JFrame visible - all else invisible.

[Paul Kelley]

I figure this is an easy one, but I don't see why my GUI only appears with a JFrame with the title "Java Message Server Information", and everything in the JFrame is transparent (i.e. not there). What I expected to see was 3 JLabels ("IP Address", "Port", "Topic Name"), and their corresponding JTextFields, and at the bottom of the JFrame a JButton labled "Accept" but instead I came up empty.
Can someone help me with this? Sorry if it's obvious, I'm very new to SWING.

Thanks!

Here's the code...

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
 
public class TopicGUI
{
    private TopicForm m_topicForm = null;
    private String m_ipAddr = null;
    private String m_port = null;
    private String m_topicName = null;
 
    public class TopicForm extends JPanel
    {
        public static final int IDX_TOTAL = 3; // There are 3 indexes all together.
        public static final int IDX_IPADDR = 0;
        public static final int IDX_PORT = 1;
        public static final int IDX_TOPICNAME = 2;
 
        private JTextField[] m_fields;
 
        /**
         * This is the constructor for the TopicGUI class. It is responsible for creating the
         * layout for the GUI to gather IP address, Port and Topic Name information from the
         * user.
         * @param labels String[] This is an array of String values indicating to the user
         * what is wanted (i.e. IP addres, Port or TopicName).
         * @param mnemonics char[] This is an array of single-letter ASCII values that indicate
         * to what field the GUI's cursor should jump when the hot-key is pressed.
         * @param widths int[] The MAXIMUM number of characters allowed as input for the
         * particular text field in focus.
         * @param tips String[] An array of full-length descriptions that assist the user in
         * understanding how to enter information into the text field.
         */
        public TopicForm(String[] labels, char[] mnemonics, int[] widths, String[] tips)
        {
            super(new BorderLayout());
            JPanel labelPanel = new JPanel(new GridLayout(labels.length, 1));
            JPanel fieldPanel = new JPanel(new GridLayout(labels.length, 1));
            add(labelPanel, BorderLayout.WEST);
            add(fieldPanel, BorderLayout.CENTER);
            m_fields = new JTextField[labels.length];
 
            // Create each text field for information gathering.
            for(int i=0; i < labels.length; i++)
            {
                m_fields[i] = new JTextField();
                if (i < tips.length)
                {
                    m_fields[i].setToolTipText(tips[i]);
                }
                if (i < widths.length)
                {
                    m_fields[i].setColumns(widths[i]);
                }
 
                JLabel lab = new JLabel(labels[i], JLabel.RIGHT);
                lab.setLabelFor(m_fields[i]);
                if (i < mnemonics.length)
                {
                    lab.setDisplayedMnemonic(mnemonics[i]);
                }
 
                labelPanel.add(lab);
                JPanel p = new JPanel(new FlowLayout(FlowLayout.LEFT));
                p.add(m_fields[i]);
                fieldPanel.add(p);
            } // End FOR i loop.
        }
 
        public String getText(int idx)
        {
            return(m_fields[idx].getText());
        }
    }
 
    public TopicGUI()
    {
        String[] labels = {"IP Address", "Port", "Topic Name"};
        char[] mnemonics = {'I', 'P', 'T'};
        int[] widths = {15, 5, 35};
        String[] descs = {"IP Address of box", "Port", "JMS Topic Name (case-sensitive)"};
 
        m_topicForm = new TopicForm(labels, mnemonics, widths, descs);
        JButton submit = new JButton("Accept");
 
        submit.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                m_ipAddr = m_topicForm.getText(0);
                m_port = m_topicForm.getText(1);
                m_topicName = m_topicForm.getText(2);
            }
        });
 
        JFrame frame = new JFrame("Java Message Server Information");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(m_topicForm, BorderLayout.NORTH);
        JPanel panel = new JPanel();
        panel.add(submit);
        frame.getContentPane().add(panel, BorderLayout.SOUTH);
        frame.pack();
        frame.setVisible(true);
    }
 
    public String[] getTopicInfo()
    {
        String[] topicInfo = new String[TopicForm.IDX_TOTAL];
        topicInfo[0] = m_ipAddr;
        topicInfo[1] = m_port;
        topicInfo[2] = m_topicName;
        return topicInfo;
    }
}
  

[Gregg Bolinger]

JFrame frame = new JFrame("Java Message Server Information");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(m_topicForm, BorderLayout.NORTH);
JPanel panel = new JPanel();
panel.add(submit);
frame.getContentPane().add(panel, BorderLayout.SOUTH);
frame.pack();
frame.setVisible(true);

You add panel, which is an empty JPanel to the frame. I don't see where you've added TopicForm to the frame.

[Paul Kelley]

Instantiated TopicForm near top of constructor signature "public TopicGUI()" like this...

        ...
        ...
        m_topicForm = new TopicForm(labels, mnemonics, widths, descs);
        ...
        ...

Then I add "TopicForm" to the JFrame in the following statement...

        ...
        frame.getContentPane().add(m_topicForm, BorderLayout.NORTH);
        ...

I would also presume JPanel to not be empty because of the statment...

        ...
        JPanel panel = new JPanel();
        panel.add(submit);
        ...

Where the variable "submit" was declared previously as...

        ...
        JButton submit = new JButton("Accept");
        ...

Thoughts?

[Ernest Friedman-Hill]

I don't see anything wrong with it. If I add the following:

public static void main(String[] argv) {
        new TopicGUI();
}

and then run the whole thing as "java TopicGUI", it seems to work perfectly.