Swing Hacks

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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 ...