Salve a tutti,
scusate il ritardo ma ho avuto dei problemi. Riporto il codice creato.
codice:
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;


public class Calc extends JFrame{


    JButton[] pulsanti = new JButton[9];
    
    public Calc() {
        initComponents();
		GridLayout grid = new GridLayout(3, 3);
		setLayout(grid);
        
		for(int k = 0; k < pulsanti.length; k++) {
            pulsanti[k] = new JButton();
            add(pulsanti[k]);
		}
    } 
    
    
    
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {


        jMenuBar1 = new javax.swing.JMenuBar();
        jMenu1 = new javax.swing.JMenu();
        jMenuNew = new javax.swing.JMenuItem();
        jSeparator1 = new javax.swing.JPopupMenu.Separator();
        jMenuStatistics = new javax.swing.JMenuItem();
        jMenuSettings = new javax.swing.JMenuItem();
        jMenuSave = new javax.swing.JMenuItem();
        jSeparator2 = new javax.swing.JPopupMenu.Separator();
        jMenuEsc = new javax.swing.JMenuItem();
        jMenu2 = new javax.swing.JMenu();
        jMenuGuide = new javax.swing.JMenuItem();


        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("Calcolatrice");
        setMinimumSize(new java.awt.Dimension(400, 320));


        jMenu1.setText("File");


        jMenuNew.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_F2, 0));
        jMenuNew.setText("A");
        jMenu1.add(jMenuNew);
        jMenu1.add(jSeparator1);


        jMenuStatistics.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_F4, 0));
        jMenuStatistics.setText("B");
        jMenu1.add(jMenuStatistics);


        jMenuSettings.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_F5, 0));
        jMenuSettings.setText("Impostazioni");
        jMenu1.add(jMenuSettings);


        jMenuSave.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_S, java.awt.event.InputEvent.CTRL_MASK));
        jMenuSave.setText("D");
        jMenu1.add(jMenuSave);
        jMenu1.add(jSeparator2);


        jMenuEsc.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_ESCAPE, 0));
        jMenuEsc.setText("Esci");
        jMenu1.add(jMenuEsc);


        jMenuBar1.add(jMenu1);


        jMenu2.setText("Aiuto");


        jMenuGuide.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_F1, 0));
        jMenuGuide.setText("H");
        jMenu2.add(jMenuGuide);


        jMenuBar1.add(jMenu2);


        setJMenuBar(jMenuBar1);


        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 410, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 279, Short.MAX_VALUE)
        );


        pack();
        setLocationRelativeTo(null);
    }// </editor-fold>                        
    // Variables declaration - do not modify                     
    private javax.swing.JMenu jMenu1;
    private javax.swing.JMenu jMenu2;
    private javax.swing.JMenuBar jMenuBar1;
    private javax.swing.JMenuItem jMenuEsc;
    private javax.swing.JMenuItem jMenuGuide;
    private javax.swing.JMenuItem jMenuNew;
    private javax.swing.JMenuItem jMenuSave;
    private javax.swing.JMenuItem jMenuSettings;
    private javax.swing.JMenuItem jMenuStatistics;
    private javax.swing.JPopupMenu.Separator jSeparator1;
    private javax.swing.JPopupMenu.Separator jSeparator2;
    // End of variables declaration                   
}

Grazie