从另一个类调用Java GUI方法[关闭]

Question

我对编程很新，我试图将一个GUI方法从一个不同的类调用到我的主类但是遇到了麻烦，当从GUI类运行程序时一切正常但是当我运行主类我得到的时候控制台中的错误消息。

这些是我得到的错误

Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: adding container's parent to itself
at java.awt.Container.checkAddToSelf(Unknown Source)
at java.awt.Container.addImpl(Unknown Source)
at java.awt.Container.add(Unknown Source)
at mathsQuiz3_1_1.MathsQuiz_3_1_1_Main$1.run(MathsQuiz_3_1_1_Main.java:16)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$500(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$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)

这是主要的课程

public static void main(String[] args) {

     SwingUtilities.invokeLater(new Runnable() {
        public void run() {

            Maths_Quiz_3_1_1_GUI GUIObject = new Maths_Quiz_3_1_1_GUI();
            JFrame frame = new JFrame();
            GUIObject.setDefaultCloseOperation(Maths_Quiz_3_1_1_GUI.EXIT_ON_CLOSE);
            GUIObject.getContentPane().add(GUIObject);
            GUIObject.pack();
            GUIObject.setVisible(true);
        }
    });
}

继承了GUI类

package mathsQuiz3_1_1;

public class Maths_Quiz_3_1_1_GUI extends JFrame {

/**
 * Launch the application.
 */
public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                Maths_Quiz_3_1_1_GUI frame = new Maths_Quiz_3_1_1_GUI();
                frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

public Maths_Quiz_3_1_1_GUI() {

    JPanel contentPane;
    JPanel pnlStartScreen = new JPanel();
    JPanel pnlAnswerScreen = new JPanel();
    JPanel pnlQuestionResult = new JPanel();
    JPanel pnlEndScreen = new JPanel();

    ButtonGroup btngrpQuestionType = new ButtonGroup();

    /**
     * JFrame
     */

    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 1100, 700);
    contentPane = new JPanel();
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    setContentPane(contentPane);
    contentPane.setLayout(new CardLayout(0, 0));

我删除了其余的代码，只是向jframe添加了更多元素。

我看过用户遇到类似问题的this thread并尝试实施解决方案，但仍然没有运气。任何人都可以提供的任何帮助都会有所帮助，因为我是编程新手，并且不确定如何使用GUI和调用方法。

Answer 1

嗯...

做的组合

线程“AWT-EventQueue-0”中的异常java.lang.IllegalArgumentException：将容器的父级添加到自身

和

 GUIObject.getContentPane().add(GUIObject);

按门铃？