我在Java Swing应用程序中绝对是新手,我有以下问题。
我有这个简单的 LoginFrame2 类:
package com.test.login;
import java.awt.Container;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTabbedPane;
import net.miginfocom.swt.MigLayout;
import org.jdesktop.application.SingleFrameApplication;
public class LoginFrame2 extends SingleFrameApplication {
public static void main(String[] args) {
System.out.println("DENTRO: LoginFrame() ---> main()");
launch(LoginFrame2.class, args);
}
@Override
protected void startup() {
// TODO Auto-generated method stub
System.out.println("Inside startup()");
JFrame mainFrame = this.getMainFrame(); // main JFrame that represents the Windows
mainFrame.setTitle("XCloud Login");
Container mainContainer = mainFrame.getContentPane(); // main Container into the main JFrame
// JPanel creation and settings of the MigLayout on it:
JPanel externalPanel = new JPanel();
externalPanel.setLayout(new net.miginfocom.swing.MigLayout("fill"));
externalPanel.add(new JLabel("Username"));
mainContainer.add(externalPanel);
mainFrame.add(mainContainer);
}
}
如您所见,我正在使用 JDesktop 框架的 SingleFrameApplication abstrac 类,该类仅向我提供一个主要的 JFrame(此抽象类还负责组件属性注入、退出处理以及以适合简单单帧应用程序的方式保存/恢复会话状态)。
当类被执行时,startUp()方法被执行。
如您所见,我已执行以下操作:
我使用 getMainFrame() 方法获取主 Jframe,并将其引用放入 mainFrame 变量中
我采用主容器(即进入主框架对象)调用getContentPane()方法
然后我创建一个名为 externalPanel 的 JPanel 对象,其中我放置了一个初始化的 JLabel,它将显示一个字符串。
最后,我将 JPanel 对象添加到容器对象,然后尝试将容器添加到主 JFrame 对象。
问题是当我执行这个类时,我收到以下错误消息:
DENTRO: LoginFrame() ---> main()
Inside startup()
8-nov-2013 12.35.23 org.jdesktop.application.Application$1 run
GRAVE: Application class com.test.login.LoginFrame2 failed to launch
java.lang.IllegalArgumentException: adding container's parent to itself
at java.awt.Container.checkAddToSelf(Container.java:418)
at java.awt.Container.addImpl(Container.java:1036)
at java.awt.Container.add(Container.java:957)
at javax.swing.JFrame.addImpl(JFrame.java:540)
at java.awt.Container.add(Container.java:363)
at com.test.login.LoginFrame2.startup(LoginFrame2.java:38)
at org.jdesktop.application.Application$1.run(Application.java:187)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:672)
at java.awt.EventQueue.access$400(EventQueue.java:81)
at java.awt.EventQueue$2.run(EventQueue.java:633)
at java.awt.EventQueue$2.run(EventQueue.java:631)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:642)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
Exception in thread "AWT-EventQueue-0" java.lang.Error: Application class com.test.login.LoginFrame2 failed to launch
at org.jdesktop.application.Application$1.run(Application.java:192)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:672)
at java.awt.EventQueue.access$400(EventQueue.java:81)
at java.awt.EventQueue$2.run(EventQueue.java:633)
at java.awt.EventQueue$2.run(EventQueue.java:631)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:642)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
Caused by: java.lang.IllegalArgumentException: adding container's parent to itself
at java.awt.Container.checkAddToSelf(Container.java:418)
at java.awt.Container.addImpl(Container.java:1036)
at java.awt.Container.add(Container.java:957)
at javax.swing.JFrame.addImpl(JFrame.java:540)
at java.awt.Container.add(Container.java:363)
at com.test.login.LoginFrame2.startup(LoginFrame2.java:38)
at org.jdesktop.application.Application$1.run(Application.java:187)
... 14 more
我认为问题是在其 Jframe 对象中添加了容器对象。但是为什么?据我所知,容器对象是包装在 JFrame 中的对象......问题出在哪里?我该如何解决?
嘟嘟
安德里亚
您正在尝试在此容器中添加容器。问题就在这里
Container mainContainer = mainFrame.getContentPane();
...
mainFrame.add(mainContainer);
这个JFrame mainFrame = this.getMainFrame();
已经有ContentPane
,你再添加一个。每个JFrame都有3个面板 ->glassPane,contentPane和layerdPane。
尝试在mainContainer
中添加元素(已包含在mainFrame
中)。
mainContainer已经从JFrame派生而来。
JFrame mainFrame = this.getMainFrame();
// main JFrame that represents the Windows
mainFrame.setTitle("XCloud Login");
Container mainContainer = mainFrame.getContentPane();
..
mainFrame.add(mainContainer);
mainContainer = mainFrame.getContentPane();
//...
mainFrame.add(mainContainer);//wrong
没有将mainContainer添加回mainFrame的reaqson,并且将子项添加到JFrame通常是完全错误的。
你应该简单地将子项添加到mainContainer,就像你已经做的那样。