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Swing Hacks by Chris Adamson, Joshua Marinacci

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266
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Chapter 7, Text
#50 Auto-Completing Text Fields
HACK
The text field that pops up a window of recently viewed sites is a happy
compromise. It jogs your memory by showing you completion options, and
it saves lots of typing by letting you simply click one of the options and hav-
ing that text inserted immediately into the text field.
A Self-Completing Text Field
This hack takes a JTextField and has it manage a JWindow, which contains a
JList of possible completion values. The real work is done by an inner class
that manages the list of completions and has a
javax.util.regex.Pattern
object to match each potential completion against the field’s current text.
Example 7-4 is what you need to get going.
Example 7-4. A JTextField that manages a pop-up list of completions
import java.awt.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.text.*;
import java.util.*;
import java.util.regex.*;
public class CompletableJTextField extends JTextField
implements ListSelectionListener {
Completer completer;
JList completionList;
DefaultListModel completionListModel;
JScrollPane listScroller;
JWindow listWindow;
public CompletableJTextField (int col) {
super (col);
completer = new Completer( );
completionListModel = new DefaultListModel( );
completionList = new JList(completionListModel);
completionList.setSelectionMode (ListSelectionModel.SINGLE_SELECTION);
completionList.addListSelectionListener (this);
listScroller =
new JScrollPane (completionList,
ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED,
ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
listWindow = new JWindow( );
listWindow.getContentPane( ).add (listScroller);
}
public void addCompletion (String s) {
completer.addCompletion (s); }
Auto-Completing Text Fields #50
Chapter 7, Text
|
267
HACK
public void removeCompletion (String s) {
completer.removeCompletion (s); }
public void clearCompletions (String s ) {
completer.clearCompletions ( ); }
public void valueChanged (ListSelectionEvent e) {
if (e.getValueIsAdjusting( )) { return; }
if (completionList.getModel().getSize( ) == 0) {return;}
listWindow.setVisible (false);
final String completionString =
(String) completionList.getSelectedValue( );
Thread worker = new Thread( ) {
public void run( ) {
setText (completionString);
}
};
SwingUtilities.invokeLater (worker);
}
/** inner class does the matching of the JTextField's
document to completion strings kept in an ArrayList
*/
class Completer implements DocumentListener {
private Pattern pattern;
private ArrayList completions;
public Completer( ) {
completions = new ArrayList( );
getDocument( ).addDocumentListener (this);
}
public void addCompletion (String s) {
completions.add (s);
buildAndShowPopup( );
}
public void removeCompletion (String s) {
completions.remove (s);
buildAndShowPopup( );
}
public void clearCompletions ( ) {
completions.clear( );
buildPopup( );
listWindow.setVisible(false);
}
private void buildPopup( ) {
completionListModel.clear( );
System.out.println ("buildPopup for " + completions.size( ) +
" completions");
Example 7-4. A JTextField that manages a pop-up list of completions (continued)
268
|
Chapter 7, Text
#50 Auto-Completing Text Fields
HACK
Iterator it = completions.iterator( );
pattern = Pattern.compile (getText( ) + ".+");
while (it.hasNext( )) {
// check if match
String completion = (String) it.next( );
Matcher matcher = pattern.matcher (completion);
if (matcher.matches( )) {
// add if match
System.out.println ("matched "+ completion);
completionListModel.add (completionListModel.getSize( ),
completion);
} else {
System.out.println ("pattern " +
pattern.pattern( ) +
" does not match " +
completion);
}
}
}
private void showPopup( ) {
if (completionListModel.getSize( ) == 0) {
listWindow.setVisible(false);
return;
}
// figure out where the text field is,
// and where its bottom left is
java.awt.Point los = getLocationOnScreen( );
int popX = los.x;
int popY = los.y + getHeight( );
listWindow.setLocation (popX, popY);
listWindow.pack( );
listWindow.setVisible(true);
}
private void buildAndShowPopup( ) {
if (getText().length( ) < 1)
return;
buildPopup( );
showPopup( );
}
// DocumentListener implementation
public void insertUpdate (DocumentEvent e) { buildAndShowPopup( ); }
public void removeUpdate (DocumentEvent e) { buildAndShowPopup( ); }
public void changedUpdate (DocumentEvent e) { buildAndShowPopup( ); }
}
}
Example 7-4. A JTextField that manages a pop-up list of completions (continued)

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