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How can you keep a JPanel from closing on System.exit(0)

I have a program that I am terminating with the System.exit(0); command.
When this happens the JPanel closes. I would like it to rename open so I can view the state at termination. Is there a way of keeping the Jpanel open or is there a better command than System.exit()?
not sure why a down vote I asked a simple question and someone answered it. I can't do it that way so try something else. Going to use a true false to test where to enter the simulation loop.

regarding:
Is there a way of keeping the Jpanel open or is there a better command than System.exit()?
The best solution: Don't call System.exit(...). Why? Because System.exit(0) closes the JVM, and so all Java processes running on that JVM will shut down when System.exit(0) is called.
As for "better command", that all depends on your need. If you just want to close a window such as a JDialog, then call myWindow.setVisible(false);. If you want to close it and release resources, then myWindow.dispose();.
Note: I suspect that you might have multiple windows open, perhaps multiple JFrames. If so, I strongly urge you to read: The Use of Multiple JFrames, Good/Bad Practice?
You also posted in comments:
I would like to keep the Jpanel open, but stop the simulation from running. I need to stop the Sim when certain conditions are met. so I wrote a stop()
So your question is in fact an XY Problem where you ask how to solve a specific code problem (keep a JPanel open after calling System.exit(0)) when the best solution is to use a completely different approach. Better that you tell us the overall problem that you're trying to solve rather than how you're currently trying to solve it, because System.exit isn't going to be part of the best solution.
Likely the best solution is to well separate your simulation model from its view (the GUI), to be able to give the model functionality that allows it to stop without closing down the JVM -- impossible for me to say how given our current level of knowledge about your problem -- and then reflect the stopping of the model in the view, again without shutting down the system.
The key to all of this will lie in the details of your current program, including the logic that underpins your simulation, and if you need more specific and likely more helpful answers, you're again going to want to improve your question, providing us with much more specific information about your code, your problem and with posting of pertinent code, preferably as a minimal example program.

Have you tried an approach similar to:
Do something when the close button is clicked on a JFrame
Basically, you're grabbing the Window closing event by setting a listener on the frame
You can then .dispose() the appropriate jpanel/frame if you want
JFrame is window and JPanel is a container. The moment the JPanel instance loses its reference, it will be garbage collected
How can JPanel be disposed after the panel has been removed from the JFrame
Disposing JFrame by clicking from an inner JPanel
import javax.swing.JOptionPane;
/*Some piece of code*/
frame.addWindowListener(new java.awt.event.WindowAdapter() {
#Override
public void windowClosing(java.awt.event.WindowEvent windowEvent) {
//delete this code if you want and replace with .dispose() or anything
if (JOptionPane.showConfirmDialog(frame,
"Are you sure to close this window?", "Really Closing?",
JOptionPane.YES_NO_OPTION,
JOptionPane.QUESTION_MESSAGE) == JOptionPane.YES_OPTION){
//choose to close JVM here if you want
System.exit(0);
}
}
});

Here's a way, by overriding the SecurityManager for the JVM:
//set your security manager
static{
SecurityManager s = new DontCloseOnExitSecurityManager();
System.setSecurityManager(s);
}
static class DontCloseOnExitSecurityManager extends SecurityManager{
public void checkExit(int code){
//here you can put a check to see if you really do want to close - like if the JFrame is still open.
if(/*do some check*/ 13 == code)
super.checkExit(code);
throw new SecurityException("13 is unlucky, you shouldn't system exit on it.");
}
}
}
You'll need to find an appropriate place to put it in, and also how to do your checks (in checkExit).
Apologies for inaccuracies, I'm not in front of an IDE to test this right now.

When I dispose and reopen a JFrame, it doesn't show anything

I have a fairly simple Java Application I created with JFrames. There is more than one JFrame in my program. I have a menu launching at the beginning of the program. After going through the menu, I have the menu JFrame disposed.
The main JFrame has a menu button that should launch the exact same menu at a later time. However, when you launch the menu from inside of the ActionListener (when you press the menu button), the JFrame doesn't launch properly. None of the components show up and colors are off.
However, when the menu is launched from outside of the ActionListener, the JFrame shows up perfectly. I have tried multiple methods to fix this, but none of them have worked.
My full program code is available by clicking here.
The main class is "LetsMultiply5.java". This class also sets up the ActionListener.
The JFrame causing the problem is "MenuWindow.java".
"LetsMultiply5.java" calls the "Booter.java" class, which then calls the "MenuWindow.java".
"MainWindow.java" is the JFrame that has the "Menu" button.
For proof, "SpeedModer.java" calls the menu window after it has been disposed, and works.
================================EDIT================================
Also, I'd like to let you know that I realize my code is a little bit messy. I am not sure how else to write the code for this program.
I am forced to use Thread.sleep(x); because the Swing timers aren't what I am looking for. The Swing timers activate an ActionListener when the timer goes off. I need a system that will wait a second before continuing on with the code.
I realize that the while (repeater==0) loop with ActionListeners inside of it seems crazy, but that was the only way I could get it to work. If I put a single ActionListener and just had the while loop do no code inside of it, nothing happens when I press the button.
I would, as MadProgrammer mentioned:
Advice: Scrap your current approach and start again.
However, the way that I have my program currently coded is the only way that I know how to get what I need to do done. I read the tutorials, but still don't know how to improve the code in the way that you told me.
I thank everyone for trying to tell me to improve my bad "Java grammar", but as far as I am concerned, I am not going to continue this program for the next 20 years and make my millions off of it.
I have looked at the Swing timers before and I understand the whole new Timer(speed, this); concept, but I don't understand how this would make my code any better.
If anyone would like to show me how to fix my ActionListeners or Thread.sleep(x); lines, please tell me. Thank you.

You're blocking the Event Dispatching Thread with Thread.sleep(3000); - Don't do this, it will prevent the UI from been painted
See Concurrency in Swing for more details about the problem and How to use Swing Timers for a possible solution
You may also want to consider having a look at The Use of Multiple JFrames, Good/Bad Practice? and consider using CardLayout or JTabbedPane
If you need to block the user temporarily (to display a error message or gather important details), consider using a modal JDialog. See How to Make Dialogs for more details

Any way to delay PaintComponent?

I've read through lots of the threads on paintComponent here, most of which making the point that it either is never or almost never necessary (or possible) to choose when paintComponent is called.
In my program, however, sometimes (only sometimes) paintComponent gets called before some of the objects it needs to paint have finished initializing or even sometimes before they've been created, triggering warnings- JOptionPane pop-ups, which surprisingly do not show any of the text they were hard-coded to display in their "message" area. I've read in other places that it's something to do with the EDT, and I've looked into some parts of that but I'm just getting confused. If the main purpose of the EDT is to update the gui, and by default pretty much everything will run in the EDT, then could I tell the program to run all the initialization and update functions in a different thread(s), which I somehow forcibly make run before the EDT runs?
What I'd ideally like to have happen is for paintComponent to wait until a certain point in my code to be run (after a bunch of update functions, regardless of what happens to the screen. After it does get called, it is followed by a pause in which relatively little is going on ( I had been using Thread.sleep() inside a while loop ) and which lasts until the user clicks something - at which point all the necessary functions are run again, followed by paintComponent afterwards, then the sleep() while loop, etc.
From what I understand, I think what I want isn't really possible, so my question is: Do you guys have any ideas of how to get around this?
EDIT:
So essentially the program is a college course planner, intended to make it easier for someone to plan out by semester all the courses they have to take before graduation, move those courses around (if possible), and see how all the courses are connected (prerequisites and such). When the program starts, it loads the list of necessary courses from a text file, then loads info about each course from a bunch of individual text files, and arranges them according to their prerequisites. Courses with no prerequisites go in the first semester, courses whose prerequisites have all been added to the first semester get added to the second, and so on until all the courses have been added. When paintComponent runs, it calls a function that assume all of each course's prerequisites exist on the schedule, and if it finds otherwise, it throws an error and displays a JOptionPane message box. When this happens during a normal run of the program (like if I manually add a course before adding its prerequisites), that all works and displays correctly. But sometimes that message box pops up when only some of the courses have been loaded (meaning control is still in the main constructor) and when it does so, the actual string message doesn't show up - only the actual pane, title and ok button do. Heres the line where I display the error box, so you can know that I'm not trying to display a string variable which has the potential of being empty.
JOptionPane.showMessageDialog(this,
"Course couldn't be loaded, partially >loaded\ncourses have been removed.",
"Error",
JOptionPane.OK_OPTION);
It is the "Course couldn't...been removed." part that doesn't get displayed. This is the only JOptionPane I display with the title "Error".
This post mentioned what sounds like the same thing happening, except I'm not using any of the things that poster had to fix. So possibly it's irrelevant but I'll add it just in case. JOptionPane.showMessageDialog() shows but without any message?
But to step back a bit, because that box popped up before all the courses had been added, it means that paintComponent was somehow called in the middle of the relevant JPanel's constructor, before a bunch of things had been initialized. I added a bunch of println() statements to make sure that that is true. Is it normal for that to happen, and if so, is there a way to fix it without simply using Andrew Thompson's advice?
After thinking though it a bit, I think that because the project is 3200 lines long and relies to a huge extent on text files, I'm really not sure how to ( or if I can) make a SSCCE for it..
If any specific pieces would be helpful I'll gladly add those but if this problem isn't clearly some standard issue I'm getting wrong, then I'll just add that flag and keep looking for bugs.
Thanks for your help

Declare a flag as a class attribute. Check it in the paint method. Change it at the end of the initialization.
class XandYandZ extends JComponent {
boolean initializationFinished = false;
public XandYandZ() {
// long initialisation..
initializationFinished = true;
}
public void paintComponent(Graphics g) {
if (!initializationFinished) return;
// .. paint ..

JPanel overriding revalidate()

For my program I have a JPane that as the game progresses it adds labels to the panel, however the only way I can make the panels show up is by using add(label) then revalidating and vice versa for removing labels.
My problem is that once it gets to the point that I have more than 40 labels on the screen the revalidate has to process too many things, so how can I override the revalidate(), ether works, so that it only revalidates the specific component that was added, and not every component on the screen. I know there is a loop somewhere within the revalidate() method that will run through a loop of all components, but I just can not for the life of me find it. I would like to be able to call revalidate(component-here) or validate (component-here) and have it only update that specific component.
I know there are other ways of writing this program but I am only interested in how to override revalidate() so no "you could have redone your whole code this way which should only take you like 6 hours >.<".
http://www.fileserve.com/file/jFdQ6nv/FINAL_PROJECT.zip a link to my eclipse project, if anyone who wants to help would like to see what im actually talking abouyt

I just tried this example. Adding 1000 text areas only takes a second, and updates are instant. Labels go even faster. You might want to look at something else slowing it down.
Also, you could look at CellRendererPane. It overrides invalidate() to do nothing.
public void invalidate() {}

Cursor blinks in two fields (JTextField)

Hello? anyone had a problem like: cursor blinking in more than one field at a time?
In my case the following happens: When you double click on a field JTextField, opens a JDialog, so
after closing this, the focus is directed back to the field clicked before opening the screen.
What happens is that after performing this action, two fields are flashing at the same time (usually the first field
screen, as well as the field in which efetuei double click).
This medium is random, there are cases in which it does not occur.
When debugging the inner class Handler, contained within the class DefaultCaret more specifically the actionPerformed method, realized
that: time is a field, and time is another, which are precisely the fields that are flashing (q seems obvious I know). but they are
the own inner classes of Java that are calling the method.
When passing over the field using the Tab, the cursor false, vanishes.
I'm using JDK 6
I returned the focus within the invokeLater(), but not solved. Now both synchronized flash
The first JComponent focusable is one of the fields that flashing improperly
I'm using my own FocusTraversalPolicy, does that may be influencing? The funny thing is that there is no treatment particularly strange about my class.
I noticed that the standard Java class, using a method within the Syncronized getFirstComponent(), but added the same control, but still is not ok

Actually it's Focus issue for me.
Normally when JTextComponent looses Focus setCaretVisible(false) / setSelectionVisible(false) is called and when Focus gained opposite thing happens.
After closing JDialog try to return Focus inside invokeLater(). Also check what's the first focusable JComponent in the JDialog's parent.

This situation occurs because the project I'm developing is quite large, so do not get small examples of implementation
The project has many components, Tables and Container's, which require focus through at the same time.
It turns out that Swing, put in a queue for execution, a lot of threads, and then dispatching them going, and while he did not finish running it, you can cram grabFocus() or requestFocus(), which does not cry, the first he has to finish everything and then run my request focus.
Resolved palliatively this situation, using the Swing SwingUtilities.invokeLater(...);
Thanks for the tips.