JTable with dynamic JPopupMenu

I am trying to code a context menu that changes its items depending on the row. The problem is that I cannot get it to update. Here is a working example:

package jframe.jTable;

import java.awt.BorderLayout;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Arrays;
import java.util.Vector;

import javax.swing.JFrame;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;
import javax.swing.JPopupMenu;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.SwingUtilities;
import javax.swing.event.PopupMenuEvent;
import javax.swing.event.PopupMenuListener;

public class TestTableRightClick {
    JPopupMenu popupMenu;

    protected void initUI() {
        final JFrame frame = new JFrame(TestTableRightClick.class.getSimpleName());
        Vector<String> columns = new Vector<String>(Arrays.asList("Name", "Age"));
        Vector<Vector<String>> data = new Vector<Vector<String>>();
        for (int i = 0; i < 50; i++) {
            Vector<String> row = new Vector<String>();
            for (int j = 0; j < columns.size(); j++) {
                row.add("Cell " + (i + 1) + "," + (j + 1));
            }
            data.add(row);
        }
        JTable table = new JTable(data, columns);
        popupMenu = new JPopupMenu();

        popupMenu.addPopupMenuListener(new PopupMenuListener() {

            @Override
            public void popupMenuWillBecomeVisible(PopupMenuEvent e) {
                //int rowAtPoint = table.rowAtPoint(SwingUtilities.convertPoint(popupMenu, new Point(0, 0), table));
                //generateTablePopupMenu(rowAtPoint);

                SwingUtilities.invokeLater(new Runnable() {
                    @Override
                    public void run() {
                        int rowAtPoint = table.rowAtPoint(SwingUtilities.convertPoint(popupMenu, new Point(0, 0), table));
                        generateTablePopupMenu(rowAtPoint);
                        if (rowAtPoint > -1) {
                            table.setRowSelectionInterval(rowAtPoint, rowAtPoint);
                        }
                    }
                });
            }

            private void generateTablePopupMenu(int rowAtPoint) {
                System.out.println(rowAtPoint);
                popupMenu.removeAll();
                if ( (rowAtPoint & 1) == 0 ) {
                 System.out.println("even");
                 JMenuItem item = new JMenuItem("Even Row");
                 popupMenu.add(item);}
                 else {
                     System.out.println("odd");
                     //popupMenu = new JPopupMenu();
                     JMenuItem item = new JMenuItem("Odd Row");
                     popupMenu.add(item);}

            }

            @Override
            public void popupMenuWillBecomeInvisible(PopupMenuEvent e) {
                // TODO Auto-generated method stub

            }

            @Override
            public void popupMenuCanceled(PopupMenuEvent e) {
                // TODO Auto-generated method stub

            }


        });


        table.setComponentPopupMenu(popupMenu);
        frame.add(new JScrollPane(table), BorderLayout.CENTER);
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                new TestTableRightClick().initUI();
            }
        });
    }
}

When the code is executed, the JPopupMenu is and stays blank, even though the correct row is being reported back to generateTablePopupMenu, and a new JMenuItem is added. I've also tried to make the code run before .invokelater like this:

public void popupMenuWillBecomeVisible(PopupMenuEvent e) {
                int rowAtPoint = table.rowAtPoint(SwingUtilities.convertPoint(popupMenu, new Point(0, 0), table));
                generateTablePopupMenu(rowAtPoint);

                SwingUtilities.invokeLater(new Runnable() {...

But then the row integer given back is always -1. How can I get this to work? And WHY does this work, why did my code not work? I've searched the net for an answer to my problem but did not find much, strangely.

Whenever you add/remove components from a visible container you need to tell the container that you are finished adding components so the layout manager can be invoked.

Your logic should be:

private void generateTablePopupMenu(int rowAtPoint)
{
    popupMenu.removeAll();

    if ( (rowAtPoint & 1) == 0 )
    {
        JMenuItem item = new JMenuItem("Even Row");
        popupMenu.add(item);}
    else
    {
        JMenuItem item = new JMenuItem("Odd Row");
        popupMenu.add(item);
    }

    popupMenu.revalidate();
}