public class AutoCompletableComboBox {
    private String[] keywords = new String[] {
        "",
        "abstract", "assert",       "boolean",  "break",
        "byte",     "case",         "catch",    "char",
        "class",    "const",        "continue", "default",
        "do",       "double",       "else",     "enum",
        "extends",  "final",        "finally",  "float",
        "for",      "goto",         "if",       "implements",
        "import",   "instanceof",   "int",      "interface",
        "long",     "native",       "new",      "package",
        "private",  "protected",    "public",   "return",
        "short",    "static",       "strictfp", "super",
        "switch",   "synchronized", "this",     "throw",
        "throws",   "transient",    "try",      "void",
        "volatile", "while",
    };
 
    private JComboBox comboBox;
    private JLabel label;
 
    public AutoCompletableComboBox() {
        JFrame frame = new JFrame("Auto Complete ComboBox");
        frame.setSize(300, 84);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        
        ((JComponent)frame.getContentPane()).setBorder(new EmptyBorder(10, 10, 10, 10));
        frame.setLayout(new FlowLayout(FlowLayout.LEFT, 10, 0));
        frame.add(createComboBox());
 
        label = new JLabel("");
        frame.add(label);
 
        frame.setVisible(true);
    }
 
    private JComboBox createComboBox() {
        comboBox = new JComboBox(keywords);
 
        // オートコンプリート機能を付加する
        AutoCompleteDecorator.decorate(comboBox);
         
        // イベント処理
        comboBox.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent event) {
                // 選択された文字列をラベルに表示
                String selectedItem = (String)comboBox.getSelectedItem();
                label.setText(selectedItem);
            }
        });
        
        return comboBox;
    }
 
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new AutoCompletableComboBox();
            }
        });
    }
}

        comboBox = new JComboBox(keywords);
 
        // 候補以外の文字列を入力できるようにする
        comboBox.setEditable(true);
 
        // オートコンプリート機能を付加する
        AutoCompleteDecorator.decorate(comboBox);