Re: Exception in thread "main" java.lang.NullPointerException

TurboPT · #11 17-Jun-2009, 17:38

Refer back to post #9, I already gave you a hint, but if you still get stuck, post another reply.

idrismca · #12 18-Jun-2009, 10:48

thanx for yr help turbo.... i did get yr hint but the prob is if i initialize like this

JAVA Code:

    private JPanel mainPanel= new JPanel();
    private JTextField _username= new JTextField();
    private JPasswordField _password= new JPasswordField();
    private JButton _loginButton= new JButton();
.................................

the executable jar does run from the command prompt but only a minimized blank frame comes up with nothing on it... and an error on the console

Code:

Exception in thread "main" java.lang.NullPointerException
        at com.ardenasset.ui.taxlot.forms.TaxLotToolUI.main(Unknown Source)

Also I when i try running it from intelliJ the KeyListener n action listeners do not respond because I guess i initialized "new".....

Where am i wrong? i cant figure out.... is it that because i m using intelliJ and in the "TaxLotTool.form" GUI i have used GridBagLayout(IntelliJ) for the layout manager in some panels including the main panel?

I have even included the forms_rt.jar of intelliJ in the jar's classpath.

TurboPT · #13 18-Jun-2009, 13:32

1. I don't see (unless I missed it) where the controls are added to the UI? That would explain the 'blank frame'.

2. For the exception, it appears that 'mainPanel' is not initialized, so that could still 'bomb' main, at this statement:

JAVA Code:

         frame.setContentPane( gui.mainPanel );  // mainPanel not initialized?

In the constructor, I didn't suggest that you place a try around every listener (doesn't hurt anything), I was referring to the first statement in the constructor for addShutdownHook() because the Java API mentions three different exceptions that could possibly be thrown by that call.

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