JComboBox: adding automatic completion-Binay Lookup 2 : ComboBox « Swing Components « Java
JComboBox: adding automatic completion-Binay Lookup 2
//Code from: http://www.orbital-computer.de/JComboBox/
/*
Inside JComboBox: adding automatic completion
Author: Thomas Bierhance
thomas@orbital-computer.de
*/
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;
import java.lang.reflect.Field;
import javax.swing.plaf.basic.BasicComboBoxUI;
public class S20BinaryLookup 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;
boolean hidePopupOnFocusLoss;
boolean hitBackspace=false;
boolean hitBackspaceOnSelection;
public S20BinaryLookup(final JComboBox comboBox) {
this.comboBox = comboBox;
model = comboBox.getModel();
editor = (JTextComponent) comboBox.getEditor().getEditorComponent();
editor.setDocument(this);
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);
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();
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
editor.addFocusListener(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);
}
});
setPrototypeValue();
// Handle initially selected object
Object selected = comboBox.getSelectedItem();
if (selected!=null) setText(selected.toString());
highlightCompletedText(0);
}
public void setPrototypeValue() {
JList list = getListBox();
setPrototypeValue(getPrototypeValue(list), list);
}
void setPrototypeValue(Object value, JList list) {
comboBox.setPrototypeDisplayValue(value);
list.setPrototypeCellValue(value);
}
Object getPrototypeValue(JList list) {
Object prototypeValue=null;
double prototypeWidth=0;
ListCellRenderer renderer = comboBox.getRenderer();
for (int i=0, n=model.getSize(); i<n; i++) {
Object value = model.getElementAt(i);
java.awt.Component c = renderer.getListCellRendererComponent(list, value, i, false, false);
double width = c.getPreferredSize().getWidth();
if (width>prototypeWidth) {
prototypeWidth=width;
prototypeValue=value;
}
}
return prototypeValue;
}
JList getListBox() {
JList listBox;
try {
Field field = JComponent.class.getDeclaredField("ui");
field.setAccessible(true);
BasicComboBoxUI ui = (BasicComboBoxUI) field.get(comboBox);
field = BasicComboBoxUI.class.getDeclaredField("listBox");
field.setAccessible(true);
listBox = (JList) field.get(ui);
} catch (NoSuchFieldException nsfe) {
throw new RuntimeException(nsfe);
} catch (IllegalAccessException iae) {
throw new RuntimeException(iae);
}
return listBox;
}
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--;
} else {
// User hit backspace with the cursor positioned on the start => beep
comboBox.getToolkit().beep(); // when available use: UIManager.getLookAndFeel().provideErrorFeedback(comboBox);
}
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) {
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(item);
selecting = false;
}
private Object binaryLookup(String pattern) {
int bottom=0, top=model.getSize()-1;
int pos=0;
Object item=null;
// search for a matching item
while (bottom<=top) {
pos = (bottom + top) >> 1;
item=model.getElementAt(pos);
int compare = compareStartIgnoreCase(item.toString(), pattern);
if (compare==0) {
break;
} else if (compare>0) {
bottom=pos+1;
} else {
top=pos-1;
}
}
// if no item matches bottom is greater than top
if (bottom>top) return null;
// search for the _first_ matching item
for (int i=bottom; i<pos; i++) {
Object anItem=model.getElementAt(i);
if (startsWithIgnoreCase(anItem.toString(), pattern)) {
return anItem;
}
}
return item;
}
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;
}
Object item = binaryLookup(pattern);
return item;
}
// checks if str1 starts with str2 - ignores case
private boolean startsWithIgnoreCase(String str1, String str2) {
return str1.toUpperCase().startsWith(str2.toUpperCase());
}
private static int compareStartIgnoreCase(String str1, String str2) {
char[] ch1 = str1.toCharArray();
char[] ch2 = str2.toCharArray();
for (int i=0, n=ch2.length<ch1.length?ch2.length:ch1.length; i<n; i++) {
int diff = Character.toUpperCase(ch2[i])-Character.toUpperCase(ch1[i]);
if (diff != 0) {
return diff;
}
}
if (ch1.length<ch2.length) return 1;
return 0;
}
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);
// change the editor's document
new S20BinaryLookup(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();
}
});
}
}
