Рисование внутри определенных c jFrame и jPanel

Question

Мне нужно рисовать круги с помощью graphics2D, я уже знаю, кому их рисовать, но они мне нужны внутри c JPanel. Я пробовал много способов, но они не работали, и все кнопки и другие JPanel исчезают. Класс известен как VentanaPintado, а панель для рисования внутри называется TestingPanelGraphics. Я пробовал создавать классы jPlanel, но он не работает, не знаю, сделал ли я это неправильно, но там я пишу код. Кто-нибудь может мне помочь? Спасибо! :)

public class VentanaPintado extends javax.swing.JFrame {
public VentanaPintado() {
    initComponents();
    this.setVisible(true);
}

@SuppressWarnings("unchecked")                         
private void initComponents() {

    jLabel3 = new javax.swing.JLabel();
    jPanel1 = new javax.swing.JPanel();
    TestingPanelGraphics = new javax.swing.JPanel();
    Siguiente = new javax.swing.JButton();

    jLabel3.setFont(new java.awt.Font("Times New Roman", 0, 24)); // NOI18N
    jLabel3.setForeground(new java.awt.Color(255, 255, 255));
    jLabel3.setText("Seleccione:");

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

    jPanel1.setBackground(new java.awt.Color(68, 49, 141));

    TestingPanelGraphics.setMaximumSize(new java.awt.Dimension(500, 500));
    TestingPanelGraphics.setMinimumSize(new java.awt.Dimension(500, 500));
    TestingPanelGraphics.setPreferredSize(new java.awt.Dimension(500, 500));
    TestingPanelGraphics.setRequestFocusEnabled(false);

    javax.swing.GroupLayout TestingPanelGraphicsLayout = new javax.swing.GroupLayout(TestingPanelGraphics);
    TestingPanelGraphics.setLayout(TestingPanelGraphicsLayout);
    TestingPanelGraphicsLayout.setHorizontalGroup(
        TestingPanelGraphicsLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 500, Short.MAX_VALUE)
    );
    TestingPanelGraphicsLayout.setVerticalGroup(
        TestingPanelGraphicsLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 500, Short.MAX_VALUE)
    );

    Siguiente.setBackground(new java.awt.Color(217, 176, 255));
    Siguiente.setFont(new java.awt.Font("Tw Cen MT Condensed Extra Bold", 0, 24)); // NOI18N
    Siguiente.setText("Empezar");
    Siguiente.setToolTipText("");

    javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
    jPanel1.setLayout(jPanel1Layout);
    jPanel1Layout.setHorizontalGroup(
        jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(jPanel1Layout.createSequentialGroup()
            .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(jPanel1Layout.createSequentialGroup()
                    .addGap(221, 221, 221)
                    .addComponent(Siguiente, javax.swing.GroupLayout.PREFERRED_SIZE, 210, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGroup(jPanel1Layout.createSequentialGroup()
                    .addGap(86, 86, 86)
                    .addComponent(TestingPanelGraphics, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
            .addContainerGap(405, Short.MAX_VALUE))
    );
    jPanel1Layout.setVerticalGroup(
        jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
            .addContainerGap()
            .addComponent(TestingPanelGraphics, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(35, 35, 35)
            .addComponent(Siguiente, javax.swing.GroupLayout.PREFERRED_SIZE, 50, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addContainerGap(43, Short.MAX_VALUE))
    );

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(0, 0, Short.MAX_VALUE))
    );

    pack();
}                 

public static void main(String args[]) {
    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(VentanaPintado.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(VentanaPintado.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(VentanaPintado.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(VentanaPintado.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    }
    //</editor-fold>

    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            new VentanaPintado().setVisible(true);
        }
    });
}
              
private javax.swing.JButton Siguiente;
private javax.swing.JPanel TestingPanelGraphics;
private javax.swing.JLabel jLabel3;
private javax.swing.JPanel jPanel1;      
}