How do I select all text in JTextArea?

Selecting all text in the JTextArea component can be done by using the selectAll() method. In the example below we use a button action to do the selection. After select the text we transfer focus back to the JTextArea so that the highlighted text is shown.

package org.kodejava.example.swing;

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

public class TextAreaSelectAll extends JPanel {
    public TextAreaSelectAll() {
        initializeUI();
    }

    private void initializeUI() {
        this.setLayout(new BorderLayout());
        this.setPreferredSize(new Dimension(400, 200));

        final JTextArea textArea = new JTextArea(
                "The quick brown fox jumps over the lazy dog.");
        textArea.setLineWrap(true);
        textArea.setWrapStyleWord(true);

        JScrollPane pane = new JScrollPane(textArea);
        pane.setPreferredSize(new Dimension(400, 200));
        pane.setVerticalScrollBarPolicy(
                JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);

        final JButton button1 = new JButton("Select All");
        button1.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                textArea.selectAll();

                // Transfer focus to JTextArea to show the selected
                // text.
                button1.transferFocusBackward();
            }
        });
        final JButton button2 = new JButton("Get Selected Text");
        button2.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                String text = textArea.getSelectedText();
                System.out.println("Text = " + text);
            }
        });

        JPanel buttonPanel = new JPanel(new FlowLayout());
        buttonPanel.add(button1);
        buttonPanel.add(button2);

        this.add(pane, BorderLayout.CENTER);
        this.add(buttonPanel, BorderLayout.SOUTH);
    }

    public static void showFrame() {
        JPanel panel = new TextAreaSelectAll();
        panel.setOpaque(true);

        JFrame frame = new JFrame("JTextArea Demo");
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.setContentPane(panel);
        frame.pack();
        frame.setVisible(true);
    }

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

And here the screenshoot of the code snippet above: