Plz help with this Exception "AWT-EventQueue-0" error

[sQu3aKy]

Hi guys,

I am developing an instant messaging using "smack API" and Openfire as the server. I have a login GUI which contains:
-username txtfield and password passwordfield
-and a login button.
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And Main GUI which contains:
-Menubar:File, Help
-status label with statusdropdownlist (available etc)
-JScroller with JTree to show the users "jst like msn, yahoo etc)
-and a logout button
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I am able to login to the client using the correct username/password then once i click login (in the Login GUI) it will take me to the Main GUI and show this error, I am not sure wat is causing this as i kept checkin time n time again so would appreciate if someone could offer a help.
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The loginbutton actionperformed code:

 private void loginbtnActionPerformed(java.awt.event.ActionEvent evt) {                                         
        if(evt.getSource()==loginbtn){
            try {
                loginbtn();
            } catch (XMPPException ex) {
                System.out.println(ex);
            }

        }

 public void loginbtn()throws XMPPException {
        user = usernametxt.getText().trim().toLowerCase();
        char [] input = passwordtxt.getPassword();
        String password = String.valueOf(input).toLowerCase();

        if(user.isEmpty() || password.isEmpty()) {
              errorlbl.setText("Please type in a valid username and password");
          }else if(user.contains(" ") || password.contains(" ")){
              errorlbl.setText("Username and password cannot contain spaces");
          }else{
                connection.connect();
                connection.login(user, password);
                this.dispose();
                new MainUI().setVisible(true);
          }
    }
}

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The error i get after clicking Login button:

run:
Exception in thread "AWT-EventQueue-0" java.lang.Error: java.lang.reflect.InvocationTargetException
        at org.jdesktop.application.ApplicationAction.actionFailed(ApplicationAction.java:859)
        at org.jdesktop.application.ApplicationAction.noProxyActionPerformed(ApplicationAction.java:665)
        at org.jdesktop.application.ApplicationAction.actionPerformed(ApplicationAction.java:698)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
        at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
        at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:272)
        at java.awt.Component.processMouseEvent(Component.java:6263)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)
        at java.awt.Component.processEvent(Component.java:6028)
        at java.awt.Container.processEvent(Container.java:2041)
        at java.awt.Component.dispatchEventImpl(Component.java:4630)
        at java.awt.Container.dispatchEventImpl(Container.java:2099)
        at java.awt.Component.dispatchEvent(Component.java:4460)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4574)
        at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4238)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4168)
        at java.awt.Container.dispatchEventImpl(Container.java:2085)
        at java.awt.Window.dispatchEventImpl(Window.java:2478)
        at java.awt.Component.dispatchEvent(Component.java:4460)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
Caused by: java.lang.reflect.InvocationTargetException
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.jdesktop.application.ApplicationAction.noProxyActionPerformed(ApplicationAction.java:662)
        ... 27 more
Caused by: java.lang.IllegalStateException: Already logged in to server.
        at org.jivesoftware.smack.XMPPConnection.login(XMPPConnection.java:385)
        at org.jivesoftware.smack.XMPPConnection.login(XMPPConnection.java:349)
        at ChatClientMain.LoginUI.loginbtn(LoginUI.java:207)
        ... 32 more

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Thanks in advance

[Eranga]

Did you look at the complete error message ?

Caused by: java.lang.IllegalStateException: Already logged in to server.

[sQu3aKy]

Thank u Eranga...I am new to java that is why and i couldn't spot that but once again rlly appreciate thnx alot.

[SOLVED]

[Eranga]

So did you fix the problem? That's on what I want to help you, and I want you to fix the problem yourself looking at the error and so on.

[sQu3aKy]

Yeh, i did manage to fix...after u pointed out once again thnks and sry for wasting ur time with this silly question :)

[Eranga]

You are welcome, and no worries at all. Mistake are really helpful you to learn stuff in correct way. Good luck. :)