Netbeans - JFrame paintcomponent问题

Question

我正在尝试在NetBeans生成的JFrame上显示super.paintComponent。但是，paintcomponent就不会在那里工作。我希望paintComponent显示的JFrame称为“GameFrame”。 BTW这个绘画类是在我自己编写的JFrame上工作的。 我也是java的新手。

这是我的代码：

/*
 * 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 MainCode;


public class DisplayFrame extends javax.swing.JFrame {

    /**
     * Creates new form DisplayFrame
     */
    public DisplayFrame() {
        initComponents();
        GameFrame.setVisible(true);
    }    /**
     * 
     * 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")
    _2D_Shapes_ Draw = new _2D_Shapes_();
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        GameFrame = new javax.swing.JFrame();
        PlayButton = new javax.swing.JButton();

        GameFrame.setExtendedState(MAXIMIZED_BOTH);
        GameFrame.setUndecorated(true);

        javax.swing.GroupLayout GameFrameLayout = new javax.swing.GroupLayout(GameFrame.getContentPane());
        GameFrame.getContentPane().setLayout(GameFrameLayout);
        GameFrameLayout.setHorizontalGroup(
            GameFrameLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 1086, Short.MAX_VALUE)
        );
        GameFrameLayout.setVerticalGroup(
            GameFrameLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 703, Short.MAX_VALUE)
        );

        GameFrame.setVisible(true);

        setExtendedState(MAXIMIZED_BOTH);

        PlayButton.setFont(new java.awt.Font("Al-seana", 0, 36)); // NOI18N
        PlayButton.setText("PLAY!");
        PlayButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                PlayButtonActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addComponent(PlayButton, javax.swing.GroupLayout.DEFAULT_SIZE, 467, Short.MAX_VALUE)
                .addGap(0, 0, 0))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap(216, Short.MAX_VALUE)
                .addComponent(PlayButton, javax.swing.GroupLayout.PREFERRED_SIZE, 78, javax.swing.GroupLayout.PREFERRED_SIZE))
        );

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

    private void PlayButtonActionPerformed(java.awt.event.ActionEvent evt) {                                           
        GameFrame.setVisible(true);

        GameFrame.add(Draw);
    }                                          

    /**
     * @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 ("Windows".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(DisplayFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(DisplayFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(DisplayFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(DisplayFrame.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 DisplayFrame().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify                     
    private javax.swing.JFrame GameFrame;
    private javax.swing.JButton PlayButton;
    // End of variables declaration                   
}

注意：如果你看不到它，[GameFrame.add（Draw）;]命令就在中间。