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

How do I use the relational operator in Java?

By Wayan in Basic, Core API 0 Comment

Relational operators used to compare any combination of integers, floating-point numbers, or characters. The result of relational operators is always in a boolean value, true or false. It is mostly used in an if statement test.

There are four relational operators in Java:

  • > greater than
  • >= greater than or equal to
  • < less than
  • <= less than or equal to
package org.kodejava.basic;

public class RelationalDemo {
    public static void main(String[] args) {
        int value1 = 10, value2 = 25;
        int age = 15;
        double salary = 1000d;
        char char1 = 'd', char2 = 'f';

        if (value1 > value2) {
            System.out.format("%d is greater than %d %n", value1, value2);
        } else {
            System.out.format("%d is greater than %d %n", value2, value1);
        }

        if (age >= 12) {
            System.out.format("Hey, I am not a kid anymore %n");
        }

        if (char1 < char2) {
            System.out.format("%c is less than %c %n", char1, char2);
        } else {
            System.out.format("%c is less than %c %n", char2, char1);
        }

        if (salary <= 3000d) {
            System.out.println("Entry-level Staff");
        }
    }
}

An here are the result of the program:

25 is greater than 10 
Hey, I am not a kid anymore 
d is less than f 
Entry-level Staff

How do I use the equality operator in Java?

By Wayan in Basic, Core API 0 Comment

Equality operator is used to compare two similar things (numbers, characters, boolean, primitives and object references). Equality operator will always result in boolean value (true or false).

For object reference, it will return true if only both reference variables refer to the same object.

package org.kodejava.basic;

public class EqualityDemo {
    public static void main(String[] args) {
        int value1 = 10, value2 = 10, number1 = 10;
        char a = 'a', b = 'b';
        double number2 = 10d;
        Cat kitty = new Cat("Kitty");
        Cat kitten = new Cat("Kitty");
        Cat sweetie = kitty;

        if (value1 == value2) {
            System.out.println("Equal");
        }

        if (a != b) {
            System.out.println("Not Equal");
        }

        // though it have different type, but it have same value
        if (number1 == number2) {
            System.out.println("Equal");
        }

        // it's not refer to the same object, so it will return
        // false
        if (kitty == kitten) {
            System.out.format("(kitty == kitten) = " + (kitty == kitten));
        } else {
            System.out.println("(kitty == kitten) = " + (kitty == kitten));
        }

        // it's refer to the same object, so it will return true
        if (kitty == sweetie) {
            System.out.println("(kitty == sweetie) = " + (kitty == sweetie));
        }

        if (true != false) {
            System.out.println("true != false");
        }

    }
}

class Cat {
    private String name;

    Cat(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

And here are the result of the program:

Equal
Not Equal
Equal
(kitty == kitten) = false
(kitty == sweetie) = true
true != false