Problem in java swing programming

Hello
I am developing one project. I which i put one main menu from which user choose various options.
One of the option is associating students with the batch.
As user choose this option, it opens one frame in which user get one comobox containing list of batches that are already announced in the system.
As user choose any of these batch number, i want that frame shows the one JLabel control and one JList control shows list of candidates registered for the course for which selected batch has announced.
For that i put one penal in the frame which implements ActionListener interface and registered this panel as the ActionListener of this batch combobox. As user choose any of the batch from this combobox in the actionPerformed method i call repaint method.
In the paintComponent method of panel i add two control one JLabel and one JList .
But my panel or frame does not show these control.
What should i do.
I also want to know i develop projects in JDK1.2 will it runs on JDK1.3 or JDK1.4
Because i was using JDK1.2 but it had deleted and i now i am unable to get that version.

Here is some good advice. Take time to download a new version of the SDK, it will help you do things more quickly.
To your problem, I believe it is a matter of switching components within the application. To switch components, you need to use the container.remove(Component c) method, and then use container.add(Component c)Finally you need to validate the container and repaint it to show your newly added component. So in all
container.remove(somecomponent);
container.add(anothercomponent);
container.validate();
container.repaint();Hope this helps one way or the other
ICE

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Problem with java swing button and loop

Problem with java swing button and loop
I�m using VAJ 4.0. and I�m doing normal GUI application. I have next problem.
I have in the same class two jswing buttons named start (ivjGStart) and stop (ivjGStop) and private static int field named Status where initial value is 0. This buttons should work something like this:
When I click on start button it must do next:
Start button must set disenabled and Stop button must set enabled and selected. Field status is set to 1, because this is a condition in next procedure in some loop. And then procedure named IzvajajNeprekinjeno() is invoked.
And when I click on stop button it must do next:
Start button must set enabled and selected and Stop button must set disenabled.
Field status is set to 0.
This works everything fine without loop �do .. while� inside the procedure IzvajajNeprekinjeno(). But when used this loop the start button all the time stay (like) pressed. And this means that a can�t stop my loop.
There is java code, so you can get better picture:
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ivjGStart.setEnabled(true);
ivjGStart.setSelected(true);
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} catch (Exception e) {
/** procedure IzvajajNeprekinjeno() */
public void IzvajajNeprekinjeno() { //RunLoop
try {
int zamik = 2000; //delay
do {
Thread.sleep(zamik);
PreberiDat(); //procedure
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} catch (Exception e) {
So, I'm asking what I have to do, that start button will not all the time stay pressed? Or some other aspect of solving this problem.
Any help will be appreciated.
Best regards,
Tomi

This is a multi thread problem. When you start the gui, it is running in one thread. Lets call that GUI_Thread so we know what we are talking about.
Since java is task-based this will happen if you do like this:
1. Button "Start" is pressed. Thread running: GUI_Thread
2. Event gStart_ActionEvents() called. Thread running: GUI_Thread
3. Method IzvajajNeprekinjeno() called. Thread running: GUI_Thread
4. Sleep in method IzvajajNeprekinjeno() on thread GUI_Thread
5. Call PreberiDat(). Thread running: GUI_Thread
6. Check status. If == 1, go tho 4. Thread running: GUI_Thread.
Since the method IzvajajNeprekinjeno() (what does that mean?) and the GUI is running in the same thread and the event that the Start button has thrown isn't done yet, the program will go on in the IzvajajNeprekinjeno() method forever and never let you press the Stop-button.
What you have to do is do put either the GUI in a thread of its own or start a new thread that will do the task of the IzvajajNeprekinjeno() method.
http://java.sun.com/docs/books/tutorial/uiswing/index.html
This tutorial explains how to build a multi threaded gui.
/Lime

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Hi Sir,
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817439 wrote:
Could you please tell me under which category I should post this query. I could not find JAVA Swing section anywhetre in forum home.Steps
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you could charge for homework assignments :)) // I would
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does the poster want a pass / credit / distinction ?? the code will vary and so will the cost....

Problem with Java Mail Program

Hi Everyone...
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You need to be identified by stmp server :
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Read JavaMail Faq please!

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with in inner class; needs to be declared final; then when i declare it final it says <identifier expected>. Could some one please help me. thanx.

Please post code within code tags (press the "code" button).
Why are you using an inner class? Simplify:
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Hello
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Check this out :
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if I don't find a better solution I'll try your 2nd option but what do you mean by "combo" update?
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Chazza wrote:
Perhaps you need to change your keyboard layout in Xorg?
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I have tried to change the keyboard layout from "en" to "cn", but it is still not work.
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Last edited by Dilingg (2015-05-15 16:18:43)

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