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(500, 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(500, 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 screenshot of the code snippet above:

JTextArea Select All Text

How do I append text to JTextArea?

To append text to the end of the JTextArea document we can use the append(String str) method. This method does nothing if the document is null or the string is null or empty.

package org.kodejava.example.swing;

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

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

    private void initializeUI() {
        String text = "The quick brown fox ";

        JTextArea textArea = new JTextArea(text);
        textArea.setLineWrap(true);
        textArea.setWrapStyleWord(true);
        JScrollPane scrollPane = new JScrollPane(textArea);

        String appendText = "jumps over the lazy dog.";
        textArea.append(appendText);

        this.setPreferredSize(new Dimension(500, 200));
        this.setLayout(new BorderLayout());
        this.add(scrollPane, BorderLayout.CENTER);
    }

    public static void showFrame() {
        JPanel panel = new TextAreaAppendText();
        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() {
                TextAreaAppendText.showFrame();
            }
        });
    }
}

The output of the code snippet above is:

JTextArea Append Text Demo

How do I set and get the contents of JTextArea?

To set and get the contents of a JTextArea you can use the setText(String text) and getText() methods. In the code below we create a JTextArea and sets its contents after we create a new instance of JTextArea. To get the contents we use the action on a button. When the button is pressed the contents of the JTextArea is read using the getText() method. This method return a String object.

package org.kodejava.example.swing;

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

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

    private void initializeUI() {
        this.setLayout(new BorderLayout());
        this.setPreferredSize(new Dimension(500, 200));

        final JTextArea textArea = new JTextArea();

        // Set the contents of the JTextArea.
        String text = "The quick brown fox jumps over the lazy dog.";
        textArea.setText(text);
        textArea.setLineWrap(true);
        textArea.setWrapStyleWord(true);

        JScrollPane pane = new JScrollPane(textArea);
        pane.setPreferredSize(new Dimension(500, 200));
        pane.setVerticalScrollBarPolicy(
            JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);

        JButton button = new JButton("Get Contents");
        button.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                // Get the contents of the JTextArea component.
                String contents = textArea.getText();
                System.out.println("contents = " + contents);
            }
        });

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

    public static void showFrame() {
        JPanel panel = new TextAreaGetContent();
        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() {
                TextAreaGetContent.showFrame();
            }
        });
    }
}

The output of the code snippet above is:

Set and Get the Content of JTextArea

How do I set the tab size in JTextArea?

In this example you will be shown how to set or change the tab size for the JTextArea component. You can use the setTabSize(int size) to define the tab size. For this demo we create a combo box that have some integer values which will be use to define the tab size. When you change the selected item in the combo box the JTextArea tab size will be change immediately.

package org.kodejava.example.swing;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;

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

    private void initializeUI() {
        this.setLayout(new BorderLayout());
        this.setPreferredSize(new Dimension(500, 200));

        JLabel label = new JLabel("Tab size: ");
        Object[] items = {2, 4, 8, 10, 20};
        final JComboBox<Object> comboBox = new JComboBox<>(items);

        JPanel tabPanel = new JPanel(new FlowLayout());
        tabPanel.add(label);
        tabPanel.add(comboBox);

        this.add(tabPanel, BorderLayout.NORTH);

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

        // Sets the number of characters to expand tabs to.
        textArea.setTabSize((Integer) comboBox.getSelectedItem());
        comboBox.addItemListener(new ItemListener() {
            public void itemStateChanged(ItemEvent e) {
                textArea.setTabSize((Integer) comboBox.getSelectedItem());
            }
        });

        JScrollPane pane = new JScrollPane(textArea);
        pane.setPreferredSize(new Dimension(500, 200));
        pane.setVerticalScrollBarPolicy(
            JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);

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

    public static void showFrame() {
        JPanel panel = new TextAreaSetTabSize();
        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() {
                TextAreaSetTabSize.showFrame();
            }
        });
    }
}

The output of the code snippet above is:

JTextArea Tab Size Demo

How do I wrap the text lines in JTextArea?

To wrap the lines of JTextArea we need to call the setLineWrap(boolean wrap) method and pass a true boolean value as the parameter. The setWrapStyleWord(boolean word) method wrap the lines at word boundaries when we set it to true.

package org.kodejava.example.swing;

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

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

    private void initializeUI() {
        this.setLayout(new BorderLayout());
        this.setPreferredSize(new Dimension(500, 200));

        JTextArea textArea = new JTextArea(5, 40);

        String text = "The quick brown fox jumps over the lazy dog. " +
            "The quick brown fox jumps over the lazy dog. " +
            "The quick brown fox jumps over the lazy dog.";
        textArea.setText(text);
        textArea.setFont(new Font("Arial", Font.BOLD, 18));

        // Wrap the lines of the JTextArea if it does not fit in the
        // current allocated with of the JTextArea.
        textArea.setLineWrap(true);
        textArea.setWrapStyleWord(true);
        JScrollPane scrollPane = new JScrollPane(textArea);

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

    public static void showFrame() {
        JPanel panel = new TextAreaWrapDemo();
        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() {
                TextAreaWrapDemo.showFrame();
            }
        });
    }
}

The output of the code snippet above is:

JTextArea Wrap Text Line Demo

How do I set the font and color of JTextArea?

To set the font and color of JTextArea we can use the setFont() and setForeground() methods of the JTextArea. To create a font we must define the font name, the font style and its size. For the colors we can uses the constant color values defined by the Color class.

package org.kodejava.example.swing;

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

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

    private void initializeUI() {
        this.setLayout(new BorderLayout());
        this.setPreferredSize(new Dimension(500, 200));

        JTextArea textArea = new JTextArea(5, 40);
        textArea.setLineWrap(true);
        textArea.setText("The quick brown fox jumps over the lazy dog.");

        // Sets JTextArea font and color.
        Font font = new Font("Segoe Script", Font.BOLD, 20);
        textArea.setFont(font);
        textArea.setForeground(Color.BLUE);
        JScrollPane scrollPane = new JScrollPane(textArea);

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

    private static void showFrame() {
        JPanel panel = new TextAreaFontDemo();
        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() {
                TextAreaFontDemo.showFrame();
            }
        });
    }
}

Here is the program screenshot of the code snippet above:

JTextArea Font and Color Demo

How do I create an uneditable JTextArea?

The following example shows you how to set the property of the JTextArea so that it cannot be edited or modified. To make the JTextArea not editable call the setEditable() method and pass a false value as the parameter.

package org.kodejava.example.swing;

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

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

    private void initializeUI() {
        this.setLayout(new BorderLayout());
        this.setPreferredSize(new Dimension(500, 200));

        JTextArea textArea = new JTextArea(5, 50);
        textArea.setText("The quick brown fox jumps over the lazy dog.");

        // By default the JTextArea is editable, calling
        // setEditable(false) produce uneditable JTextArea.
        textArea.setEditable(false);
        JScrollPane scrollPane = new JScrollPane(textArea);

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

    public static void showFrame() {
        JPanel panel = new TextAreaNotEditable();
        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() {
                TextAreaNotEditable.showFrame();
            }
        });
    }
}

The output of the code snippet is:

Uneditable JTextArea Demo

How do I create a JTextArea?

This example shows you how to create a simple JTextArea component in Java Swing application. First you’ll create an instance of JTextAread and passes the number of rows and columns. Next to add a scroll ability you can wrap the component inside a JScrollPane.

package org.kodejava.example.swing;

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

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

    private void initializeUI() {
        this.setLayout(new BorderLayout());
        this.setPreferredSize(new Dimension(500, 200));

        // Creates a JTextArea with 5 rows and 40 columns. Then
        // wrap the JTextArea inside a JScrollPane for adding
        // scrolling abilities.
        JTextArea textArea = new JTextArea(5, 50);
        JScrollPane scrollPane = new JScrollPane(textArea);

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

    public static void showFrame() {
        JPanel panel = new TextAreaDemo();
        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() {
                TextAreaDemo.showFrame();
            }
        });
    }
}

The result of our code snippet is:

Swing JTextArea Demo

How do I remove tabs from JTabbedPane?

To remove tabs from JTabbedPane we can use the following remove methods:

  • remove(int index) method to remove a tab at the specified index.
  • remove(Component component) method to remove a tab that has the specified child component.
  • removeAll() method to remove all tabs.
package org.kodejava.example.swing;

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

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

    private void initializeUI() {
        final JTabbedPane pane = new JTabbedPane(JTabbedPane.LEFT);
        pane.addTab("A Tab", new JPanel());
        pane.addTab("B Tab", new JPanel());

        JPanel tabPanel = new JPanel();
        pane.addTab("C Tab", tabPanel);
        pane.addTab("D Tab", new JPanel());
        pane.addTab("E Tab", new JPanel());

        // Remove the last tab from JTabbedPane
        pane.remove(pane.getTabCount() - 1);

        // Remove tab that contains a tabPanel component which is
        // the C Tab.
        pane.remove(tabPanel);

        JButton button = new JButton("Remove All Tabs");
        button.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                // Remove all tabs from JTabbedPane
                pane.removeAll();
            }
        });

        this.setLayout(new BorderLayout());
        this.setPreferredSize(new Dimension(500, 200));
        this.add(pane, BorderLayout.CENTER);
        this.add(button, BorderLayout.SOUTH);
    }

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

        JFrame frame = new JFrame("JTabbedPane 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() {
                TabbedPaneRemoveTab.showFrame();
            }
        });
    }
}

The output of the code snippet above is:

Remove Tabs from JTabbedPane

How do I assign keyboard shortcut to JTabbedPane tabs?

To assign a keyboard shortcut for accessing JTabbedPane‘s tab you can use the setMnemonicAt(int tabIndex, int mnemonic) method of the JTabbedPane class. The tabIndex parameter is a zero-based value parameter which means that the first tab is at index number 0. For the mnenomic parameter you can use constants value defined in the java.awt.event.KeyEvent class.

Here is an example in action on how to assign keyboard shortcut to JTabbedPane‘s tabs. To access the tabs you can use the ALT + A, ALT + B, ALT + C and ALT + D keyboard combination.

package org.kodejava.example.swing;

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

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

    private void initializeUI() {
        this.setLayout(new BorderLayout());
        this.setPreferredSize(new Dimension(500, 200));

        JTabbedPane pane = new JTabbedPane();
        pane.addTab("A Tab", new JPanel());
        pane.addTab("B Tab", new JPanel());
        pane.addTab("C Tab", new JPanel());
        pane.addTab("D Tab", new JPanel());

        pane.setMnemonicAt(0, KeyEvent.VK_A);
        pane.setMnemonicAt(1, KeyEvent.VK_B);
        pane.setMnemonicAt(2, KeyEvent.VK_C);
        pane.setMnemonicAt(3, KeyEvent.VK_D);

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

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

        JFrame frame = new JFrame("JTabbedPane 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() {
                TabbedPaneKeyboardShortcut.showFrame();
            }
        });
    }
}

The output of the code snippet above is:

JTabbedPane Tabs with Keyboard Shortcut