erreur: Исключение в потоке "AWT-EventQueue-0" java .lang.IllegalArgumentException: добавление окна в контейнер

Question

Я хочу добавить JFrame из другого класса с именем: Home к другому Jframe в классе Dashboard, когда я нажимаю на кнопку Home, должно быть содержимое класса Home в mainPnale, но когда я его запускаю, он показывает эту ошибку : Исключение в потоке "AWT-EventQueue-0" java .lang.IllegalArgumentException: добавление окна в контейнер, поэтому, пожалуйста, помогите мне, спасибо alote

это панель инструментов Интерфейс, когда я нажимаю кнопку Home, должен импортировать Panel из класса Home, как второй пи c, это интерфейс класса Home

это функция при нажатии кнопки home из класса Dashboard:

private void panelHomeMouseClicked(java.awt.event.MouseEvent evt) {                                       



    panelcontent.removeAll();
    Home he = new Home();
    panelcontent.add(he);


}  

и это класс Home:

/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package project;

/**
 *
 * @author MR-INT
 */
public class Home extends javax.swing.JFrame {

/**
 * Creates new form Home
 */
public Home() {
    initComponents();
}

/**
 * This method is called from within the constructor to initialize the form. WARNING: Do NOT modify this code. The content of this method is always regenerated by the Form Editor.
 */
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    panelMainContent3 = new javax.swing.JPanel();
    lblcontent3 = new javax.swing.JLabel();
    jRadioButtonMenuItem1 = new javax.swing.JRadioButtonMenuItem();
    home_form1 = new javax.swing.JPanel();
    jButton2 = new javax.swing.JButton();
    jLabel1 = new javax.swing.JLabel();
    jButton1 = new javax.swing.JButton();
    jButton3 = new javax.swing.JButton();

    panelMainContent3.setPreferredSize(new java.awt.Dimension(300, 350));

    lblcontent3.setText("hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh");

    javax.swing.GroupLayout panelMainContent3Layout = new javax.swing.GroupLayout(panelMainContent3);
    panelMainContent3.setLayout(panelMainContent3Layout);
    panelMainContent3Layout.setHorizontalGroup(
        panelMainContent3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(panelMainContent3Layout.createSequentialGroup()
            .addGap(375, 375, 375)
            .addComponent(lblcontent3)
            .addContainerGap(436, Short.MAX_VALUE))
    );
    panelMainContent3Layout.setVerticalGroup(
        panelMainContent3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(panelMainContent3Layout.createSequentialGroup()
            .addGap(153, 153, 153)
            .addComponent(lblcontent3)
            .addContainerGap(181, Short.MAX_VALUE))
    );

    jRadioButtonMenuItem1.setSelected(true);
    jRadioButtonMenuItem1.setText("jRadioButtonMenuItem1");

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

    jButton2.setText("jButton2");

    jLabel1.setText("Welcome to the main home");

    jButton1.setText("jButton1");

    jButton3.setText("jButton3");

    javax.swing.GroupLayout home_form1Layout = new javax.swing.GroupLayout(home_form1);
    home_form1.setLayout(home_form1Layout);
    home_form1Layout.setHorizontalGroup(
        home_form1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(home_form1Layout.createSequentialGroup()
            .addContainerGap(279, Short.MAX_VALUE)
            .addGroup(home_form1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, home_form1Layout.createSequentialGroup()
                    .addComponent(jButton1)
                    .addGap(54, 54, 54)
                    .addComponent(jButton2)
                    .addGap(318, 318, 318))
                .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, home_form1Layout.createSequentialGroup()
                    .addComponent(jLabel1)
                    .addGap(336, 336, 336))))
        .addGroup(home_form1Layout.createSequentialGroup()
            .addGap(347, 347, 347)
            .addComponent(jButton3)
            .addGap(0, 0, Short.MAX_VALUE))
    );
    home_form1Layout.setVerticalGroup(
        home_form1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, home_form1Layout.createSequentialGroup()
            .addGap(52, 52, 52)
            .addComponent(jLabel1)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 167, Short.MAX_VALUE)
            .addComponent(jButton3)
            .addGap(79, 79, 79)
            .addGroup(home_form1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(jButton2)
                .addComponent(jButton1))
            .addGap(157, 157, 157))
    );

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addComponent(home_form1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(0, 0, Short.MAX_VALUE))
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(home_form1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
    );

    pack();
}// </editor-fold>                        

/**
 * @param args the command line arguments
 */
public static void main(String args[]) {
    /* Set the Nimbus look and feel */
    //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
    /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
     * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
     */
    try {
        for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
            if ("Nimbus".equals(info.getName())) {
                javax.swing.UIManager.setLookAndFeel(info.getClassName());
                break;
            }
        }
    } catch (ClassNotFoundException ex) {
        java.util.logging.Logger.getLogger(Home.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(Home.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(Home.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(Home.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    }
    //</editor-fold>

    /* Create and display the form */
    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            new Home().setVisible(true);
        }
    });
}

// Variables declaration - do not modify                     
public javax.swing.JPanel home_form1;
private javax.swing.JButton jButton1;
private javax.swing.JButton jButton2;
private javax.swing.JButton jButton3;
private javax.swing.JLabel jLabel1;
private javax.swing.JRadioButtonMenuItem jRadioButtonMenuItem1;
private javax.swing.JLabel lblcontent;
private javax.swing.JLabel lblcontent1;
private javax.swing.JLabel lblcontent2;
public javax.swing.JLabel lblcontent3;
private javax.swing.JPanel panelMainContent;
private javax.swing.JPanel panelMainContent1;
private javax.swing.JPanel panelMainContent2;
private javax.swing.JPanel panelMainContent3;
// End of variables declaration                   
}