Java JComboBox ActionListener crash

Question

I'm getting

Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: -1

when I'm deleting last Item in JComboBox . Anyone knows why?

cb = new JComboBox<String>();
bComboDelete.addActionListener(this);

bComboDelete = new JButton("X"); //deletes item from CB
bComboAccept = new JButton("#");// add an item

ArrayList<String> names = new ArrayList<String>(); //get name, runs with sNumbers
ArrayList<String> sNumbers = new ArrayList<String>();//some String numbers ----> e.g.  [[1, 2, 3],[4, 5, 6]]
ArrayList<Integer> numbers = new ArrayList<Integer>(); //array to temp hold numbers

//***ending code from ActionListener
else if(s == bComboAccept)
{
    sNumbers.add(numbers.toString());
    //System.out.println(sNumbers);
    names.add(tName.getText());//tName is JTextField
    //cb.addItem(tName.getText());

    cb.addItem(new String(tName.getText()));
    cb.setSelectedItem(new String(tName.getText()));
}

else if(s == bComboDelete)
{
    int z = cb.getSelectedIndex();
    //System.out.println(z);
    names.remove(z);
    //System.out.println("Names: "+names);
    sNumbers.remove(z);
    //System.out.println("sNumbers: "+sNumbers);
    cb.removeItem(cb.getSelectedItem());

}

else if(s == cbLista)
{
    System.out.println("cb Action listener!\n--------------");

    Integer i = cb.getSelectedIndex();


    tNames.setText(nazwy.get(i));
    tNumbers.setText("");//also TextField

    numbers.clear();
    numbers=arrayStringToIntegerArrayList(sNumbers.get(i));
    tNumbers.setText(numbers.toString().substring(1, numbers.toString().length()-1));
}

Rest of crash code:

Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: -1 at java.util.ArrayList.elementData(Unknown Source) at java.util.ArrayList.get(Unknown Source) at Okno.actionPerformed(Okno.java:339) at javax.swing.JComboBox.fireActionEvent(Unknown Source) at javax.swing.JComboBox.contentsChanged(Unknown Source) at javax.swing.AbstractListModel.fireContentsChanged(Unknown Source) at javax.swing.DefaultComboBoxModel.setSelectedItem(Unknown Source) at javax.swing.DefaultComboBoxModel.removeElementAt(Unknown Source) at javax.swing.DefaultComboBoxModel.removeElement(Unknown Source) at javax.swing.JComboBox.removeItem(Unknown Source) at Okno.actionPerformed(Okno.java:328) at javax.swing.AbstractButton.fireActionPerformed(Unknown Source) at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source) at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source) at javax.swing.DefaultButtonModel.setPressed(Unknown Source) at javax.swing.plaf.basic.BasicButtonLis tener.mouseReleased(Unknown Source) at java.awt.Component.processMouseEvent(Unknown Source) at javax.swing.JComponent.processMouseEvent(Unknown Source) at java.awt.Component.processEvent(Unknown Source) at java.awt.Container.processEvent(Unknown Source) at java.awt.Component.dispatchEventImpl(Unknown Source) at java.awt.Container.dispatchEventImpl(Unknown Source) at java.awt.Component.dispatchEvent(Unknown Source) at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source) at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source) at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source) at java.awt.Container.dispatchEventImpl(Unknown Source) at java.awt.Window.dispatchEventImpl(Unknown Source) at java.awt.Component.dispatchEvent(Unknown Source) at java.awt.EventQueue.dispatchEventImpl(Unknown Source) at java.awt.EventQueue.access$500(Unknown Source) at java.awt.EventQueue$3.run(Unknown Source) at java.awt.EventQueue$3.run(Unknown Source) at java.security.Access Controller.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at java.awt.EventQueue$4.run(Unknown Source) at java.awt.EventQueue$4.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source) at java.awt.EventQueue.dispatchEvent(Unknown Source) at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source) at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source) at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source) at java.awt.EventDispatchThread.pumpEvents(Unknown Source) at java.awt.EventDispatchThread.pumpEvents(Unknown Source) at java.awt.EventDispatchThread.run(Unknown Source)

Answer 1

Try adding the following modifications...

else if(s == bComboDelete)
{
    int z = cb.getSelectedIndex();

    // -1 means that no item is selected
    if (z > -1) {
        //System.out.println(z);
        names.remove(z);
        //System.out.println("Names: "+names);
        sNumbers.remove(z);
        //System.out.println("sNumbers: "+sNumbers);
        cb.removeItem(cb.getSelectedItem());
    }
}
else if(s == cbLista)
{
    System.out.println("cb Action listener!\n--------------");

    Integer i = cb.getSelectedIndex();

    // -1 means that no item is selected
    if (i > -1) {
        tNames.setText(nazwy.get(i));
        tNumbers.setText("");//also TextField

        numbers.clear();
        numbers=arrayStringToIntegerArrayList(sNumbers.get(i));
        tNumbers.setText(numbers.toString().substring(1, numbers.toString().length()-1));
    }
}

Answer 2

It seems I fixed this. Now code is like this:

I'm too lazy to rename the var to eng. Please ignore System out.

so:

nazwy = names
oceny = numbers
sOceny = sNumbers
cbLista = cb
tNazwa = tNames
tOceny = tNumbers

//----
else if(s == bComboDelete)
    {
        Object o = cbLista.getSelectedItem();

            int z = nazwy.indexOf(o);
            if(z>-1)
            {
            sOceny.remove(z);
            nazwy.remove(z);
            cbLista.removeItemAt(z);
            System.out.println("Oceny w bloku delete(if)"+oceny.toString());
            }
            System.out.println("Oceny w bloku delete(poza if)"+oceny.toString());
    }

    else if(s == cbLista)
    {
        Object o = cbLista.getSelectedItem();

        int z = nazwy.indexOf(o);
        if(z>-1)
        {
        tNazwa.setText(nazwy.get(z));
        oceny.clear();
        oceny=arrayStringToIntegerArrayList(sOceny.get(z));
        tOceny.setText(oceny.toString().substring(1, oceny.toString().length()-1));
        System.out.println("Oceny w bloku CB"+oceny.toString());
        }
        else
        {
            tNazwa.setText("");
            tOceny.setText("");
            oceny.clear();
        }


    }