Java - Error en main

import javax.swing.*;

import java.awt.*;

import java.awt.event.*;

import javax.swing.JFrame;

import java.awt.BorderLayout;

import java.awt.Color;

import java.awt.FlowLayout;

import java.awt.Font;

import java.awt.GridLayout;

import java.awt.Insets;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import javax.swing.BorderFactory;

import javax.swing.JButton;

import javax.swing.JFrame;

import javax.swing.JLabel;

import javax.swing.JOptionPane;

import javax.swing.JPanel;

import javax.swing.JTextArea;

import javax.swing.JTextField;

import java.awt.Dimension;

public class Formulario extends JFrame implements ActionListener{

	private JMenu menu1;

	private JMenuBar mb;

	private JMenuItem telefono,nombre,apellido;

public Formulario () {

mb=new JMenuBar();

setJMenuBar(mb);

menu1=new JMenu("Buscar");

mb.add(menu1);

telefono=new JMenuItem("telefono");

menu1.add(telefono);

telefono.addActionListener(this);

nombre=new JMenuItem("nombre");

menu1.add(nombre);

nombre=new JMenuItem("apellido");

menu1.add(apellido); //LINEA 40

}

    public void actionPerformed(ActionEvent e) {

    	Container f=this.getContentPane();

        if (e.getSource()==telefono) {

        System.out.printf ("Su nombre de usuario es: ");

    }

    }

public static void main(String[] ar) {

        Formulario formulario1=new Formulario();

	formulario1.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );

        formulario1.setBounds(10,20,300,200);

        formulario1.setVisible(true);

    }

}

C:\F>java Formulario

Exception in thread "main" java.lang.NullPointerException

        at java.awt.Container.addImpl(Unknown Source)

        at java.awt.Container.add(Unknown Source)

        at javax.swing.JPopupMenu.add(Unknown Source)

        at javax.swing.JMenu.add(Unknown Source)

        at Formulario.<init>(Formulario.java:40)

        at Formulario.main(Formulario.java:53)

nombre=new JMenuItem("apellido");

apellido = new JMenuItem("apellido");