Autocomplete in JComboBox

Question

Hey folks,
I want to enable autocomplete in a simple editable JComboBox (like in MS access). I've been searching google and now here, but cant seem to find anything. Does anyone have any idea how to implement this?
Furthermore: i cant seem to capture keys being pressed in the editable combobox. It wont fire keypressed/released/typed events when i type in the box :( Are any events fired at all when one types a(ny) key in a JComboBox?? (that is, every time a key is pressed, so the the actionPerformed when you hit enter won't do)
Any help greatly appreciated!

Answer 1

Hello,
my old attempt could help you:
package temp;
* AutoCompleteComboBox.java
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
          public AutoCompleteEditor(JComboBox combo, boolean caseSensitive)
               super();
               editor = new AutoCompleteEditorComponent(combo, caseSensitive);
      * 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)||item.substring(0, getLength() + str.length()).equalsIgnoreCase(text + str))
                                        combo.setSelectedIndex(i);
                                         super.remove(0, getLength());
                                        super.insertString(0, item, a);
                                        return;
                              else if (caseSensitive)
                                   if ((text + str).equals(item)||item.substring(0, getLength() + str.length()).equals(text + str))
                                        combo.setSelectedIndex(i);
                                        super.remove(0, getLength());
                                        super.insertString(0, item, a);
                                        return;
}The relevant part is the insertString method, i must admit not really simple.
Regards,
Tim