JTextField AutoCompletion Error

问题

In this thread, I've found a way to implement AutoComplete feature in a JTextField (and JComboBox, but no issue with this).

When trying to implement this feature in a JTextField it throws some exceptions. The following code will demonstrate the issue. It's so simple, much similar to the way I used with JComboBox, which is working fine.

Can someone help me to find a solution to this.

Here's the code:
(Please note that i'm using swingx)

import javax.swing.JList;
import org.jdesktop.swingx.JXFrame;
import org.jdesktop.swingx.JXTextField;
import org.jdesktop.swingx.autocomplete.AutoCompleteDecorator;

public class ErrorDemo {

    public static void main(String[] args) {
        JXFrame frame = new JXFrame("Error Demo");
        JXTextField field = new JXTextField();
        String[] users = {"aaa", "bbb", "ccc"};
        AutoCompleteDecorator.decorate(new JList(users), field);

        frame.getContentPane().add(field);
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setDefaultCloseOperation(JXFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
}

This is the error message i get :
(it's a bit long :D)

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at org.jdesktop.swingx.autocomplete.ListAdaptor.valueChanged(ListAdaptor.java:76)
    at javax.swing.JList.fireSelectionValueChanged(JList.java:1765)
    at javax.swing.JList$ListSelectionHandler.valueChanged(JList.java:1779)
    at javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:167)
    at javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:147)
    at javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:194)
    at javax.swing.DefaultListSelectionModel.changeSelection(DefaultListSelectionModel.java:388)
    at javax.swing.DefaultListSelectionModel.changeSelection(DefaultListSelectionModel.java:398)
    at javax.swing.DefaultListSelectionModel.setSelectionInterval(DefaultListSelectionModel.java:442)
    at javax.swing.JList.setSelectedIndex(JList.java:2179)
    at javax.swing.JList.setSelectedValue(JList.java:2295)
    at org.jdesktop.swingx.autocomplete.ListAdaptor.setSelectedItem(ListAdaptor.java:98)
    at org.jdesktop.swingx.autocomplete.AutoCompleteDocument.setSelectedItem(AutoCompleteDocument.java:317)
    at org.jdesktop.swingx.autocomplete.AutoCompleteDocument.insertString(AutoCompleteDocument.java:265)
    at javax.swing.text.JTextComponent.replaceSelection(JTextComponent.java:1358)
    at javax.swing.text.DefaultEditorKit$DefaultKeyTypedAction.actionPerformed(DefaultEditorKit.java:859)
    at javax.swing.SwingUtilities.notifyAction(SwingUtilities.java:1636)
    at javax.swing.JComponent.processKeyBinding(JComponent.java:2849)
    at javax.swing.JComponent.processKeyBindings(JComponent.java:2884)
    at javax.swing.JComponent.processKeyEvent(JComponent.java:2812)
    at java.awt.Component.processEvent(Component.java:5815)
    at java.awt.Container.processEvent(Container.java:2058)
    at java.awt.Component.dispatchEventImpl(Component.java:4410)
    at java.awt.Container.dispatchEventImpl(Container.java:2116)
    at java.awt.Component.dispatchEvent(Component.java:4240)
    at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1848)
    at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:697)
    at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:962)
    at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:834)
    at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:661)
    at java.awt.Component.dispatchEventImpl(Component.java:4282)
    at java.awt.Container.dispatchEventImpl(Container.java:2116)
    at java.awt.Window.dispatchEventImpl(Window.java:2429)
    at java.awt.Component.dispatchEvent(Component.java:4240)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)

回答1:

There is no JList involved in your code. I think it should read something like this...

        org.jdesktop.swingx.autocomplete.AutoCompleteDecorator.decorate(field, Arrays.asList(users), false);

If you want to bind a JList to a TextField (so that the text field will update the selection of the JList) you want decorate(JList list, JTextComponent textComponent, ObjectToStringConverter stringConverter) instead...

来源：https://stackoverflow.com/questions/11928999/jtextfield-autocompletion-error