JTextArea pressing enter adds unnecessary new line

Question

I'm developing a chat application and when I press an enter button when focusing the JTextArea I want it to stop adding the unnecessary new line of text, so for example i will be able to determine when user has pressed the enter button and not typed anything inside the JTextArea. I am using a KeyListener for the means of detecting when an user has released the enter key and then sending the message. I firstly tried replacing the new line of text with an empty string message.replaceAll("[\n]", "") and also trimming the message, however it didn't work. Is there anything i'm doing wrong with my approach or would there be any other solution i could adapt?

Answer 1

• Don't use a JTextArea for this, but instead use a JTextField.
• You can then easily listen for the enter press by giving the JTextField an ActionListener.
• Most Swing chat applications I've seen use two text components for this: a JTextArea to display incoming text and your sent text, and a JTextField to allow user input of the text to send.

• Usually one is right on top of the other using a BorderLayout.

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• If you absolutely must use a JTextArea, then you will probably want to use Key Binding to capture the enter key and deal with it. Check out the How to use Key Bindings Tutorial.

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For example:

Example Key Bindings Solution:

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;

import javax.swing.*;

@SuppressWarnings("serial")
public class CaptureTextAreaEnter extends JPanel {
   private static final int COLS = 30;
   private static final int VIEW_ROWS = 12;
   private static final int ENTER_ROWS = 4;
   private JTextArea chatViewArea = new JTextArea(VIEW_ROWS, COLS);
   private JTextArea chatEnterArea = new JTextArea(ENTER_ROWS, COLS);

   public CaptureTextAreaEnter() {
      setLayout(new BorderLayout());
      add(new JScrollPane(chatViewArea), BorderLayout.CENTER);
      add(new JScrollPane(chatEnterArea), BorderLayout.SOUTH);

      chatViewArea.setFocusable(false);

      chatViewArea.setWrapStyleWord(true);
      chatEnterArea.setWrapStyleWord(true);
      chatViewArea.setLineWrap(true);
      chatEnterArea.setLineWrap(true);

      // start our set up of key bindings

      // to get the correct InputMap
      int condition = WHEN_FOCUSED;  
      // get our maps for binding from the chatEnterArea JTextArea
      InputMap inputMap = chatEnterArea.getInputMap(condition);
      ActionMap actionMap = chatEnterArea.getActionMap();

      // the key stroke we want to capture
      KeyStroke enterStroke = KeyStroke.getKeyStroke(KeyEvent.VK_ENTER, 0);

      // tell input map that we are handling the enter key
      inputMap.put(enterStroke, enterStroke.toString());

      // tell action map just how we want to handle the enter key
      actionMap.put(enterStroke.toString(), new AbstractAction() {

         @Override
         public void actionPerformed(ActionEvent arg0) {
            String text = chatEnterArea.getText();
            chatEnterArea.setText("");
            chatViewArea.append(text + "\n");

            // *** you will want to send text to your 
            // *** PrintStream to the chat server here 
         }
      });
   }

   private static void createAndShowGui() {
      CaptureTextAreaEnter mainPanel = new CaptureTextAreaEnter();

      JFrame frame = new JFrame("CaptureTextAreaEnter");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(mainPanel);
      frame.pack();
      frame.setLocationByPlatform(true);
      frame.setVisible(true);
   }

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