Java Swing - 如何将动作命令设置为JButton

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

import javax.swing.JButton;
import javax.swing.JOptionPane;

public class Main {
  public static void main(final String args[]) {
    JButton button = new JButton("Text Button");
    ActionListener actionListener = new ActionListener() {
      public void actionPerformed(ActionEvent actionEvent) {
        String command = actionEvent.getActionCommand();
        System.out.println("Selected: " + command);
      }
    };

    button.setActionCommand("First");
    button.addActionListener(actionListener);

    JOptionPane.showMessageDialog(null, button);
  }
}