Hi guys i am writing a chat-server project in java.In my client program i use two text areas.One to show the conversation between clients and the other to input for the client's message. At first i used a TextField but i want multiple lines for input so i finally used textarea as there isnt another choice for multiple lines..When send button is clicked or button enter is pushed i want to get the text and send it ..I already know the code to send it and all the other stuff but each time i try to add actionListener to the textarea, compiler doesnt allow me by saying that it is not define for textareas , i thought i would do the same as if with textfield something like that:
ActionListener sendListener = new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (e.getSource() == sendButton){
String str = inputTextArea.getText();}
}
};
and then
inputTextArea.addActionListener(sendListener);
any help please..
As you're finding out, you can't add an ActionListener to a JTextArea. Your best bet is to use Key Bindings to bind to JTextArea's the VK_ENTER KeyStroke, and put your code in the AbstractAction that you use for the binding. The Key Binding tutorial will show you the details: Key Binding Tutorial
For example:
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import javax.swing.*;
@SuppressWarnings("serial")
public class KeyBindingEg extends JPanel {
private static final int LARGE_TA_ROWS = 20;
private static final int TA_COLS = 40;
private static final int SMALL_TA_ROWS = 3;
private JTextArea largeTextArea = new JTextArea(LARGE_TA_ROWS, TA_COLS);
private JTextArea smallTextArea = new JTextArea(SMALL_TA_ROWS, TA_COLS);
private Action submitAction = new SubmitAction("Submit", KeyEvent.VK_S);
private JButton submitButton = new JButton(submitAction);
public KeyBindingEg() {
// set up key bindings
int condition = JComponent.WHEN_FOCUSED; // only bind when the text area is focused
InputMap inputMap = smallTextArea.getInputMap(condition);
ActionMap actionMap = smallTextArea.getActionMap();
KeyStroke enterStroke = KeyStroke.getKeyStroke(KeyEvent.VK_ENTER, 0);
inputMap.put(enterStroke, enterStroke.toString());
actionMap.put(enterStroke.toString(), submitAction);
// set up GUI
largeTextArea.setFocusable(false); // this is for display only
largeTextArea.setWrapStyleWord(true);
largeTextArea.setLineWrap(true);
smallTextArea.setWrapStyleWord(true);
smallTextArea.setLineWrap(true);
JScrollPane largeScrollPane = new JScrollPane(largeTextArea);
JScrollPane smallScrollPane = new JScrollPane(smallTextArea);
largeScrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
smallScrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
JPanel bottomPanel = new JPanel(new BorderLayout());
bottomPanel.add(smallScrollPane, BorderLayout.CENTER);
bottomPanel.add(submitButton, BorderLayout.LINE_END);
setBorder(BorderFactory.createEmptyBorder(3, 3, 3, 3));
setLayout(new BorderLayout(3, 3));
add(largeScrollPane, BorderLayout.CENTER);
add(bottomPanel, BorderLayout.PAGE_END);
}
private class SubmitAction extends AbstractAction {
public SubmitAction(String name, int mnemonic) {
super(name);
putValue(MNEMONIC_KEY, mnemonic);
}
@Override
public void actionPerformed(ActionEvent e) {
String text = smallTextArea.getText();
smallTextArea.selectAll(); // keep text, but make it easy to replace
// smallTextArea.setText(""); // or if you want to clear the text
smallTextArea.requestFocusInWindow();
// TODO: send text to chat server here
// record text in our large text area
largeTextArea.append("Me> ");
largeTextArea.append(text);
largeTextArea.append("\n");
}
}
private static void createAndShowGui() {
JFrame frame = new JFrame("Key Binding Eg");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new KeyBindingEg());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}
Edit: new version now allow the Ctrl-Enter key combination to work as the Enter key originally did. This works by mapping the Action originally mapped to the Enter keystroke now to the Ctrl-Enter keystroke:
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.InputEvent;
import java.awt.event.KeyEvent;
import javax.swing.*;
@SuppressWarnings("serial")
public class KeyBindingEg extends JPanel {
private static final int LARGE_TA_ROWS = 20;
private static final int TA_COLS = 40;
private static final int SMALL_TA_ROWS = 3;
private JTextArea largeTextArea = new JTextArea(LARGE_TA_ROWS, TA_COLS);
private JTextArea smallTextArea = new JTextArea(SMALL_TA_ROWS, TA_COLS);
private Action submitAction = new SubmitAction("Submit", KeyEvent.VK_S);
private JButton submitButton = new JButton(submitAction);
public KeyBindingEg() {
// set up key bindings
int condition = JComponent.WHEN_FOCUSED; // only bind when the text area
// is focused
InputMap inputMap = smallTextArea.getInputMap(condition);
ActionMap actionMap = smallTextArea.getActionMap();
// get enter and ctrl-enter keystrokes
KeyStroke enterStroke = KeyStroke.getKeyStroke(KeyEvent.VK_ENTER, 0);
KeyStroke ctrlEnterStroke = KeyStroke.getKeyStroke(KeyEvent.VK_ENTER, InputEvent.CTRL_DOWN_MASK);
// get original input map key for the enter keystroke
String enterKey = (String) inputMap.get(enterStroke);
// note that there is no key in the map for the ctrl-enter keystroke --
// it is null
// extract the old action for the enter key stroke
Action oldEnterAction = actionMap.get(enterKey);
actionMap.put(enterKey, submitAction); // substitute our new action
// put the old enter Action back mapped to the ctrl-enter key
inputMap.put(ctrlEnterStroke, ctrlEnterStroke.toString());
actionMap.put(ctrlEnterStroke.toString(), oldEnterAction);
largeTextArea.setFocusable(false); // this is for display only
largeTextArea.setWrapStyleWord(true);
largeTextArea.setLineWrap(true);
smallTextArea.setWrapStyleWord(true);
smallTextArea.setLineWrap(true);
JScrollPane largeScrollPane = new JScrollPane(largeTextArea);
JScrollPane smallScrollPane = new JScrollPane(smallTextArea);
largeScrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
smallScrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
JPanel bottomPanel = new JPanel(new BorderLayout());
bottomPanel.add(smallScrollPane, BorderLayout.CENTER);
bottomPanel.add(submitButton, BorderLayout.LINE_END);
setBorder(BorderFactory.createEmptyBorder(3, 3, 3, 3));
setLayout(new BorderLayout(3, 3));
add(largeScrollPane, BorderLayout.CENTER);
add(bottomPanel, BorderLayout.PAGE_END);
}
private class SubmitAction extends AbstractAction {
public SubmitAction(String name, int mnemonic) {
super(name);
putValue(MNEMONIC_KEY, mnemonic);
}
@Override
public void actionPerformed(ActionEvent e) {
String text = smallTextArea.getText();
smallTextArea.selectAll(); // keep text, but make it easy to replace
// smallTextArea.setText(""); // or if you want to clear the text
smallTextArea.requestFocusInWindow();
// TODO: send text to chat server here
// record text in our large text area
largeTextArea.append("Me> ");
largeTextArea.append(text);
largeTextArea.append("\n");
}
}
private static void createAndShowGui() {
JFrame frame = new JFrame("Key Binding Eg");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new KeyBindingEg());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}