public class AutoCompleteJComboBoxer extends PlainDocument {
private final JComboBox comboBox;
private ComboBoxModel model;
private JTextComponent editor;
private boolean hidePopupOnFocusLoss;
public AutoCompleteJComboBoxer(JComboBox comboBox) {
this.comboBox = comboBox;
comboBox.setEditable(true);
model = comboBox.getModel();
editor = (JTextComponent) comboBox.getEditor().getEditorComponent();
editor.setDocument(this);
// Bug 5100422 on Java 1.5: Editable JComboBox won't hide popup when tabbing out
hidePopupOnFocusLoss = System.getProperty("java.version").startsWith("1.5");
// Highlight whole text when focus gets lost
editor.addFocusListener(new FocusAdapter() {
@Override
public void focusLost(FocusEvent e) {
highlightCompletedText(0);
// Workaround for Bug 5100422 - Hide Popup on focus loss
if (hidePopupOnFocusLoss) AutoCompleteJComboBoxer.this.comboBox.setPopupVisible(false);
}
});
// Highlight whole text when user hits enter
editor.addKeyListener(new KeyAdapter() {
@Override
public void keyPressed(java.awt.event.KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_ENTER) {
highlightCompletedText(0);
} else if (e.getKeyCode() == KeyEvent.VK_ESCAPE) {
AutoCompleteJComboBoxer.this.comboBox.setSelectedIndex(0);
AutoCompleteJComboBoxer.this.editor.setText(AutoCompleteJComboBoxer.this.comboBox.getSelectedItem().toString());
highlightCompletedText(0);
}
}
});
// Handle initially selected object
Object selected = comboBox.getSelectedItem();
if (selected != null) editor.setText(selected.toString());
}
@Override
public void insertString(int offs, String str, AttributeSet a) throws BadLocationException {
// construct the resulting string
String currentText = getText(0, getLength());
String beforeOffset = currentText.substring(0, offs);
String afterOffset = currentText.substring(offs, currentText.length());
String futureText = beforeOffset + str + afterOffset;
// lookup and select a matching item
Object item = lookupItem(futureText);
if (item != null) {
comboBox.setSelectedItem(item);
} else {
// keep old item selected if there is no match
item = comboBox.getSelectedItem();
// imitate no insert (later on offs will be incremented by str.length(): selection won't move forward)
offs = offs-str.length();
// provide feedback to the user that his input has been received but can not be accepted
comboBox.getToolkit().beep(); // when available use: UIManager.getLookAndFeel().provideErrorFeedback(comboBox);
}
// remove all text and insert the completed string
super.remove(0, getLength());
super.insertString(0, item.toString(), a);
// if the user selects an item via mouse the the whole string will be inserted.
// highlight the entire text if this happens.
if (item.toString().equals(str) && offs==0) {
highlightCompletedText(0);
} else {
highlightCompletedText(offs+str.length());
// show popup when the user types
comboBox.setPopupVisible(true);
}
}
private void highlightCompletedText(int start) {
editor.setCaretPosition(getLength());
editor.moveCaretPosition(start);
}
private Object lookupItem(String pattern) {
Object selectedItem = model.getSelectedItem();
// only search for a different item if the currently selected does not match
if (selectedItem != null && startsWithIgnoreCase(selectedItem.toString(), pattern)) {
return selectedItem;
} else {
// iterate over all items
for (int i=0, n=model.getSize(); i < n; i++) {
Object currentItem = model.getElementAt(i);
// current item starts with the pattern?
if (startsWithIgnoreCase(currentItem.toString(), pattern)) {
return currentItem;
}
}
}
// no item starts with the pattern => return null
return null;
}
// checks if str1 starts with str2 - ignores case
private boolean startsWithIgnoreCase(String str1, String str2) {
return str1.toUpperCase().startsWith(str2.toUpperCase());
}
}
