ComboBox doesnt auto-select items

Question

Hello,
my AutoCompleteComboBox doesnt autoselect the first item after initializing and doesnt recognize if user clicks on an item in the list.
I thought every combobox has an actionlistner therefor.
I'm using custom editor-component and model but i dont know where i could have done something wrong.
Any suggestions ?
* AutoCompleteComboBox.java
import java.awt.Component;
import java.util.*;
import javax.swing.*;
import javax.swing.plaf.basic.BasicComboBoxEditor;
import javax.swing.text.*;
public class AutoCompleteComboBox extends JComboBox
     private static final Locale[] INSTALLED_LOCALES = Locale.getAvailableLocales();
     private ComboBoxModel model = null;
     public static void main(String[] args)
          JFrame f = new JFrame("AutoCompleteComboBox");
          f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          AutoCompleteComboBox box = new AutoCompleteComboBox(INSTALLED_LOCALES, false);
          f.getContentPane().add(box);
          f.pack();
          f.setLocationRelativeTo(null);
          f.setVisible(true);
      * Constructor for AutoCompleteComboBox -
      * The Default Model is a TreeSet which is alphabetically sorted and doesnt allow duplicates.
      * @param items
     public AutoCompleteComboBox(Object[] items, boolean caseSensitive)
          super(items);
          model = new ComboBoxModel(items);
          setModel(model);
          setEditable(true);
          setEditor(new AutoCompleteEditor(this, caseSensitive));
      * Constructor for AutoCompleteComboBox -
      * The Default Model is a TreeSet which is alphabetically sorted and doesnt allow duplicates.
      * @param items
     public AutoCompleteComboBox(Vector items, boolean caseSensitive)
          super(items);
          model = new ComboBoxModel(items);
          setModel(model);
          setEditable(true);
          setEditor(new AutoCompleteEditor(this, caseSensitive));
      * Constructor for AutoCompleteComboBox -
      * This constructor uses JComboBox's Default Model which is a Vector.
      * @param caseSensitive
     public AutoCompleteComboBox(boolean caseSensitive)
          super();
          setEditable(true);
          setEditor(new AutoCompleteEditor(this, caseSensitive));
      * ComboBoxModel.java
     public class ComboBoxModel extends DefaultComboBoxModel
           * The TreeSet which holds the combobox's data (ordered no duplicates)
          private TreeSet values = null;
          public ComboBoxModel(List items)
               super();
               this.values = new TreeSet();
               int i, c;
               for (i = 0, c = items.size(); i < c; i++)
                    values.add(items.get(i).toString());
               Iterator it = values.iterator();
               while (it.hasNext())
                    super.addElement(it.next().toString());
          public ComboBoxModel(final Object items[])
               this(Arrays.asList(items));
      * AutoCompleteEditor.java
     public class AutoCompleteEditor extends BasicComboBoxEditor
          private JTextField editor = null;
          public AutoCompleteEditor(JComboBox combo, boolean caseSensitive)
               super();
               this.editor = new AutoCompleteEditorComponent(combo, caseSensitive);
           * overrides BasicComboBox's getEditorComponent to return custom TextField (AutoCompleteEditorComponent)
          public Component getEditorComponent()
               return editor;
      * AutoCompleteEditorComponent.java
     public class AutoCompleteEditorComponent extends JTextField
          JComboBox combo = null;
          boolean caseSensitive = false;
          public AutoCompleteEditorComponent(JComboBox combo, boolean caseSensitive)
               super();
               this.combo = combo;
               this.caseSensitive = caseSensitive;
           * overwritten to return custom PlainDocument which does the work
          protected Document createDefaultModel()
               return new PlainDocument()
                    public void insertString(int offs, String str, AttributeSet a) throws BadLocationException
                         if (str == null || str.length() == 0)
                              return;
                         int size = combo.getItemCount();
                         String text = getText(0, getLength());
                         for (int i = 0; i < size; i++)
                              String item = combo.getItemAt(i).toString();
                              if (getLength() + str.length() > item.length())
                                   continue;
                              if (!caseSensitive)
                                   if ((text + str).equalsIgnoreCase(item))
                                        combo.setSelectedIndex(i);
                                        if (!combo.isPopupVisible())
                                             combo.setPopupVisible(true);
                                        super.remove(0, getLength());
                                        super.insertString(0, item, a);
                                        return;
                                   else if (item.substring(0, getLength() + str.length()).equalsIgnoreCase(text + str))
                                        combo.setSelectedIndex(i);
                                        if (!combo.isPopupVisible())
                                             combo.setPopupVisible(true);
                                        super.remove(0, getLength());
                                        super.insertString(0, item, a);
                                        return;
                              else if (caseSensitive)
                                   if ((text + str).equals(item))
                                        combo.setSelectedIndex(i);
                                        if (!combo.isPopupVisible())
                                             combo.setPopupVisible(true);
                                        super.remove(0, getLength());
                                        super.insertString(0, item, a);
                                        return;
                                   else if (item.substring(0, getLength() + str.length()).equals(text + str))
                                        combo.setSelectedIndex(i);
                                        if (!combo.isPopupVisible())
                                             combo.setPopupVisible(true);
                                        super.remove(0, getLength());
                                        super.insertString(0, item, a);
                                        return;
}regards,
Tim

Answer 1

Hallo Tim,
I didn't thoroughly go through your code, but remembered a less
complex piece of code which does its job nicely. Although its
approach is somewhat different from yours (it doesn't care for
the Combomodel and has no case-sensitivity implemented), it might
nevertheless be of help.import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import javax.swing.text.*;
public class AutoComplete extends JComboBox
                  implements JComboBox.KeySelectionManager {
  private String searchFor;
  private long lap;
  public class CBDocument extends PlainDocument {
    public void insertString(int offset, String str, AttributeSet a)
                         throws BadLocationException {
      if (str==null) return;
      super.insertString(offset, str, a);
      if(!isPopupVisible() && str.length() != 0) fireActionEvent();
  public AutoComplete(Object[] items) {
    super(items);
    lap = new java.util.Date().getTime();
    setKeySelectionManager(this);
    JTextField tf;
    if(getEditor() != null) {
      tf = (JTextField)getEditor().getEditorComponent();
      if(tf != null) {
        tf.setDocument(new CBDocument());
        addActionListener(new ActionListener() {
          public void actionPerformed(ActionEvent evt) {
            JTextField tf = (JTextField)getEditor().getEditorComponent();
            String text = tf.getText();
            ComboBoxModel aModel = getModel();
            String current;
            for(int i = 0; i < aModel.getSize(); i++) {
              current = aModel.getElementAt(i).toString();
              if(current.toLowerCase().startsWith(text.toLowerCase())) {
                tf.setText(current);
                tf.setSelectionStart(text.length());
                tf.setSelectionEnd(current.length());
          break;
  public int selectionForKey(char aKey, ComboBoxModel aModel) {
    long now = new java.util.Date().getTime();
    if (searchFor!=null && aKey==KeyEvent.VK_BACK_SPACE &&
     searchFor.length()>0) {
      searchFor = searchFor.substring(0, searchFor.length() -1);
    else {
//     System.out.println(lap); // Kam nie hier vorbei.
      if(lap + 1000 < now)
        searchFor = "" + aKey;
      else
        searchFor = searchFor + aKey;
    lap = now;
    String current;
    for(int i = 0; i < aModel.getSize(); i++) {
      current = aModel.getElementAt(i).toString().toLowerCase();
      if (current.toLowerCase().startsWith(searchFor.toLowerCase())) return i;
    return -1;
  public void fireActionEvent() {
    super.fireActionEvent();
  public static void main(String arg[]) {
    JFrame f = new JFrame("AutoCompleteComboBox");
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setSize(200,300);
    Container cp= f.getContentPane();
    cp.setLayout(null);
    String[] names= {"Beate", "Claudia", "Fjodor", "Fred", "Friedrich",
     "Fritz", "Frodo", "Hermann", "Willi"};
    JComboBox cBox= new AutoComplete(names);
//    Locale[] locales = Locale.getAvailableLocales();
//    JComboBox cBox= new AutoComplete(locales);
    cBox.setBounds(50,50,100,21);
    cBox.setEditable(true);
    cp.add(cBox);
    f.setVisible(true);
}Greetings
Joerg