How to implement the hashCode and equals method using Apache Commons?

By I Wayan Saryada in Apache Commons, Commons Lang 0 Comment 
package org.kodejava.commons.lang;

public class ObjectHashCodeDemo {

    public static void main(String[] args) {
        Book book1 = new Book(1L, "Spring Boot in Action", "Craig Walls");
        Book book2 = new Book(2L, "Docker in Action", "Jeff Nickoloff");
        Book book3 = book1;

        System.out.println("book1.hashCode() = " + book1.hashCode());
        System.out.println("book2.hashCode() = " + book2.hashCode());
        System.out.println("book3.hashCode() = " + book3.hashCode());
    }
}

package org.kodejava.commons.lang;

import org.apache.commons.lang3.builder.EqualsBuilder;
import org.apache.commons.lang3.builder.HashCodeBuilder;

import java.io.Serializable;

public class Book implements Serializable {
    private Long id;
    private String title;
    private String author;

    public Book(Long id, String title, String author) {
        this.id = id;
        this.title = title;
        this.author = author;
    }

    //~ Implements getters and setters here.

    public boolean equals(Object o) {
        if (o == this) {
            return true;
        }

        if (!(o instanceof Book)) {
            return false;
        }

        Book that = (Book) o;
        return new EqualsBuilder()
            .append(this.id, that.id)
            .append(this.title, that.title)
            .append(this.author, that.author)
            .isEquals();

        // You can also use reflection of the EqualsBuilder class.
        // return EqualsBuilder.reflectionEquals(this, that);
    }

    public int hashCode() {
        return new HashCodeBuilder()
            .append(id)
            .append(title)
            .append(author)
            .toHashCode();

        // Or even use the simplest method using reflection below.
        // return HashCodeBuilder.reflectionHashCode(this);
    }
}

Maven Dependencies

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-lang3</artifactId>
    <version>3.14.0</version>
</dependency>

Maven Central

How to establish connection to a database using Properties object?

By I Wayan Saryada in JDBC 0 Comment

In the following code snippet, you will see how to pass some connection arguments when connecting to a database. To do this, we can use the java.util.Properties class. We can put some key value pairs as a connection arguments to the Properties object
before we pass this information into the DriverManager class.

Let’s see the example below:

package org.kodejava.jdbc;

import java.sql.*;
import java.util.Properties;

public class GetConnectionWithProperties {
    private static final String URL = "jdbc:mysql://localhost/kodejava";
    private static final String USERNAME = "kodejava";
    private static final String PASSWORD = "s3cr*t";

    public static void main(String[] args) {
        GetConnectionWithProperties demo = new GetConnectionWithProperties();
        try (Connection connection = demo.getConnection()) {
            // do something with the connection.
            Statement stmt = connection.createStatement();
            ResultSet rs = stmt.executeQuery("SELECT * FROM product");
            while (rs.next()) {
                System.out.println("Code = " + rs.getString("code"));
                System.out.println("Name = " + rs.getString("name"));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    private Connection getConnection() throws SQLException {
        Properties connectionProps = new Properties();
        connectionProps.put("user", USERNAME);
        connectionProps.put("password", PASSWORD);

        Connection connection = DriverManager.getConnection(URL, connectionProps);
        System.out.println("Connected to database.");
        return connection;
    }
}

Maven Dependencies

<dependency>
    <groupId>com.mysql</groupId>
    <artifactId>mysql-connector-j</artifactId>
    <version>8.4.0</version>
</dependency>

Maven Central

How to get random key-value pair from Hashtable?

By I Wayan Saryada in Core API, Util Package 0 Comment 
package org.kodejava.example.util;

import java.util.Hashtable;
import java.util.Random;

public class HashtableGetRandom {
    public static void main(String[] args) {
        // Create a hashtable and put some key-value pair.
        Hashtable<String, String> colors = new Hashtable<>();
        colors.put("black", "#000");
        colors.put("red", "#f00");
        colors.put("green", "#0f0");
        colors.put("blue", "#00f");
        colors.put("white", "#fff");

        // Get a random entry from the hashtable.
        String[] keys = colors.keySet().toArray(new String[colors.size()]);
        String key = keys[new Random().nextInt(keys.length)];
        System.out.println(key + " = " + colors.get(key));
    }
}

How to truncate a string after n number of words?

By I Wayan Saryada in Regex 1 Comment 
package org.kodejava.regex;

public class GetNumberOfWordsFromString {
    public static void main(String[] args) {
        String text = "The quick brown fox jumps over the lazy dog.";

        String one = truncateAfterWords(1, text);
        System.out.println("1 = " + one);

        String two = truncateAfterWords(2, text);
        System.out.println("2 = " + two);

        String four = truncateAfterWords(4, text);
        System.out.println("4 = " + four);

        String six = truncateAfterWords(6, text);
        System.out.println("6 = " + six);
    }

    /**
     * Truncate a string after n number of words.
     *
     * @param words number of words to truncate after.
     * @param text  the text.
     * @return truncated text.
     */
    public static String truncateAfterWords(int words, String text) {
        String regex = String.format("^((?:\\W*\\w+){%s}).*$", words);
        return text.replaceAll(regex, "$1");
    }
}

The result of the snippet:

1 = The
2 = The quick
4 = The quick brown fox
6 = The quick brown fox jumps over

How to define JRadioButton label position?

By I Wayan Saryada in Swing 0 Comment

In this code snippet you’ll see how to define JRadioButton label position. By default, the label will be displayed on the right side of the button. In the code below you will see some examples for placing the label on the left side, at the top and the bottom of the JRadioButton.

To define the label position we use the combination of the setHorizontalTextPosition() and setVerticalTextPosition() method and specified the position using one of the available constant in SwingConstants interface.

package org.kodejava.swing;

import javax.swing.*;

public class RadioButtonLabelPosition {
    public static void main(String[] args) {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        JPanel panel = new JPanel();

        // Create JRadioButton with label on the right
        JRadioButton button1 = new JRadioButton("Button One");
        button1.setHorizontalTextPosition(SwingConstants.RIGHT);

        // Create JRadioButton with label on the left
        JRadioButton button2 = new JRadioButton("Button Two");
        button2.setHorizontalTextPosition(SwingConstants.LEFT);

        // Create JRadioButton with label at the bottom centered.
        JRadioButton button3 = new JRadioButton("Button Three");
        button3.setVerticalTextPosition(SwingConstants.BOTTOM);
        button3.setHorizontalTextPosition(SwingConstants.CENTER);

        // Create JRadioButton with label at the top centered.
        JRadioButton button4 = new JRadioButton("Button Four");
        button4.setVerticalTextPosition(SwingConstants.TOP);
        button4.setHorizontalTextPosition(SwingConstants.CENTER);

        panel.add(button1);
        panel.add(button2);
        panel.add(button3);
        panel.add(button4);

        frame.add(panel);
        frame.setSize(500, 300);
        frame.setVisible(true);
    }
}

Here is a screen capture result of the code snippet above:

JRadioButton Label Position