I am having an issue with this AutoCompletion class that I am using. The behavior that I wish to achieve is as follows:
1. As the user is typing in the JComboBox, I dont want an actionEvent to occur. I only want the actionEvent to trigger when the user hits the enter key or selects an item with the mouse.
2. As the user is typing in the JComboBox, I want the popup menu to display the highlighted item at the top of the menu instead of the bottom.
Here is the AutoCompletion class:
import java.awt.event.*;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import javax.swing.*;
import javax.swing.text.*;
public class AutoCompletion extends PlainDocument
{
private static final long serialVersionUID = -5904225455924280749L;
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;
boolean hidePopupOnFocusLoss;
boolean hitBackspace = false;
boolean hitBackspaceOnSelection;
KeyListener editorKeyListener;
FocusListener editorFocusListener;
public AutoCompletion(final JComboBox comboBox)
{
this.comboBox = comboBox;
model = comboBox.getModel();
comboBox.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
if (!selecting)
{
highlightCompletedText(0);
}
}
});
comboBox.addPropertyChangeListener(new PropertyChangeListener()
{
public void propertyChange(PropertyChangeEvent e)
{
if (e.getPropertyName().equals("editor"))
{
configureEditor((ComboBoxEditor) e.getNewValue());
}
if (e.getPropertyName().equals("model"))
{
model = (ComboBoxModel) e.getNewValue();
}
}
});
editorKeyListener = new KeyAdapter()
{
public void keyPressed(KeyEvent e)
{
if (comboBox.isDisplayable())
{
comboBox.setPopupVisible(true);
}
hitBackspace = false;
switch (e.getKeyCode())
{
// determine if the pressed key is backspace (needed by the remove method)
case (KeyEvent.VK_BACK_SPACE) :
{
hitBackspace = true;
hitBackspaceOnSelection = editor.getSelectionStart() != editor.getSelectionEnd();
break;
}
// ignore delete key
case (KeyEvent.VK_DELETE) :
{
//e.consume();
//comboBox.getToolkit().beep();
setText("");
comboBox.setPopupVisible(false);
break;
}
}
}
};
// 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 gaining focus
editorFocusListener = new FocusAdapter()
{
public void focusGained(FocusEvent e)
{
highlightCompletedText(0);
}
public void focusLost(FocusEvent e)
{
// Workaround for Bug 5100422 - Hide Popup on focus loss
if (hidePopupOnFocusLoss)
{
comboBox.setPopupVisible(false);
}
}
};
configureEditor(comboBox.getEditor());
// Handle initially selected object
Object selected = comboBox.getSelectedItem();
if (selected != null)
{
setText(selected.toString());
}
highlightCompletedText(0);
}
public static void enable(JComboBox comboBox)
{
// has to be editable
comboBox.setEditable(true);
// change the editor's document
new AutoCompletion(comboBox);
}
void configureEditor(ComboBoxEditor newEditor)
{
if (editor != null)
{
editor.removeKeyListener(editorKeyListener);
editor.removeFocusListener(editorFocusListener);
}
if (newEditor != null)
{
editor = (JTextComponent) newEditor.getEditorComponent();
editor.addKeyListener(editorKeyListener);
editor.addFocusListener(editorFocusListener);
editor.setDocument(this);
}
}
public void remove(int offs, int len) throws BadLocationException
{
// return immediately when selecting an item
if (selecting)
{
return;
}
if (hitBackspace)
{
// user hit backspace => move the selection backwards
// old item keeps being selected
if (offs > 0)
{
if (hitBackspaceOnSelection)
{
offs--;
Object object = (String)lookupItem(getText(0, offs));
setSelectedItem(object);
setText(object.toString());
}
}
else
{
// User hit backspace with the cursor positioned on the start => beep
//comboBox.getToolkit().beep(); // when available use: UIManager.getLookAndFeel().provideErrorFeedback(comboBox);
setText("");
comboBox.setPopupVisible(false);
}
highlightCompletedText(offs);
}
else
{
super.remove(offs, len);
}
}
public void insertString(int offs, String str, AttributeSet a) throws BadLocationException
{
// return immediately when selecting an item
if (selecting) return;
// insert the string into the document
super.insertString(offs, str, a);
// lookup and select a matching item
Object item = lookupItem(getText(0, getLength()));
if (item != null)
{
// commented out to remove auto selection when typing
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);
}
setText(item.toString());
// select the completed part
highlightCompletedText(offs+str.length());
}
private void setText(String text)
{
try
{
// remove all text and insert the completed string
super.remove(0, getLength());
super.insertString(0, text, null);
}
catch (BadLocationException e)
{
throw new RuntimeException(e.toString());
}
}
private void highlightCompletedText(int start)
{
editor.setCaretPosition(getLength());
editor.moveCaretPosition(start);
}
private void setSelectedItem(Object item)
{
selecting = true;
model.setSelectedItem(model.getElementAt(model.getSize() - 1));
model.setSelectedItem(item);
selecting = false;
}
private Object lookupItem(String pattern)
{
//Object selectedItem = model.getSelectedItem();
Object selectedItem = model.getElementAt(0);
// 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 (currentItem != null && 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());
}
}
I tried to take care of requirement number two by doing this:
model.setSelectedItem(model.getElementAt(model.getSize() - 1));
model.setSelectedItem(item);
But it causes some performance issues that I cannot have in my application.
It automatically triggers two actionEvents when I only need one. And as for requirement number 1, I have no idea how to attack that issue. If someone can lead me in the right direction that would be awesome.
Oh and heres how to work with the class:
public static void main(String[] args)
{
//set up JFrame...
JComboBox comboBox = new JComboBox(stringArray);
AutoCompletion.enable(comboBox);
//more code...
}