Autocomplete JComboBox

Two other developers here have been able to solve the problem. They sorted out the custom code that ran the searches.

class Principal {
private static void createAndShowGUI() {
    // the combo box (add/modify items if you like to)
    JComboBox comboBox = new JComboBox(new Object[] {"Ester", "Jordi", "Jordina", "Jorge", "Sergi", "1040506070", "SISTEMAS DA INFORMAÇÃO", "SAL", "GOIANIA", "COORDENACAO DE RH"});
    // has to be editable
    comboBox.setEditable(true);
    // get the combo boxes editor component
    JTextComponent editor = (JTextComponent) comboBox.getEditor().getEditorComponent();
    // change the editor's document
    editor.setDocument(new SearchableComboBox(comboBox));
    comboBox.setSelectedIndex(-1);

    // create and show a window containing the combo box
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(3);
    frame.getContentPane().add(comboBox);
    frame.pack(); frame.setVisible(true);
}


public static void main(String[] args) {
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
        public void run() {
            createAndShowGUI();
        }
    });}

and

class SearchableComboBox extends PlainDocument {

private static final long serialVersionUID = 4956303094169423395L;

JComboBox comboBox;
ComboBoxModel model;
JTextComponent editor;
// flag to indicate if setSelectedItem has been called
// subsequent calls to remove/insertString should be ignored
boolean selecting=false;
StringBuilder caracteresParaBusca = new StringBuilder();
int teclaAtual = 0;

public SearchableComboBox(final JComboBox comboBox) {
    this.comboBox = comboBox;
    model = comboBox.getModel();
    editor = (JTextComponent) comboBox.getEditor().getEditorComponent();

    comboBox.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            if (!selecting) highlightCompletedText(0);
        }
    });
    editor.addKeyListener(new KeyAdapter() {
        public void keyPressed(KeyEvent e) {    
            teclaAtual = e.getKeyCode();        
            String digitado = e.getKeyChar() + "";              
            if(digitado.matches("[A-Za-z0-9 -.,/]")){
                caracteresParaBusca.append(e.getKeyChar());  
            }

            if(e.getKeyCode() == KeyEvent.VK_ENTER) {
                try {
                    insertString(0,caracteresParaBusca.toString(), null);
                } catch (BadLocationException e1) {
                    e1.printStackTrace();
                } 
            }

            if (comboBox.isDisplayable()) comboBox.setPopupVisible(true);
        }
    });
}

public void remove(int offs, int len) throws BadLocationException {
    if (selecting) return;
    super.remove(offs, len);
}

public void insertString(int offs, String str, AttributeSet a) throws BadLocationException {
    if (selecting) return;
    super.insertString(offs, str, a);
    Object item = null;

    if(teclaAtual == KeyEvent.VK_ENTER){
        item = lookupItem(caracteresParaBusca.toString());
        caracteresParaBusca.delete(0, caracteresParaBusca.length());
    } else {
        return;
    }

    if (item != null) {
        setSelectedItem(item);
   } else {
        item = comboBox.getSelectedItem();
        offs = offs-str.length();
        comboBox.getToolkit().beep(); // when available use: UIManager.getLookAndFeel().provideErrorFeedback(comboBox);

    }
    setText(item.toString());
    //highlightCompletedText(offs+str.length());
}

private void setText(String text) throws BadLocationException {
    super.remove(0, getLength());
    super.insertString(0, text, null);
}

private void highlightCompletedText(int start) {
    editor.setSelectionStart(start);
    editor.setSelectionEnd(getLength());
}

private void setSelectedItem(Object item) {
    selecting = true;
    model.setSelectedItem(item);
    selecting = false;
}

private Object lookupItem(String pattern) {
    String buscar = pattern;
    Object selectedItem = model.getSelectedItem();
    if(selectedItem != null) {
        buscar = caracteresParaBusca.toString();
    }

    for (int i = 0, n = model.getSize(); i < n; i++) {
        Object currentItem = model.getElementAt(i);
        // current macth with the pattern?
        if (qualquerParte(currentItem.toString(), buscar)) {
            return currentItem;
        }
       }

    return null;
}

private boolean qualquerParte(String str1, String str2) {
    return str1.toUpperCase().contains(str2.toUpperCase());
}