Java Swing - 如何handle JTabbedPane的Tab切换事件

import java.awt.BorderLayout;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTabbedPane;

public class Main extends JFrame {

  private void init() {
    this.setLayout(new BorderLayout());
    JPanel topPanel = new JPanel();
    final JLabel topLabel = new JLabel("North");
    topPanel.add(topLabel);
    this.add(topPanel, BorderLayout.NORTH);

    JTabbedPane tabbedPane = new JTabbedPane();
    JPanel firstTabCont = new JPanel();
    firstTabCont.add(new JLabel("First"));
    tabbedPane.addTab("First", firstTabCont);

    JPanel secondTabCont = new JPanel();
    secondTabCont.add(new JLabel("Second"));
    tabbedPane.addTab("Second", secondTabCont);

    this.add(tabbedPane, BorderLayout.CENTER);

    JPanel bottomPanel = new JPanel();
    final JLabel bottomLabel = new JLabel("South");
    bottomPanel.add(bottomLabel);
    this.add(bottomPanel, BorderLayout.SOUTH);

    tabbedPane.addChangeListener(evt -> {
      JTabbedPane pane = (JTabbedPane) evt.getSource();
      int selectedIndex = pane.getSelectedIndex();
      if (selectedIndex == 0) {
        topLabel.setText("");
        topLabel.setText("Hi");

        bottomLabel.setText("");
        bottomLabel.setText("Bye");
      } else {
        topLabel.setText("");
        topLabel.setText("Bye");

        bottomLabel.setText("");
        bottomLabel.setText("Hi");
      }

    });
    this.pack();
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    this.setVisible(true);
  }

  public static void main(String[] args) {
    new Main().init();
  }
}