Add controls to a tab in JTabbedPane in Java

/*from  w ww. j  a v a  2 s. co m*/
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

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

public class Main{

  private JFrame frame = new JFrame();

  private JTabbedPane tabbedPane = new JTabbedPane();

  private JButton addTabButton = new JButton("Add Tab");

  private Dimension closeButtonSize;

  private int tabCounter = 0;

  public Main() {

    addTabButton.addActionListener(new ActionListener(){
      public void actionPerformed(ActionEvent e){
        add();
        
      }
      
    });

    frame.add(tabbedPane, BorderLayout.CENTER);
    frame.add(addTabButton, BorderLayout.SOUTH);

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    frame.pack();
    frame.setMinimumSize(new Dimension(300, 300));
    frame.setVisible(true);

  }

  public void add() {
    final JPanel content = new JPanel();
    JPanel tab = new JPanel(new FlowLayout());

    JLabel tabLabel = new JLabel("Tab " + (++tabCounter));

    JButton tabCloseButton = new JButton("X");
    tabCloseButton.setPreferredSize(closeButtonSize);
    tabCloseButton.addActionListener(new ActionListener() {

      public void actionPerformed(ActionEvent e) {
        int closeTabNumber = tabbedPane.indexOfComponent(content);
        tabbedPane.removeTabAt(closeTabNumber);
      }
    });

    tab.add(tabLabel);
    tab.add(tabCloseButton);

    tabbedPane.addTab(null, content);
    tabbedPane.setTabComponentAt(tabbedPane.getTabCount() - 1, tab);
  }

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

}