How do I create a single line JTextArea?

The following example will show you how to create a single line JTextArea. A single line means that you cannot insert a new line in the text area. When pressing the enter key it will be replaced by a space.

This can be done by putting a property called filterNewlines and set its value to Boolean.TRUE into the document model of the JTextArea.

package org.kodejava.example.swing;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class SingleLineTextArea extends JFrame {
    private SingleLineTextArea() {
        initialize();
    }

    private void initialize() {
        setSize(300, 300);
        setTitle("Single Line Text Area");
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setLayout(new BorderLayout());

        final JTextArea textArea = new JTextArea();
        textArea.setLineWrap(true);

        // Filter a new line, pressing enter key will be replaced
        // with a space instead.
        textArea.getDocument().putProperty("filterNewlines",
                Boolean.TRUE);

        JScrollPane scrollPane = new JScrollPane(textArea);

        // Pressing the Save button print out the text area text
        // into the console.
        JButton button = new JButton("Save");
        button.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                System.out.println(textArea.getText());
            }
        });
        getContentPane().add(scrollPane, BorderLayout.CENTER);
        getContentPane().add(button, BorderLayout.SOUTH);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new SingleLineTextArea().setVisible(true);
            }
        });
    }
}

Single Line TextArea

How do I move focus from JTextArea using TAB key?

The default behavior when pressing the tabular key in a JTextArea is to insert a tab spaces in the text area. In this example you’ll see how to change this to make the tab key to transfer focus to other component forward or backward.

The main routine can be found in the key listener section. When the tab key is pressed we will tell the text area to transfer to focus into other component. Let’s see the code snippet below.

package org.kodejava.example.swing;

import javax.swing.*;
import java.awt.*;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;

public class TextAreaTabMoveFocus extends JFrame {
    public TextAreaTabMoveFocus() {
        initialize();
    }

    private void initialize() {
        setSize(300, 300);
        setTitle("JTextArea TAB DEMO");
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setLayout(new BorderLayout());

        JTextField textField = new JTextField();
        JPasswordField passwordField = new JPasswordField();
        final JTextArea textArea = new JTextArea();
        JScrollPane scrollPane = new JScrollPane(textArea);

        // Add key listener to change the TAB behavior in
        // JTextArea to transfer focus to other component forward
        // or backward.
        textArea.addKeyListener(new KeyAdapter() {
            @Override
            public void keyPressed(KeyEvent e) {
                if (e.getKeyCode() == KeyEvent.VK_TAB) {
                    if (e.getModifiers() > 0) {
                        textArea.transferFocusBackward();
                    } else {
                        textArea.transferFocus();
                    }
                    e.consume();
                }
            }
        });

        getContentPane().add(textField, BorderLayout.NORTH);
        getContentPane().add(scrollPane, BorderLayout.CENTER);
        getContentPane().add(passwordField, BorderLayout.SOUTH);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new TextAreaTabMoveFocus().setVisible(true);
            }
        });
    }
}

How do I disable keyboard events in JTextArea?

The following example demonstrate how to disable some keys in JTextArea and JScrollPane using the InputMap. In the disableKeys() method below we disable the arrow keys including the UP, DOWN, LEFT and RIGHT.

Let’s see the code snippet below:

package org.kodejava.example.swing;

import javax.swing.*;
import java.awt.*;

public class DisableKeyDemo extends JFrame {
    public DisableKeyDemo() {
        initialize();
    }

    private void initialize() {
        setSize(300, 300);
        setTitle("Disable Keys Demo");
        setLayout(new BorderLayout());
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        JTextArea textArea = new JTextArea("Hello World!");
        JScrollPane scrollPane = new JScrollPane(textArea);
        disableKeys(textArea.getInputMap());
        disableKeys(scrollPane.getInputMap(
                JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT));

        getContentPane().add(scrollPane, BorderLayout.CENTER);
    }

    private void disableKeys(InputMap inputMap) {
        String[] keys = {"UP", "DOWN", "LEFT", "RIGHT"};
        for (String key : keys) {
            inputMap.put(KeyStroke.getKeyStroke(key), "none");
        }
    }

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