GroupLayout 中的 IllegalStateException

Question

我的面板使用GroupLayout：

GroupLayout layout = new GroupLayout(this);
this.setLayout(layout);

layout.setHorizontalGroup(
    layout.createParallelGroup()
        .addComponent(title_panel)
        .addComponent(subtitle_panel)
    );

layout.setVerticalGroup(
    layout.createSequentialGroup()
        .addComponent(title_panel)
        .addComponent(subtitle_panel)
    );

即使我同时定义了水平组和垂直组，它仍然给了我一个

java.lang.IllegalStateException

但并非总是如此。有时它会这样做，有时它不会。即使有这个异常，我的 GUI 也能正常工作并显示我想要的。

我想我有一个答案。当我第一次显示面板所在的框架时，我没有这个异常。但是，当我第二次显示它时，它给了我这个例外。这就像程序在框架的两次启动之间保留了我的 groupLayout 的一部分，或者类似的东西。

这很令人沮丧，即使它在这个异常的情况下仍然有效 ^^' 我不喜欢我自己的代码拖累我！

这是我得到的错误示例（derp 是我的项目的名称，Panel 是从 JPanel 继承的类）：

Exception in thread "AWT-EventQueue-0" java.lang.IllegalStateException: derp.Panel[,0,0,0x0,invalid,layout=java.awt.FlowLayout,alignmentX=0.0,alignmentY=0.0,border=,flags=9,maximumSize=,minimumSize=,preferredSize=] is not attached to a horizontal group
at javax.swing.GroupLayout.checkComponents(GroupLayout.java:1086)
at javax.swing.GroupLayout.prepare(GroupLayout.java:1040)
at javax.swing.GroupLayout.layoutContainer(GroupLayout.java:910)
at java.awt.Container.layout(Container.java:1503)
at java.awt.Container.doLayout(Container.java:1492)
at java.awt.Container.validateTree(Container.java:1688)
at java.awt.Container.validateTree(Container.java:1697)
at java.awt.Container.validateTree(Container.java:1697)
at java.awt.Container.validate(Container.java:1623)
at javax.swing.RepaintManager$2.run(RepaintManager.java:679)
at javax.swing.RepaintManager$2.run(RepaintManager.java:677)
at java.security.AccessController.doPrivileged(Native Method)
at     java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at javax.swing.RepaintManager.validateInvalidComponents(RepaintManager.java:676)
at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1650)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:721)
at java.awt.EventQueue.access$200(EventQueue.java:100)
at java.awt.EventQueue$3.run(EventQueue.java:682)
at java.awt.EventQueue$3.run(EventQueue.java:680)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:691)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)
juin 27, 2013 4:39:35 PM io.socket.IOConnection transportMessage

Answer 1

我认为问题出在这两行代码，“this”指的是你的类的实例，GroupLayout的父级必须是Swing容器，比如面板

GroupLayout layout = new GroupLayout(this);
this.setLayout(layout);

试试这样的

JComponent panel = ...;
GroupLayout layout = new GroupLayout(panel);
panel.setLayout(layout);