（已回答）如何在不抛出异常的情况下强行在活动的 JTextField 中设置文本？

Question

每当我尝试在字段具有焦点时设置内容时，JTextField 的 SetText 方法都会引发异常。我需要改变它，因为我想输入非常精确的字符数，一旦达到字符数，就需要清除该字段，同时仍然保持焦点，以便可以立即添加下一组字符，而无需按任何按钮。

我尝试创建一个静态方法，它会在每次填满时从头开始重新创建文本字段，从而允许每次递归地重新生成该字段。该方法根本没有做任何事情。作为参考，基本上这个程序中的所有内容都是静态的，因为它是一个非常简单的应用程序，我基本上只想访问 "main".

中的每个重要变量

尝试在字段具有焦点时设置文本显示如下：

Exception in thread "AWT-EventQueue-0" java.lang.IllegalStateException: Attempt to mutate in notification
    at javax.swing.text.AbstractDocument.writeLock(Unknown Source)
    at javax.swing.text.AbstractDocument.replace(Unknown Source)
    at javax.swing.text.JTextComponent.setText(Unknown Source)
    at onlypack.ProgramMain.insertUpdate(ProgramMain.java:118)
    at javax.swing.text.AbstractDocument.fireInsertUpdate(Unknown Source)
    at javax.swing.text.AbstractDocument.handleInsertString(Unknown Source)
    at javax.swing.text.AbstractDocument.insertString(Unknown Source)
    at javax.swing.text.PlainDocument.insertString(Unknown Source)
    at javax.swing.text.AbstractDocument.replace(Unknown Source)
    at javax.swing.text.JTextComponent.replaceSelection(Unknown Source)
    at javax.swing.text.DefaultEditorKit$DefaultKeyTypedAction.actionPerformed(Unknown Source)
    at javax.swing.SwingUtilities.notifyAction(Unknown Source)
    at javax.swing.JComponent.processKeyBinding(Unknown Source)
    at javax.swing.JComponent.processKeyBindings(Unknown Source)
    at javax.swing.JComponent.processKeyEvent(Unknown Source)
    at java.awt.Component.processEvent(Unknown Source)
    at java.awt.Container.processEvent(Unknown Source)
    at java.awt.Component.dispatchEventImpl(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.KeyboardFocusManager.redispatchEvent(Unknown Source)
    at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(Unknown Source)
    at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(Unknown Source)
    at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(Unknown Source)
    at java.awt.DefaultKeyboardFocusManager.dispatchEvent(Unknown Source)
    at java.awt.Component.dispatchEventImpl(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Window.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
    at java.awt.EventQueue.access0(Unknown Source)
    at java.awt.EventQueue.run(Unknown Source)
    at java.awt.EventQueue.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue.run(Unknown Source)
    at java.awt.EventQueue.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)

Answer 1

you can't modify the document from inside a Document LIstener

正确，需要等Document进入接受输入状态

实现此目的的一种方法是将您的代码包装在 DocumentListener 中的 SwingUtilties.invokeLater() 中。这会将代码放在 Event Dispatch Thread 的末尾，它将在文档完成自身更新后执行。

另一个选项，它不使用 DocumentListener，而是使用 DocumentFilter。这会在将文本添加到文档之前拦截文本。因此，您可以在输入指定数量的字符后简单地清除文档。阅读 Implement a DocumentFilter 上的 Swing 教程部分了解更多信息。

（已回答）如何在不抛出异常的情况下强行在活动的 JTextField 中设置文本？

(Answered) How do you forcibly set text in an active JTextField without throwing an exception?

java

swing

user-interface

jtextfield