Non me lo disegna D:
Ecco le due classi come sono ora:
codice:
import java.awt.BorderLayout;
import java.awt.Color;
//import java.awt.event.MouseAdapter;
//import java.awt.event.MouseEvent;
//import java.awt.Label;

import javax.swing.JFrame;
import javax.swing.JTabbedPane;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JButton;
import javax.swing.SwingConstants;
//import javax.swing.border.EmptyBorder;
//import javax.swing.JTextField;
//import javax.swing.JPasswordField;

public class TabbedPane extends JFrame {
    
    private static final long serialVersionUID = 1L;
    //private JTextField txtUsername;
    //private JPasswordField passwordField;
    //private String username;
    //private JLabel exceptionLabel;
    
    public static void main( String args[] )
       { 
        TabbedPane tabbedPaneFrame = new TabbedPane();  
          tabbedPaneFrame.setVisible( true ); // display frame
       } // end main 
    
    
   // set up GUI
   public TabbedPane()
   {
       super( "JTabbedPane" );

       JTabbedPane tabbedPane = new JTabbedPane(); // create JTabbedPane 
       setTitle("Index Frame");
       setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       setBounds(100, 100, 450, 300);
       
       LoginPanel panel1 = new LoginPanel();
               tabbedPane.addTab( "Login", null, panel1, "Login Panel" ); 
      
      // set up panel2 and add it to JTabbedPane
      JLabel label2 = new JLabel( "panel two", SwingConstants.CENTER );
      JPanel panel2 = new JPanel(); // create second panel
      panel2.setBackground( Color.YELLOW ); // set background to yellow
      panel2.add( label2 ); // add label to panel
      tabbedPane.addTab( "Tab Two", null, panel2, "Second Panel" ); 


      getContentPane().add( tabbedPane ); // add JTabbedPane to frame
   } // end JTabbedPaneFrame constructor
} // end class JTabbedPaneFrame
E la seconda:

codice:
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.Label;

import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JButton;
import javax.swing.SwingConstants;
import javax.swing.border.EmptyBorder;
import javax.swing.JTextField;
import javax.swing.JPasswordField;

public class LoginPanel extends JPanel {
    private static final long serialVersionUID = 1L;
    private JPanel panel1;
    private JTextField txtUsername;
    private JPasswordField passwordField;
    private String username;
    private JLabel exceptionLabel;
    
    /**
     * Create the panel.
     */
    public LoginPanel() {
        // set up pane11 and add it to JTabbedPane 
        JLabel label1 = new JLabel( "Login", SwingConstants.CENTER );

        panel1 = new JPanel();
        panel1.setBorder(new EmptyBorder(5, 5, 5, 5));
        panel1.setLayout(null);
 
        txtUsername = new JTextField();
        txtUsername.setBounds(177, 60, 89, 20);
        panel1.add(txtUsername);
        txtUsername.setColumns(10);
 
        Label label = new Label("Username");
        label.setBounds(177, 32, 62, 22);
        panel1.add(label);
 
        Label label_1 = new Label("Password");
        label_1.setBounds(177, 93, 62, 22);
        panel1.add(label_1);
 
        passwordField = new JPasswordField();
        passwordField.setBounds(177, 121, 89, 20);
        panel1.add(passwordField);
 
        JButton btnLogin = new JButton("Sign In");
 
        btnLogin.setBounds(177, 162, 89, 23);
        panel1.add(btnLogin);
 
        exceptionLabel = new JLabel("");
        exceptionLabel.setBounds(175, 183, 181, 14);
        panel1.add(exceptionLabel);
        panel1.add( label1 ); // add label to panel
     }
}