JComboBox: adding automatic completion-Handling focus loss : ComboBox « Swing Components « Java
JComboBox: adding automatic completion-Handling focus loss
//Code from: http://www.orbital-computer.de/JComboBox/
/*
Inside JComboBox: adding automatic completion
Author: Thomas Bierhance
thomas@orbital-computer.de
*/
/*
Handling focus loss
Another situation that needs highlighting of the complete text is when the user switches to another gui control (e.g. pressing the tabulator key). Otherwise the partial selection would still be there when the user returns to the combo box. Highlighting the complete text when the combo box loses focus could be a solution. However, switching the focus via mouse will not lead to the desired behaviour then: The cursor gets positioned by the mouse click and therefore the prior selection is removed. A better solution is to highlight the text when the focus is gained.
// Highlight whole text when gaining focus
editor.addFocusListener(new FocusAdapter() {
public void focusGained(FocusEvent e) {
highlightCompletedText(0);
}
});
The popup list is hidden automatically when the user hits enter on most JDKs. The latest Java 1.5 release from Sun contains a bug and keeps the popup list visible. The popup list can't be hidden for all JDK versions as this might lead to malfunctioning. A workaround could look like 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 gaining focus
editor.addFocusListener(new FocusAdapter() {
[...]
public void focusLost(FocusEvent e) {
// Workaround for Bug 5100422 - Hide Popup on focus loss
if (hidePopupOnFocusLoss) comboBox.setPopupVisible(false);
}
});
*/
import javax.swing.*;
import javax.swing.text.*;
import java.awt.event.*;
public class S12FocusLost extends PlainDocument {
JComboBox comboBox;
ComboBoxModel model;
JTextComponent editor;
boolean hidePopupOnFocusLoss;
public S12FocusLost(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() {
public void focusLost(FocusEvent e) {
highlightCompletedText(0);
// Workaround for Bug 5100422 - Hide Popup on focus loss
if (hidePopupOnFocusLoss) S12FocusLost.this.comboBox.setPopupVisible(false);
}
});
// Highlight whole text when user hits enter
editor.addKeyListener(new KeyAdapter() {
public void keyPressed(java.awt.event.KeyEvent e) {
if (e.getKeyCode() == e.VK_ENTER) {
highlightCompletedText(0);
}
}
});
// Handle initially selected object
Object selected = comboBox.getSelectedItem();
if (selected != null) editor.setText(selected.toString());
}
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());
}
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"});
new S12FocusLost(comboBox);
// create and show a window containing the combo box
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(3);
frame.getContentPane().setLayout(new java.awt.FlowLayout());
frame.getContentPane().add(comboBox);
frame.getContentPane().add(new JTextField("I wan't more focus!"));
frame.pack(); frame.setVisible(true);
}
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}
