);
contentPane.add(main, "Main Menu");
contentPane.add(create, "Create Part");
contentPane.add(update, "Update Part");
contentPane.add(find, "Find Part");
frame.setLocation(200, 200);
frame.setSize(700, 580);
frame.setContentPane(contentPane);
frame.setVisible(true);
}

I have an answer for you. First, make sure that the images are in a folder, not a package. Next, insert this line of code:
Image image = Toolkit.getDefaultToolkit().getImage(getClass().getResource("path/to/image.png"));
ImageIcon icon = new ImageIcon( );
setIconImage(icon.getImage());
This code gets the image from the class path, and returns it as a image icon, and then it sets it. This should add the image icon to the application. If it doesn't, then tell me.
EDIT: After you told me that that didn't work then I decided to take a second crack at it...
First, put your images into a completely separate folder. I usually call this /res. Next, put your image in there. Now, for loading I took a completely different route. I decided to use ImageIO instead of default loading. To load the image, you use this code:
try {
frame.setIconImage(ImageIO.read(new File("res/icon.png")));
}
catch (IOException exc) {
exc.printStackTrace();
}
ImageIO works a lot better for loading images. If this still doesn't work then please tell me.
If you want to export this as a JAR then put a folder the same name as you used in the program in the same directory as the JAR.

For example in a NetBeans project, create a resources folder in the src folder.
Put your images (jpg, ...) in there.
Whether you use ImageIO or Toolkit (including getResource),
you must include a leading / in your path to the image file:
Image image = Toolkit.getDefaultToolkit().getImage(getClass().getResource("/resources/agfa_icon.jpg"));
setIconImage(image);
If this code is inside your JFrame class, the image is added to the frame as an icon in your title bar.

This works pretty fine for me.
Just add this after you've created your JFrame.
try {
Image image = new ImageIcon("/icons/image.jpg").getImage();
frame.setIconImage(image);
}catch(Exception e){
System.out.println("Application icon not found");
}

Paste your image icon (fav.png) in the same package first,
Write following code in constructor of JFrame:
setIconImage(Toolkit.getDefaultToolkit().getImage(getClass().getResource("fav.png")));
Note:- fav.png is the name of icon

this.setIconImage(new ImageIcon(getClass().getResource("/iconsfolder/iconsname.jpg")).getImage());
// sets the Global icon for the system
try this code put after this code:
public void displayGUI()
{

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....