SwingX :一个关键字和几个建议

Question

我想创建一个带有建议列表的JTextField (比如谷歌、netbeans……)，换句话说，当我在我的JTextField中输入一个单词时，会显示一个列表……所以我试了一下：

import java.awt.BorderLayout;
import java.awt.HeadlessException;
import javax.swing.*;
import org.jdesktop.swingx.autocomplete.AutoCompleteDecorator;

/**
 *
 * @author marwen
 */
public class Test_swingx extends JFrame {

    public Test_swingx(String title) throws HeadlessException {
        JPanel pan = new JPanel();
        pan.setLayout(new BorderLayout());
        JTextField jtf = new JTextField(20);
        String[] tab = {"marwen", "marven", "mawww", "mamma", "ddd", "dddddd", "ppppp"};
        JList list = new JList(tab); //data has type Object[]
        AutoCompleteDecorator.decorate(list, jtf);
        pan.add(jtf, BorderLayout.NORTH);
        pan.add(list, BorderLayout.CENTER);

        setTitle(title);
        setContentPane(pan);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        pack();
        setVisible(true);
    }

    public static void main(String[] args) {
        java.awt.EventQueue.invokeLater(new Runnable() {

            public void run() {
                Test_swingx tsx = new Test_swingx("helloo swingx");
            }
        });
    }
}

但是我得到了这个错误：

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:1798)
at javax.swing.JList$ListSelectionHandler.valueChanged(JList.java:1812)
at    javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:184)
at  javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:164)
at  javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:211)
at javax.swing.DefaultListSelectionModel.changeSelection(DefaultListSelectionModel.java:405)
at javax.swing.DefaultListSelectionModel.changeSelection(DefaultListSelectionModel.java:415)
at javax.swing.DefaultListSelectionModel.setSelectionInterval(DefaultListSelectionModel.java:459)
at javax.swing.JList.setSelectedIndex(JList.java:2212)
at javax.swing.JList.setSelectedValue(JList.java:2362)
at  org.jdesktop.swingx.autocomplete.ListAdaptor.setSelectedItem(ListAdaptor.java:98)
at  org.jdesktop.swingx.autocomplete.AutoCompleteDocument.setSelectedItem(AutoCompleteDocument.java:313)

正常工作，我不明白文档中是否有错误？https://pirlwww.lpl.arizona.edu/resources/guide/software/SwingX/org/jdesktop/swingx/autocomplete/AutoCompleteDecorator.html

谢谢你的帮助。

Answer 1

给出下面的代码：

• http://www.jarvana.com/jarvana/view/org/swinglabs/swingx/1.6.1/swingx-1.6.1-sources.jar!/org/jdesktop/swingx/autocomplete/ListAdaptor.java?format=ok

抛出异常的代码行是：

getTextComponent().setText(stringConverter.getPreferredStringForItem(list.getSelectedValue()));

在这种情况下，stringConverter为null。这就解决了这个问题：

AutoCompleteDecorator.decorate(list, jtf, ObjectToStringConverter.DEFAULT_IMPLEMENTATION);

如果你还没有看过，看看这篇文章：

• http://today.java.net/pub/a/today/2007/07/19/adding-auto-completion-to-swing-comboboxes.html