Can't get text from another class to print out on another one (noob)

Question

I posted this code earlier, and I got alot of helpful answers and the majority was that I need to change my code completely. Which I understand, and I will do tomorrow! But right now, this is eating away at me at why this won't work.

I am trying to get the sendText from the ChatBox class, to my MessageWindow class and output in the messagePane. That's it. It seems so simple, and it probably is...but I have literally been at this for 10 hours straight. I just want it to output what I put in the ChatBox to the MessageWindow, without completely changing my code. Please help :(

public class ChatBox extends JPanel {

private JScrollPane scrollPane;
private String sendText;

public ChatBox() {
    final JTextArea chatPane = new JTextArea();

    scrollPane = new JScrollPane(chatPane,
            JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
            JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
    add(scrollPane);
    scrollPane.setMinimumSize(new Dimension(550, 50));
    scrollPane.setPreferredSize(new Dimension(550, 50));

    chatPane.addKeyListener(new KeyListener() {

        @Override
        public void keyPressed(KeyEvent e) {
        }

        @Override
        public void keyReleased(KeyEvent e) {
            if( e.getKeyCode() == KeyEvent.VK_ENTER ) {
                sendText = chatPane.getText();
                setText(sendText);
                chatPane.setText(null);
                // System.out.println(sendText); // I can see this in console
            }

        }

        @Override
        public void keyTyped(KeyEvent e) {
        }

    });

}


public String getText() {
    return sendText;
}


public void setText(String sendText) {
    this.sendText = sendText;
}

}

In my head, I am setting the sendText -> whatever I input. Then in the MessageWindow class, I am trying to use the getter to get the text and output in the messagePane.

public class MessageWindow extends JPanel {

private ChatBox box = new ChatBox();

public MessageWindow() {
    JTextArea messagePane = new JTextArea();

    setLayout(new GridBagLayout());

    GridBagConstraints gc = new GridBagConstraints();

    gc.weightx = 1;
    gc.weighty = 1;
    gc.fill = GridBagConstraints.BOTH;
    gc.insets = new Insets(5, 5, 5, 5);
    add(new JScrollPane(messagePane), gc);

    System.out.println(box.getText());   // Getting null in the console.
    messagePane.append(box.getText());   // Not getting anything on messagePane.

}

}

I know I need to use ActionListeners and a JTextField, instead of a JTextArea. And I promise I will start that tomorrow. I will scrap this whole program as it is, I just need to know why this basic things fails me :( I knew while I was learning Java that getters/setters were going to be a problem for me to completely understand, and I guess I am right about that lol...

Thanks for any help!!!

NEW CODE

public class MessageWindow extends JPanel {

private ChatBox box = new ChatBox(this);

public void OnTextSet(String s) {
    System.out.println(s);
}

public MessageWindow() {
    JTextArea messagePane = new JTextArea();

    setLayout(new GridBagLayout());

    GridBagConstraints gc = new GridBagConstraints();

    gc.weightx = 1;
    gc.weighty = 1;
    gc.fill = GridBagConstraints.BOTH;
    gc.insets = new Insets(5, 5, 5, 5);
    add(new JScrollPane(messagePane), gc);

    System.out.println(box.getText()); // Getting null in the console.
    messagePane.append(box.getText()); // Not getting anything on
                                        // messagePane.

}

}

And

public class ChatBox extends JPanel {

private JScrollPane scrollPane;
private String sendText = "";
private MessageWindow mw;

public ChatBox() {
    final JTextArea chatPane = new JTextArea();

    scrollPane = new JScrollPane(chatPane,
            JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
            JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
    add(scrollPane);
    scrollPane.setMinimumSize(new Dimension(550, 50));
    scrollPane.setPreferredSize(new Dimension(550, 50));

    chatPane.addKeyListener(new KeyListener() {

        @Override
        public void keyPressed(KeyEvent e) {
        }

        @Override
        public void keyReleased(KeyEvent e) {
            if (e.getKeyCode() == KeyEvent.VK_ENTER) {
                sendText = chatPane.getText();
                setText(sendText);
                chatPane.setText(null);
                mw.OnTextSet(sendText);
                // System.out.println(sendText); // I can see this in
                // console
            }

        }

        @Override
        public void keyTyped(KeyEvent e) {
        }

    });

}

public ChatBox(MessageWindow mw) {
    this.mw = mw;
}


public String getText() {
    return sendText;
}

public void setText(String sendText) {
    this.sendText = sendText;
}

}

Answer 1

You need a link from the Chatbox to the MessageWindow, inorder to send messages back and forth.

What could be done is modify as below

private ChatBox box = new ChatBox(this); //is this legal in java?
                                  ^^^^
public void OnTextSet(String s){
    System.out.println(s);      
}

//elsewhere
private MessageWindow mw;
public ChatBox(MessageWindow mw) {
               ^^^^^^^^^^^^^^^^
   this.mw = mw

...
public void keyReleased(KeyEvent e) {
...
   mw.OnTextSet(sendText);
}

Now type something and you should see the print out

Answer 2

The variable sendText in ChatBox class isn't initialized on creation. Since keyReleased event is not fired yet, sendText stays NULL. Try to modifiy from your code in Chatbox

from:

private String sendText;

to:

private String sendText = "";