Java JPasswordField handle ENTER key pressed event

import java.awt.FlowLayout;
import java.util.Arrays;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JPasswordField;

class Demo extends JPanel {
  public Demo() {    
    setLayout(new FlowLayout());
    /*w w w  .j a v  a2s  .  c  o m*/
    JPasswordField passwordField = new JPasswordField(10);
    passwordField.setActionCommand("password");
    
    passwordField.addActionListener(e->{
      String cmd = e.getActionCommand();
      System.out.println(cmd);
      
      char[] input = passwordField.getPassword();
      System.out.println(Arrays.toString(input));
      
    });
    add(passwordField);
  }
}

public class Main {
  public static void main(String[] args) {
    Demo panel = new Demo();
    JFrame application = new JFrame();
    application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    application.add(panel);
    application.setSize(250, 250);
    application.setVisible(true);
  }
}

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPasswordField;

public class Main extends JFrame {
  JPasswordField passwordField; // password field with text

  public Main() {
    super("Testing");
    setLayout(new FlowLayout());
    // construct password field with default text
    passwordField = new JPasswordField("Hidden text");
    add(passwordField); // add passwordField to JFrame

    // register event handlers
    TextFieldHandler handler = new TextFieldHandler();

    passwordField.addActionListener(handler);
  } // end Main constructor

  // private inner class for event handling
  private class TextFieldHandler implements ActionListener {
    @Override//from  www .  j  a  v a 2 s.  c om
    public void actionPerformed(ActionEvent event) {
      String string = "";

      // user pressed Enter in JTextField passwordField
      if (event.getSource() == passwordField)
        string = String.format("passwordField: %s", event.getActionCommand());

      // display JTextField content
      JOptionPane.showMessageDialog(null, string);
    }
  } // end private inner class TextFieldHandler

  public static void main(String[] args) {
    Main Main = new Main();
    Main.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    Main.setSize(350, 100);
    Main.setVisible(true);
  }
}