How do I set the tab size in JTextArea?

By I Wayan Saryada in Swing 0 Comment

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 used 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.swing;

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

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

    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(TextAreaSetTabSize::showFrame);
    }

    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(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);
    }
}

The output of the code snippet above is:

JTextArea Tab Size Demo

How do I use the || operator in Java?

By I Wayan Saryada in Basic, Core API 0 Comment

The || operator or conditional OR operator operates on two boolean expressions. This operator exhibit “short-circuiting” behavior, which means that the second operand is evaluated only if needed.

The || operator evaluate only boolean values. For an OR (||) expression it will return true if either of the operand is true. If the first operand resolves true, then the second operand will not evaluate, because the complete expression will return true.

package org.kodejava.basic;

public class ConditionalORDemo {
    public static void main(String[] args) {
        // the second operand (5<3) is not evaluated, because the
        // first operand return true, the result of complete
        // expression will be true
        boolean a = (1 == 1) || (5 < 3);

        // the first operand return false, the second operand is
        // evaluated to check the result of the second expression.
        // If the second operand resolves to true, the complete
        // expression return true, otherwise return false.
        boolean b = (5 < 3) || (2 == 3);
        boolean c = (5 < 3) || (1 == 1);

        System.out.println("result a: " + a);
        System.out.println("result b: " + b);
        System.out.println("result c: " + c);
    }
}

The program prints the following output:

result a: true
result b: false
result c: true

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

By I Wayan Saryada 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 I Wayan Saryada 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 I Wayan Saryada 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.