我正在测试SwingX AutoCompleteDecorator，我正在使用的代码就是：
import javax.swing.text.JTextComponent;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.JPanel;
import javax.swing.JList;
import org.jdesktop.swingx.autocomplete.*;
public class Test extends JFrame
{
public Test()
{
this.setTitle("Testing");
JPanel pan = new JPanel();
JTextComponent test = new JTextField();
((JTextField)test).setColumns(20);
String[] data = {"one", "two", "three", "four"};
JList dataList = new JList(data);
AutoCompleteDecorator.decorate(dataList, test);
pan.add(test);
this.setContentPane(pan);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setVisible(true);
this.setBounds(280,150,500,200);
}
public static void main(String[] args)
{
Test t = new Test();
}
}
我最终得到一个巨大的运行时错误消息，我不想在线程“AWT-EventQueue-0”中发布关于异常的堆栈跟踪java.lang.NullPointerException：
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at org.jdesktop.swingx.autocomplete.ListAdaptor.valueChanged(ListAdaptor.java:77)
at javax.swing.JList.fireSelectionValueChanged(JList.java:1798)
at javax.swing.JList$ListSelectionHandler.valueChanged(JList.java:1812)
at javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:184)
at javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:164)
at javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:211)
at javax.swing.DefaultListSelectionModel.changeSelection(DefaultListSelectionModel.java:405)
at javax.swing.DefaultListSelectionModel.changeSelection(DefaultListSelectionModel.java:415)
at javax.swing.DefaultListSelectionModel.setSelectionInterval(DefaultListSelectionModel.java:459)
at javax.swing.JList.setSelectedIndex(JList.java:2212)
at javax.swing.JList.setSelectedValue(JList.java:2362)
at org.jdesktop.swingx.autocomplete.ListAdaptor.setSelectedItem(ListAdaptor.java:99)
at org.jdesktop.swingx.autocomplete.AutoCompleteDocument.setSelectedItem(AutoCompleteDocument.java:355)
at org.jdesktop.swingx.autocomplete.AutoCompleteDocument.insertString(AutoCompleteDocument.java:303)
at javax.swing.text.JTextComponent.replaceSelection(JTextComponent.java:1386)
at javax.swing.text.DefaultEditorKit$DefaultKeyTypedAction.actionPerformed(DefaultEditorKit.java:884)
at javax.swing.SwingUtilities.notifyAction(SwingUtilities.java:1664)
at javax.swing.JComponent.processKeyBinding(JComponent.java:2879)
at javax.swing.JComponent.processKeyBindings(JComponent.java:2926)
at javax.swing.JComponent.processKeyEvent(JComponent.java:2842)
at java.awt.Component.processEvent(Component.java:6282)
at java.awt.Container.processEvent(Container.java:2229)
at java.awt.Component.dispatchEventImpl(Component.java:4861)
at java.awt.Container.dispatchEventImpl(Container.java:2287)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1895)
at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:762)
at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:1027)
at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:899)
at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:727)
at java.awt.Component.dispatchEventImpl(Component.java:4731)
at java.awt.Container.dispatchEventImpl(Container.java:2287)
at java.awt.Window.dispatchEventImpl(Window.java:2719)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:729)
at java.awt.EventQueue.access$200(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:688)
at java.awt.EventQueue$3.run(EventQueue.java:686)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.awt.EventQueue$4.run(EventQueue.java:702)
at java.awt.EventQueue$4.run(EventQueue.java:700)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:699)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
我错过了什么？
答案 0 :(得分：4)
这是一个错误：罪魁祸首是使用双参数方法使用JList的项目装饰textComponent时的null ObjectToStringConverter：
public static void decorate(JList list, JTextComponent textComponent) {
decorate(list, textComponent, null);
}
快速解决方法是使用三参数方法并传入默认转换器：
JTextComponent test = new JTextField(20);
String[] data = {"one", "two", "three", "four"};
JList dataList = new JList(data);
AutoCompleteDecorator.decorate(dataList, test, ObjectToStringConverter.DEFAULT_IMPLEMENTATION);
提交Issue #1570 - 修订版本＃4305
Morning Musings（可以安全地忽略： - ）
技术原因是构造函数链接不正确：插入默认值应由do-it-all构造函数处理（或者它应该抛出NPE）
public ListAdaptor(JList list, JTextComponent textComponent) {
this(list, textComponent, ObjectToStringConverter.DEFAULT_IMPLEMENTATION);
}
public ListAdaptor(JList list, JTextComponent textComponent, ObjectToStringConverter stringConverter) {
this.list = list;
this.textComponent = textComponent;
this.stringConverter = stringConverter;
// when a new item is selected set and mark the text
list.addListSelectionListener(this);
}
根本原因是转换器所有权的微妙转变：它的通常所有者是处理autoComplete的自定义文档，此文档针对null保护自己。使用JList变体，它的ListAdaptor不习惯这种负担......转换不是不正确的（事实上，确切的方式），只是引入了一个容易被忽视的轻微不一致。
答案 1 :(得分：0)
AutoCompleteDecorator.decorate(dataList, test, false)
只需添加错误设置
或就像这些
boolean strictMatching = false;
AutoCompleteDecorator.decorate(UName,items,strictMatching);