List method for null returning jComboBox

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Hello! I’m having trouble listing my BD data in a jComboBox. The method I use is as follows:

public void setComboBoxSetorChamado(List<Setor>setores){
    idSetor = new int[setores.size()+1];
    int i = 0;
    //jComboBoxSetorChamado.addItem("");
    idSetor[i] = 0;
    do{
        i++;
        setor = setores.remove(0);
        jComboBoxSetorChamado.addItem(setor.getNome());
        idSetor[i] = setor.getId();
    }while(!setores.isEmpty());
}

I had already used it in other classes and it worked perfectly, but in the class in question returns the following error:

    fev 10, 2015 10:58:27 AM syschamados.view.chamado.ChamadoFormView <init>
    GRAVE: null
    java.lang.NullPointerException
at syschamados.view.chamado.ChamadoFormView.setComboBoxUbsChamado(ChamadoFormView.java:66)
at syschamados.view.chamado.ChamadoFormView.<init>(ChamadoFormView.java:44)
at syschamados.view.chamado.ChamadoView.jButtonNovoChamadoActionPerformed(ChamadoView.java:148)
at syschamados.view.chamado.ChamadoView.access$000(ChamadoView.java:21)
at syschamados.view.chamado.ChamadoView$1.actionPerformed(ChamadoView.java:58)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2346)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6525)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at java.awt.Component.processEvent(Component.java:6290)
at java.awt.Container.processEvent(Container.java:2234)
at java.awt.Component.dispatchEventImpl(Component.java:4881)
at java.awt.Container.dispatchEventImpl(Container.java:2292)
at java.awt.Component.dispatchEvent(Component.java:4703)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4898)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4533)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4462)
at java.awt.Container.dispatchEventImpl(Container.java:2278)
at java.awt.Window.dispatchEventImpl(Window.java:2739)
at java.awt.Component.dispatchEvent(Component.java:4703)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:746)
at java.awt.EventQueue.access$400(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:697)
at java.awt.EventQueue$3.run(EventQueue.java:691)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:86)
at java.awt.EventQueue$4.run(EventQueue.java:719)
at java.awt.EventQueue$4.run(EventQueue.java:717)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:716)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

The line that is the bug is already highlighted. What can I do in this case?

java list

  • Already highlighted? But there’s not even the method the console points to...

  • The method that should be shown is setComboBoxUbsChamado() and if possible, mark line 66 with comments, not symbols >, as it affects the content of the final text.

  • @Gustavocinque in the case of setComboBoxUbsChamado() on the console is a test I had done previously, but the function it performs is virtually the same as the setComboBoxSetorChamado() that is in the code, changing only the entities.

  • Hm... okay, if so. In the case, he must not be finding the instance of ComboBox, tried to give a new JComboBox, or whatever entity it is, before using its methods?

  • I tried that now and the console errors no longer appeared, but what I need (entity listing) did not work. I did two tests: one before the do while (System.out.println("teste cbox1: "+jComboBoxSetorChamado.getSelectedItem());) and another during (System.out.println("teste cbox2: "+jComboBoxSetorChamado.getItemAt(1));). The two returned results, and yet the jComboBox in the form shows nothing.

2 answers

1

Try creating a list of Strings with the values you want and then add in the constructor of JComboBox? See example below:

    List<String> list = new ArrayList<String>();
    list.add("Selecione");
    for (Setor setor : setores) {
        list.add(setor.getNome());
    }
    setorCB = new JComboBox(list.toArray());

To continue accessing the values you want, you can continue with the list of sectors and use a get(position).

  • Don’t you have to initialize this Arraylist? I put it this way in the constructor and it didn’t work (but it also doesn’t give any error in the console).

0

the problem has already been solved. It was in the form components declaration:

public ChamadoFormView(java.awt.Frame parent, boolean modal) {
    super(parent, modal);
    //initComponents();
    UbsController ubsController = new UbsController();
    SetorController setorController = new SetorController();
    TecnicoController tecnicoController = new TecnicoController();
    try{
        setComboBoxUbsChamado(ubsController.list());
        setComboBoxTecnicoChamado(tecnicoController.list());
        setComboBoxSetorChamado(setorController.list());
    }catch(Exception ex){
        Logger.getLogger(ChamadoView.class.getName()).log(Level.SEVERE, null, ex);
    }
}

In the case, the initComponents() was after the try, and that’s what caused the null of jComboBox Now it’s working smoothly.

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