Duvida

package tuxdesign;


public class Principal extends javax.swing.JFrame {

    public Principal() {
        initComponents();
    }

    // <editor-fold defaultstate="collapsed" desc=" Código Gerado ">
    private void initComponents() {
        jPanel1 = new javax.swing.JPanel();
        jMenuBar1 = new javax.swing.JMenuBar();
        jArquivo = new javax.swing.JMenu();
        jMenuItem1 = new javax.swing.JMenuItem();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        jPanel1.setBorder(javax.swing.BorderFactory.createBevelBorder(javax.swing.border.BevelBorder.RAISED));
        org.jdesktop.layout.GroupLayout jPanel1Layout = new org.jdesktop.layout.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(0, 396, Short.MAX_VALUE)
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(0, 275, Short.MAX_VALUE)
        );

        jArquivo.setText("Menu");
        jMenuItem1.setLabel("Area Restrita");
        jMenuItem1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jMenuItem1ActionPerformed(evt);
            }
        });

        jArquivo.add(jMenuItem1);

        jMenuBar1.add(jArquivo);

        setJMenuBar(jMenuBar1);

        org.jdesktop.layout.GroupLayout layout = new org.jdesktop.layout.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(jPanel1, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(jPanel1, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );
        pack();
    }// </editor-fold>

    Adm a = new Adm();
    private void jMenuItem1ActionPerformed(java.awt.event.ActionEvent evt) {                                           
a.show();
    }                                          


    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new Principal().setVisible(true);
            }
        });
    }
    
    // Declaração de variáveis - não modifique
    private javax.swing.JMenu jArquivo;
    private javax.swing.JMenuBar jMenuBar1;
    private javax.swing.JMenuItem jMenuItem1;
    private javax.swing.JPanel jPanel1;
    // Fim da declaração de variáveis
    
}

Adm a = new Adm();
    private void jMenuItem1ActionPerformed(java.awt.event.ActionEvent evt) {                                           
a.show();
    }