How do I use the boolean negation (!) operator in Java?

By Wayan in Basic, Core API 0 Comment

The ! operator is a logical compliment operator. The operator inverts the value of a boolean expression.

package org.kodejava.basic;

public class NegationOperator {
    public static void main(String[] args) {
        // negate the result of boolean expressions
        boolean negate = !(2 < 3);
        boolean value = !false;

        System.out.println("result: " + negate);
        System.out.println("value : " + value);
    }
}

Here is the result of the program:

result: false
value : true

How do I wrap the text lines in JTextArea?

By Wayan in Swing 0 Comment

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.swing;

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

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

    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(TextAreaWrapDemo::showFrame);
    }

    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);
    }
}

The output of the code snippet above is:

JTextArea Wrap Text Line Demo

How do I match a regex pattern in case-insensitive?

By Wayan in Regex 0 Comment

Finding the next subsequence of the input sequence that matches the pattern while ignoring the case of the string in regular expression can simply apply by create a pattern using compile(String regex, int flags) method and specifies a second argument with PATTERN.CASE_INSENSITIVE constant.

package org.kodejava.regex;

import java.util.regex.Pattern;
import java.util.regex.Matcher;

public class RegexIgnoreCaseDemo {
    public static void main(String[] args) {
        String sentence =
                "The quick brown fox and BROWN tiger jumps over the lazy dog";

        Pattern pattern = Pattern.compile("brown", Pattern.CASE_INSENSITIVE);
        Matcher matcher = pattern.matcher(sentence);

        while (matcher.find()) {
            System.out.format("Text \"%s\" found at %d to %d.%n",
                    matcher.group(), matcher.start(), matcher.end());
        }
    }
}

Here is the result of the program:

Text "brown" found at 10 to 15.
Text "BROWN" found at 24 to 29.

How do I set the font and color of JTextArea?

By Wayan in Swing 0 Comment

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.swing;

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

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

    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(TextAreaFontDemo::showFrame);
    }

    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);
    }
}

Here is the program screenshot of the code snippet above:

JTextArea Font and Color Demo

How do I create an uneditable JTextArea?

By Wayan in Swing 1 Comment

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.swing;

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

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

    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(TextAreaNotEditable::showFrame);
    }

    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);
    }
}

The output of the code snippet is:

Uneditable JTextArea Demo