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

  1. #1
    Junior Member
    Join Date
    Nov 2012
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    Default Exception in thread "main" java.lang.NullPointerException

    Hello, I really hopeless and I feel like this is my last chance to fix that, before I will have to send this to my teacher.
    I'm getting this error:
    Exception in thread "main" java.lang.NullPointerException
    at ui.PanelBatohu.<init>(PanelBatohu.java:33)
    at ui.Gui.init(Gui.java:107)
    at ui.Gui.<init>(Gui.java:68)
    at main.Start.main(Start.java:25)

    Legend: Doing graphic interface for this one little java game.
    Batoh= Bag(container in game)
    zaregistruj pozorovatele(register observer)

    first error line is:

    [30] public PanelBatohu(Batoh batoh) {
    [31] super();
    [32] this.batoh = batoh;
    [33] batoh.zaregistrujPozorovatele(this);
    [34] this.aktualizuj(batoh);
    [36] this.setBorder(BorderFactory.createTitledBorder("V ěci v batohu:"));
    [37] this.setVisible(true);

    second error line is:

    [107]panelBatohu = new PanelBatohu(hra.getBatoh());
    [108] hlavniOknoFrame.add(panelBatohu, BorderLayout.WEST);[LIST=1]

    third error line:

    [65]public Gui(Hra hra) {
    [66] this.hra = hra;
    [67] initMenu();
    [68] init();

    fourth error line:

    [23]public static void main(String[] args) {
    [24] if (args.length == 0) {
    [25] Gui grafika = new Gui(new Hra());

  2. #2
    Crazy Cat Lady KevinWorkman's Avatar
    Join Date
    Oct 2010
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    Default Re: Exception in thread "main" java.lang.NullPointerException

    Look at the line throwing the NPE. You are dereferencing something that is null on that line. What is it? You can use a debugger or some print statements to figure it out.
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