Java Component not showing on startup

Question

I have a Class that adds an ImageIcon in the East of a TextField if you pass it to that Class, it's working pretty good during runtime if I press a Button to change frames, but the Image is not showing up at the startup.

import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.border.EmptyBorder;
import javax.swing.JButton;

import java.awt.Cursor;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;

import javax.swing.ImageIcon;
import javax.swing.JLabel;

public class TestStartFrame extends JFrame
{

/**
 * 
 */
private static final long serialVersionUID = 1L;
private JPanel contentPane;

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

/**
 * Create the frame.
 */
public TestStartFrame()
{
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 450, 300);
    contentPane = new JPanel();
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    contentPane.setLayout(new BorderLayout(0, 0));
    setContentPane(contentPane);

    JButton btnNewButton = new JButton("New button");
    contentPane.add(btnNewButton, BorderLayout.CENTER);
    btnNewButton.addActionListener(new ActionListener()
    {

        @Override
        public void actionPerformed(ActionEvent e)
        {
            SecondFrame fr = new SecondFrame();
            fr.setVisible(true);
            try
            {
                int r = 250;
                int g = 250;
                int b = 250;
                UIManager.put("control", new Color(r, g, b));
                UIManager
                        .setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
                UIManager.put("control", new Color(r, g, b));
                SwingUtilities
                        .updateComponentTreeUI(SecondFrame.contentPane);
            } catch (Exception e1)
            {
                System.out.println(e1.getMessage());
            }
            dispose();
        }
    });

}

}

class SecondFrame extends JFrame
{
/**
 * 
 */
private static final long serialVersionUID = 1L;
public final static JPanel contentPane = new JPanel();

/**
 * Create the frame.
 */
public SecondFrame()
{
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 450, 300);
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    setContentPane(contentPane);
    contentPane.setLayout(new BorderLayout());
    JTextField txt = new JTextField();
    contentPane.add(txt, BorderLayout.CENTER);
    txt = ClearImage.addImage(txt);

}
}

class ClearImage
{

public static JTextField addImage(final JTextField comp)
{

    Image image = new BufferedImage(10, 25, BufferedImage.TYPE_INT_RGB);
    Graphics graphics = image.getGraphics();
    graphics.setColor(Color.WHITE);
    graphics.fillRect(0, 0, 10, 25);
    graphics.setColor(Color.LIGHT_GRAY);
    graphics.fillOval(0, 7, 10, 10);
    graphics.setColor(Color.GRAY);
    graphics.drawLine(2, 9, 8, 15);
    graphics.drawLine(2, 15, 8, 9);

    JLabel lblClear = new JLabel(new ImageIcon(image));
    comp.setLayout(new BorderLayout());
    comp.add(lblClear, BorderLayout.EAST);

    lblClear.setCursor(new Cursor(Cursor.DEFAULT_CURSOR));
    lblClear.addMouseListener(new MouseAdapter()
    {
        @Override
        public void mouseClicked(MouseEvent e)
        {
            comp.setText("");
        }
    });

    return comp;

}

public static JTextField removeImage(final JTextField comp)
{
    comp.removeAll();
    return comp;
}

}

If I place the UI change before the Frame visible, I don't have that problem, could anyone explain me why is it that way?

Answer 1

Your problem is caused by the change of UI factory on the JTextField (this is triggered by the installation of the Nimbus L&F and the updateComponentTreeUI()).

When you do that the second call, you automatically uninstall the previous L&F and UI factory of the JTextField. By default, this is Metal L&F Text UI (MetalTextFieldUI) which extends BasicTextUI. This invokes the method javax.swing.plaf.basic.BasicTextUI.uninstallUI(JComponent) and its content is the following:

public void uninstallUI(JComponent c) {
        // detach from the model
        editor.removePropertyChangeListener(updateHandler);
        editor.getDocument().removeDocumentListener(updateHandler);

        // view part
        painted = false;
        uninstallDefaults();
        rootView.setView(null);
        c.removeAll();
        LayoutManager lm = c.getLayout();
        if (lm instanceof UIResource) {
            c.setLayout(null);
        }

        // controller part
        uninstallKeyboardActions();
        uninstallListeners();

        editor = null;
    }

Notice the call c.removeAll() which basically removes your label from the hierarchy and hence causes the issue you are seeing.

1. Arguably, we could say that adding components to primitive Swing widgets is not ideal and this is not how they were intended to be used. I personally find that argument quite weak, but I know that many Swing lovers are found of it.

2. Simply make sure to do the update of the UI before adding your JLabel or extends JTextField and upon update of the UI, re-install your JLabel in the JTextField.

Small example (just to demo my explanation):

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;

import javax.swing.ImageIcon;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.EmptyBorder;

public class TestAddImageToTextField {

    private static class MyJTextField extends JTextField {
        @Override
        public void updateUI() {
            removeAll();
            super.updateUI();
            Image image = buildImage();

            JLabel lblClear = new JLabel(new ImageIcon(image));
            lblClear.addMouseListener(new MouseAdapter() {
                @Override
                public void mouseClicked(MouseEvent e) {
                    MyJTextField.this.setText("");
                }
            });
            setLayout(new BorderLayout());
            add(lblClear, BorderLayout.EAST);
        }

        private Image buildImage() {
            Image image = new BufferedImage(10, 25, BufferedImage.TYPE_INT_RGB);
            Graphics graphics = image.getGraphics();
            graphics.setColor(Color.WHITE);
            graphics.fillRect(0, 0, 10, 25);
            graphics.setColor(Color.LIGHT_GRAY);
            graphics.fillOval(0, 7, 10, 10);
            graphics.setColor(Color.GRAY);
            graphics.drawLine(2, 9, 8, 15);
            graphics.drawLine(2, 15, 8, 9);
            return image;
        }
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    TestAddImageToTextField frame = new TestAddImageToTextField();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    private JComponent contentPane;

    /**
     * Create the frame.
     * 
     * @throws UnsupportedLookAndFeelException
     * @throws IllegalAccessException
     * @throws InstantiationException
     * @throws ClassNotFoundException
     */
    public TestAddImageToTextField() throws ClassNotFoundException, InstantiationException, IllegalAccessException,
            UnsupportedLookAndFeelException {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setBounds(100, 100, 450, 300);
        contentPane = (JComponent) frame.getContentPane();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        contentPane.setLayout(new BorderLayout(0, 0));
        MyJTextField comp = new MyJTextField();

        contentPane.add(comp);
        frame.setVisible(true);
        installNimbusLAF();

    }

    private void installNimbusLAF() throws ClassNotFoundException, InstantiationException, IllegalAccessException,
            UnsupportedLookAndFeelException {
        int r = 250;
        int g = 250;
        int b = 250;
        UIManager.put("control", new Color(r, g, b));
        UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
        UIManager.put("control", new Color(r, g, b));
        SwingUtilities.updateComponentTreeUI(contentPane);
    }

}