title: Authenticator getPasswordAuthentication not called
body: <p>I am new to Network Programming.
  Here is my Code:</p>
  
  <pre><code>public class ComputerNetworks extends Authenticator {
      private JDialog passwordDialog;
      private JLabel mainLabel= new JLabel("Please enter username and password: ");
      private JLabel userLabel = new JLabel("Username: ");
      private JLabel passwordLabel = new JLabel("Password: ");
      private JTextField usernameField = new JTextField(20);
      private JPasswordField passwordField = new JPasswordField(20);
      private JButton okButton = new JButton("OK");
      private JButton cancelButton = new JButton("Cancel");
  
      public ComputerNetworks( ) {
          this("", new JFrame());
      }
  
      public ComputerNetworks(String username) {
          this(username, new JFrame());
      }
  
      public ComputerNetworks(JFrame parent) {
          this("", parent);
      }
  
      public ComputerNetworks(String username, JFrame parent) {
          this.passwordDialog = new JDialog(parent, true);
          Container pane = passwordDialog.getContentPane( );
          pane.setLayout(new GridLayout(4, 1));
          pane.add(mainLabel);
          JPanel p2 = new JPanel( );
          p2.add(userLabel);
          p2.add(usernameField);
          usernameField.setText(username);
          pane.add(p2);
          JPanel p3 = new JPanel( );
          p3.add(passwordLabel);
          p3.add(passwordField);
          pane.add(p3);
          JPanel p4 = new JPanel( );
          p4.add(okButton);
          p4.add(cancelButton);
          pane.add(p4);
          ActionListener al = new OKResponse( );
          okButton.addActionListener(al);
          usernameField.addActionListener(al);
          passwordField.addActionListener(al);
          cancelButton.addActionListener(new CancelResponse( ));
          passwordDialog.pack( );
          passwordDialog.setVisible(true);
  
      }
  
      private void show( ) {
          String prompt = this.getRequestingPrompt( );
          if (prompt == null) {
              String site = this.getRequestingSite().getHostName( );
              String protocol = this.getRequestingProtocol( );
              int port = this.getRequestingPort();
              if (site != null &amp; protocol != null) {
                  prompt = protocol + "://" + site;
                  if (port &gt; 0) 
                      prompt += ":" + port;
              } else {
                  prompt = "";
              }
          }
          mainLabel.setText("Please enter username and password for "
              + prompt + ": ");
          passwordDialog.pack();
          passwordDialog.setVisible(true);
      }
  
  
      PasswordAuthentication response = null;
  
      class OKResponse implements ActionListener {
  
          @Override
          public void actionPerformed(ActionEvent e) {
              System.out.println("OK clicked");
              passwordDialog.setVisible(false);
              // The password is returned as an array of
              // chars for security reasons.
              char[] password = passwordField.getPassword( );
              String username = usernameField.getText( );
              // Erase the password in case this is used again.
              passwordField.setText("");
              response = new PasswordAuthentication(username, password);
          }
      }
  
      class CancelResponse implements ActionListener {
          public void actionPerformed(ActionEvent e) {
              passwordDialog.hide( );
              // Erase the password in case this is used again.
              passwordField.setText("");
              response = null;
          }
      }
  
      public PasswordAuthentication getPasswordAuthentication( ) {
          this.show();
          return this.response;
      }
  
      public static void main(String[] args) throws Exception {
          Authenticator.setDefault(new ComputerNetworks());
          URL u = new URL("http://www.google.co.in");
          InputStream in = u.openStream();
      }
  }
  </code></pre>
  
  <p>I am running this code from IDE. The problem is <code>getPasswordAuthentication()</code> method of <code>Authenticator</code> is not getting called though I have opened a stream with a URL.
  Please help.
  Thanks in advance</p>