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POWhy does InvokeLater cause my JFrame not to display correctly?
 

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  1. POWhy does InvokeLater cause my JFrame not to display correctly?
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    <p>Ok I've read an searched all over the web, and I've not found the solution to my problem yet, perhaps I'm missing something simple, hence here I am...</p> <p>I've got a rather large project, that handles work orders for a repair business. It's all database connected, many many pages of code, and classes. But i just added a short bit of code to the front end that essentially checks for new messages in our notes area. </p> <p>Anyway, I display a simple <em>JFrame</em> with two <em>JLabel</em>s while a separate thread queries the database. This all happens at the start of the program. The problem is my little "please wait" <em>JFrame</em> comes up with its frame but no guts, no background, and no <em>JLabel</em>s, during the wait (which is the rest of the program loading, not the database thread), afterwords it displays, but by then its missing its point. </p> <p>I wrote the following example program. It displays a simple <em>JFrame</em> (CheckingMessagesGUI: a <em>JFrame</em> with two <em>JLabel</em>s, nothing more) sleeps for 5 sec then displays the Example (main program) <em>JFrame</em>, then instantly closes (<code>System.exit(0)</code>) in this example, of course my real program goes on to do a lot more. What I found is that <code>invokeLater</code> seems to be causing the problem. Once the sleep timer runs out the window will display, but the code to display it was given before the <code>Thread.sleep</code> command, and should have been done in that order correct?</p> <p>My question is why does <code>invokeLater</code> cause my <em>JFrame</em> not to display correctly? </p> <p>Its my understanding that the purpose of <code>invokeLater</code> is so that the items run on the correct AWT event thread, which would make me think that this window would get painted correctly. Anyway I'm sure I'm missing something obvious. I commented out the <code>invokeLater</code> part in the code below, and it runs correctly, if you put it back it doesn't...</p> <p>Many thanks in advance.</p> <pre><code>package javaapplication6; public class Example extends javax.swing.JFrame { public Example() { System.out.println("Example started"); setBounds(100,100,200,200); System.out.println("cmGUI instantiated"); CheckingMessagesGUI cmGUI = new CheckingMessagesGUI(); System.out.println("Set cmGUI visible"); cmGUI.setVisible(true); cmGUI.validate(); try { System.out.println("timer started"); Thread.sleep(5000); System.out.println("timer done"); } catch(InterruptedException e){ } System.exit(0); } public static void main(String[] args) { /*java.awt.EventQueue.invokeLater(new Runnable() { @Override public void run() { */ System.out.println("Started"); System.out.println("example Instantiated"); Example example = new Example(); System.out.println("example visible"); example.setVisible(true); /* } }); */ } } </code></pre> <p>UPDATE: To clarify, I realize <code>Thread.sleep()</code> will block everything, but shouldn't my CheckingMessagesGUI already have been fully drawn before I call sleep? That is the issue.</p>
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