JComboBox: adding automatic completion-Cursor position
//Code from: http://www.orbital-computer.de/JComboBox/
/*
Inside JComboBox: adding automatic completion
Author: Thomas Bierhance
thomas@orbital-computer.de
*/
/*
Cursor position
This is really a minor addition and more a question of personal preference. You might have
noticed that the cursor normally is located at the end of the completed text. If you prefer
it to be at the beginning of the selected text try this...
private void highlightCompletedText(int start) {
editor.setCaretPosition(getLength());
editor.moveCaretPosition(start);
}
*/
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;
public class S10CursorPosition extends PlainDocument {
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;
public S10CursorPosition(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) {
if (comboBox.isDisplayable()) comboBox.setPopupVisible(true);
}
});
}
public void remove(int offs, int len) throws BadLocationException {
// return immediately when selecting an item
if (selecting) return;
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) {
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) throws BadLocationException {
// remove all text and insert the completed string
super.remove(0, getLength());
super.insertString(0, text, null);
}
private void highlightCompletedText(int start) {
editor.setCaretPosition(getLength());
editor.moveCaretPosition(start);
}
private void setSelectedItem(Object item) {
selecting = true;
model.setSelectedItem(item);
selecting = false;
}
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());
}
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"});
// 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 S10CursorPosition(comboBox));
// 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();
}
});
}
}
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