Different value of components from JPanel when coming through different event types

Question

There is one panel which contains 4 components; 1 JLabel, 1 JButton, 1 JTextField and 1 JPopupMenu
There is a method "testMethod()" in which first I get the number of components from the panel and then the type of component(JButton, JLabel etc).

Now there are 2 scenarios occurring when the control flow goes to testMethod():

1. When coming through JButton click event, it shows 4 components on panel and after get all 4 components
2. When coming through JMenuItem click event, it shows 3 components on panel(not getting JPopupMenu) and after only 3 components(not getting JPopupMenu)

I don't get it what is causing this behavior. I searched a lot on the internet and also read JPopupMenu documents but found nothing about this.

Following is the code:
(it is a part of very big code so I put here only that code which is showing the scenario)

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.EventQueue;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JPopupMenu;
import javax.swing.JLabel;
import javax.swing.JMenuItem;
import javax.swing.JButton;
import javax.swing.JTextField;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class TestProject extends JFrame {

    JPanel panel;
    private JPanel contentPane;
    private JTextField textField;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    TestProject frame = new TestProject();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public TestProject() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 450, 300);
        contentPane = new JPanel();
        contentPane.setLayout(new BorderLayout(0, 0));
        setContentPane(contentPane);

        panel = new JPanel();
        contentPane.add(panel, BorderLayout.CENTER);

        JLabel lblNewLabel = new JLabel("New label");
        panel.add(lblNewLabel);

        JButton btnNewButton = new JButton("New button");
        btnNewButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                testMethod();
            }
        });
        panel.add(btnNewButton);

        textField = new JTextField();
        panel.add(textField);
        textField.setColumns(10);

        // Creating upper level container
        JPopupMenu editMenu = new JPopupMenu("Edit");

        JMenuItem item1 = new JMenuItem("Item 1");
        item1.setBackground(Color.WHITE);

        JMenuItem item2 = new JMenuItem("Item 2");
        item2.setBackground(Color.WHITE);
        item2.setBackground(Color.WHITE);
        // Setting Copy action listener
        item2.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                testMethod();
            }
        });

        // Adding the menu items on the popup menu
        editMenu.add(item1);
        editMenu.add(item2);

        panel.addMouseListener(new MouseAdapter() {
               public void mouseClicked(MouseEvent e) {
                   // Added check to open menu only on left click
                   if (e.getButton() == MouseEvent.BUTTON3)
                       editMenu.show(panel, e.getX(), e.getY());
               }               
            });

        // Adding popup menu to the logAreaPanel
        panel.add(editMenu); 

    }

    void testMethod()
    {
        // Here getting number of components of panel
        // When coming through JButton click event, it shows 4 components on panel and after get all 4 components 
        int items = panel.getComponentCount();
        Component c;

        // Getting all the trees one by one and storing their data into StringBuilder
        for(int loopCounter = 0; loopCounter < items; loopCounter++)
        {
            // here getting different component types
            // When coming through JMenuItem click event, it shows 3 components on panel(not getting JPopupMenu) and after only 3 components(not getting JPopupMenu)
            c = panel.getComponent(loopCounter);
        }
    }
}

Any help would be appreciated. :-)

Answer 1

You don't need to add the popup to the component. The preferred way is to just use

panel.setComponentPopupMenu(editMenu);

As per the tutorial, You could use a MouseListener.

//panel.add(editMenu); 
panel.addMouseListener(new MouseAdapter(){
    public void mousePressed(MouseEvent e) {
        maybeShowPopup(e);
    }

    public void mouseReleased(MouseEvent e) {
        maybeShowPopup(e);
    }

    private void maybeShowPopup(MouseEvent e) {
        if (e.isPopupTrigger()) {
            editMenu.show(e.getComponent(), e.getX(), e.getY());
        }
    }
});

That way the component count will always be three, because it is never added to the panel.