How do I set the fetch mode for Criteria association?

By Wayan in Hibernate 0 Comment

o set the fetching mode for association we can call the Criteria‘s setFetchMode() method. We can use the FetchMode.SELECT or FetchMode.JOIN.

package org.kodejava.hibernate;

import org.hibernate.*;
import org.hibernate.cfg.Configuration;
import org.hibernate.criterion.Restrictions;
import org.kodejava.hibernate.model.Record;

import java.util.List;

public class FetchModeDemo {
    public static Session getSession() throws HibernateException {
        String cfg = "hibernate.cfg.xml";
        SessionFactory sessionFactory = new Configuration().configure(cfg)
                .buildSessionFactory();
        return sessionFactory.openSession();
    }

    @SuppressWarnings("unchecked")
    public static void main(String[] args) {
        try (Session session = getSession()) {
            Criteria criteria = session.createCriteria(Record.class)
                    .setFetchMode("artist", FetchMode.SELECT)
                    .setFetchMode("label", FetchMode.SELECT)
                    .add(Restrictions.like("title", "The Beatles%"));

            List<Record> records = criteria.list();
            for (Record record : records) {
                System.out.println("Recording  = "
                        + record.getTitle());
                System.out.println("Artist     = "
                        + record.getArtist().getName());
            }
        }
    }
}

Maven Dependencies

<dependencies>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>5.6.9.Final</version>
    </dependency>
    <dependency>
        <groupId>com.mysql</groupId>
        <artifactId>mysql-connector-j</artifactId>
        <version>8.0.33</version>
    </dependency>
</dependencies>

Maven Central Maven Central

How do I count the total records using Projections?

By Wayan in Hibernate 4 Comments

The example below show how to get total row count using the Projections.rowCount(). The result of this query will be a single object of Integer that contains the result of executing an SQL select count (*) command.

package org.kodejava.hibernate;

import org.hibernate.SessionFactory;
import org.hibernate.Session;
import org.hibernate.HibernateException;
import org.hibernate.Criteria;
import org.hibernate.cfg.Configuration;
import org.hibernate.criterion.Projections;
import org.kodejava.hibernate.model.Track;

import java.util.List;

public class ProjectionsCountDemo {
    public static Session getSession() throws HibernateException {
        String cfg = "hibernate.cfg.xml";
        SessionFactory sessionFactory = new Configuration().configure(cfg)
                .buildSessionFactory();
        return sessionFactory.openSession();
    }

    @SuppressWarnings("unchecked")
    public static void main(String[] args) {
        try (Session session = getSession()) {
            Criteria criteria = session.createCriteria(Track.class)
                    .setProjection(Projections.rowCount());

            List<?> result = criteria.list();
            if (!result.isEmpty()) {
                Long rowCount = (Long) result.get(0);
                System.out.println("Total records: " + rowCount);
            }
        }
    }
}

Maven Dependencies

<dependencies>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>5.6.9.Final</version>
    </dependency>
    <dependency>
        <groupId>com.mysql</groupId>
        <artifactId>mysql-connector-j</artifactId>
        <version>8.0.33</version>
    </dependency>
</dependencies>

Maven Central Maven Central

How do I order the Criteria query result set?

By Wayan in Hibernate 0 Comment

In this demo you’ll see how to order the result set of out Criteria query. It can be done by adding the org.hibernate.criterion.Order into the Criteria object, and we can either order the result in ascending or descending order.

package org.kodejava.hibernate;

import org.hibernate.SessionFactory;
import org.hibernate.Session;
import org.hibernate.HibernateException;
import org.hibernate.Criteria;
import org.hibernate.cfg.Configuration;
import org.hibernate.criterion.Order;
import org.kodejava.hibernate.model.Track;

import java.util.List;

public class CriteriaOrderDemo {
    public static Session getSession() throws HibernateException {
        String cfg = "hibernate.cfg.xml";
        SessionFactory sessionFactory = new Configuration().configure(cfg)
                .buildSessionFactory();
        return sessionFactory.openSession();
    }

    @SuppressWarnings("unchecked")
    public static void main(String[] args) {
        try (Session session = getSession()) {
            Criteria criteria = session.createCriteria(Track.class)
                    .addOrder(Order.asc("title"))
                    .setFirstResult(0)
                    .setMaxResults(10);

            List<Track> tracks = criteria.list();
            for (Track track : tracks) {
                System.out.println("Track = " + track.getTitle());
            }
        }
    }
}

Maven Dependencies

<dependencies>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>5.6.9.Final</version>
    </dependency>
    <dependency>
        <groupId>com.mysql</groupId>
        <artifactId>mysql-connector-j</artifactId>
        <version>8.0.33</version>
    </dependency>
</dependencies>

Maven Central Maven Central

How do I add Restrictions to the Criteria object?

By Wayan in Hibernate 0 Comment

In this example you’ll learn how to add restrictions to the Criteria object. Using restriction we can narrow the result of our query. In the code below we add some restrictions such as Restrictions.eq(), Restrictions.like() and Restrictions.isNotNull().

In Hibernate framework you’ll find a lot of class the use a method chaining. As in the example below you can see that we actually can add an endless restrictions by calling the add() method.

package org.kodejava.hibernate;

import org.hibernate.SessionFactory;
import org.hibernate.Session;
import org.hibernate.HibernateException;
import org.hibernate.Criteria;
import org.hibernate.criterion.Restrictions;
import org.hibernate.cfg.Configuration;
import org.kodejava.hibernate.model.Track;

import java.util.List;

public class RestrictionsDemo {
    public static Session getSession() throws HibernateException {
        String cfg = "hibernate.cfg.xml";
        SessionFactory sessionFactory = new Configuration().configure(cfg)
                .buildSessionFactory();
        return sessionFactory.openSession();
    }

    @SuppressWarnings("unchecked")
    public static void main(String[] args) {
        try (Session session = getSession()) {
            Criteria criteria = session.createCriteria(Track.class)
                    .createAlias("artist", "artist")
                    .createAlias("genre", "genre")
                    .add(Restrictions.eq("title", "Ob-La-Di, Ob-La-Da"))
                    .add(Restrictions.like("artist.name", "%Beatles%"))
                    .add(Restrictions.isNotNull("genre.name"));

            List<Track> tracks = criteria.list();
            for (Track track : tracks) {
                System.out.println("Track = " + track.getTitle() +
                        "; Artist = " + track.getArtist().getName() +
                        "; Genre = " + track.getGenre().getName());
            }
        }
    }
}

Here are some other restrictions that can also be used to narrow our Criteria query result, for a complete restrictions you can see the Restrictions class documentation.

  • Restrictions.ne("title", "Twist and Shout") – Apply a “not equal” constraint to the named property.
  • Restrictions.ilike("title", "Twist%") – A case-insensitive “like”.
  • Restrictions.isNull("title") – Apply an “is null” constraint to the named property.
  • Restrictions.gt("duration", new Integer(200)) – Apply a “greater than” constraint to the named property.
  • Restrictions.between("duration", new Integer(100), new Integer(200)) – Apply a “between” constraint to the named property
  • Restrictions.or(criterionA, criterionB) – Return the disjunction of two expressions.
  • Restrictions.disjuction() – Group expressions together in a single disjunction.

Maven Dependencies

<dependencies>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>5.6.9.Final</version>
    </dependency>
    <dependency>
        <groupId>com.mysql</groupId>
        <artifactId>mysql-connector-j</artifactId>
        <version>8.0.33</version>
    </dependency>
</dependencies>

Maven Central Maven Central

How do I create a pagination using Criteria?

By Wayan in Hibernate 0 Comment

To create a pagination or limit the result set returned by the Criteria query we can use the setFirstResult() and setMaxResults() method. The setFirstResult() method defines the first row to start with and the setMaxResults() method defines the maximum number of records to read. Let’s see the demo below.

package org.kodejava.hibernate;

import org.hibernate.SessionFactory;
import org.hibernate.Session;
import org.hibernate.HibernateException;
import org.hibernate.Criteria;
import org.hibernate.cfg.Configuration;
import org.kodejava.hibernate.model.Track;

import java.util.List;

public class CriteriaPagingDemo {
    public static Session getSession() throws HibernateException {
        String cfg = "hibernate.cfg.xml";
        SessionFactory sessionFactory = new Configuration().configure(cfg)
                .buildSessionFactory();
        return sessionFactory.openSession();
    }

    @SuppressWarnings("unchecked")
    public static void main(String[] args) {
        try (Session session = getSession()) {
            Criteria criteria = session.createCriteria(Track.class);

            // Set the first record index to read from the result set.
            criteria.setFirstResult(0);
            // Set the maximum number of records to read
            criteria.setMaxResults(10);

            List<Track> tracks = criteria.list();
            for (Track track : tracks) {
                System.out.println("Track = " + track.getTitle());
            }
        }
    }
}

Maven Dependencies

<dependencies>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>5.6.9.Final</version>
    </dependency>
    <dependency>
        <groupId>com.mysql</groupId>
        <artifactId>mysql-connector-j</artifactId>
        <version>8.0.33</version>
    </dependency>
</dependencies>

Maven Central Maven Central

How do I create a Criteria object?

By Wayan in Hibernate 0 Comment

This example show you how to create an instance of Hibernate Criteria class. To create a Criteria we call the factory method of the Session object and pass the persistence class as parameter. To execute the Criteria query we simply call the list() method.

package org.kodejava.hibernate;

import org.hibernate.SessionFactory;
import org.hibernate.Session;
import org.hibernate.HibernateException;
import org.hibernate.Criteria;
import org.hibernate.cfg.Configuration;
import org.kodejava.hibernate.model.Track;

import java.util.List;

public class CreateCriteriaDemo {
    public static Session getSession() throws HibernateException {
        String cfg = "hibernate.cfg.xml";
        SessionFactory sessionFactory = new Configuration().configure(cfg)
                .buildSessionFactory();
        return sessionFactory.openSession();
    }

    @SuppressWarnings("unchecked")
    public static void main(String[] args) {
        try (Session session = getSession()) {
            // Create a new Criteria to query for a collection of Tracks.
            // To create an instance of Criteria we call a createCriteria()
            // factory method of the Session object.
            Criteria criteria = session.createCriteria(Track.class);

            // Call the list() method to retrieve a collections of Tracks
            // from the database.
            List<Track> tracks = criteria.list();

            for (Track track : tracks) {
                System.out.println("Title     = " + track.getTitle());
                System.out.println("Artist    = " + track.getArtist().getName());
                System.out.println("Genre     = " + track.getGenre().getName());
                System.out.println("Record    = " + track.getRecord().getTitle());
                System.out.println("Label     = " + track.getRecord().getLabel().getName());
                System.out.println("-----------------------------------");
            }
        }
    }
}

Maven Dependencies

<dependencies>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>5.6.9.Final</version>
    </dependency>
    <dependency>
        <groupId>com.mysql</groupId>
        <artifactId>mysql-connector-j</artifactId>
        <version>8.0.33</version>
    </dependency>
</dependencies>

Maven Central Maven Central

How do I create a message dialog box?

By Wayan in Swing 0 Comment

This example demonstrate how to create a message dialog box using the JOptionPane class methods. In the code below you’ll see the use of JOptionPane.showMessageDialog(), JOptionPane.showInputDialog() and JOptionPane.showConfirmDialog().

package org.kodejava.swing;

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

public class MessageDialogDemo extends JFrame {
    public MessageDialogDemo() throws HeadlessException {
        initialize();
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> new MessageDialogDemo().setVisible(true));
    }

    private void initialize() {
        setSize(500, 500);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        JButton button1 = new JButton("Click Me!");
        button1.addActionListener(e -> {
            // Show a message dialog with a text message
            JOptionPane.showMessageDialog((Component) e.getSource(),
                    "Thank you!");
        });

        JButton button2 = new JButton("What is your name?");
        button2.addActionListener(e -> {
            // Show an input dialog that will ask you to input some texts
            String text = JOptionPane.showInputDialog((Component) e.getSource(),
                    "What is your name?");
            if (text != null && !text.equals("")) {
                JOptionPane.showMessageDialog((Component) e.getSource(),
                        "Hello " + text);
            }
        });

        JButton button3 = new JButton("Close Application");
        button3.addActionListener(e -> {
            // Show a confirmation dialog which will ask to for a YES or NO
            // button.
            int result = JOptionPane.showConfirmDialog((Component) e.getSource(),
                    "Are you sure want to close this application?");
            if (result == JOptionPane.YES_OPTION) {
                System.exit(0);
            } else if (result == JOptionPane.NO_OPTION) {
                // Do nothing, continue to run the application
            }
        });

        setLayout(new FlowLayout(FlowLayout.CENTER));
        getContentPane().add(button1);
        getContentPane().add(button2);
        getContentPane().add(button3);
    }
}
Message Dialog Box with JOptionPane

Message Dialog Box with JOptionPane

How do I execute external command and obtain the result?

By Wayan in Core API, Lang Package 0 Comment

This example demonstrate how to execute an external command from Java and obtain the result of the command. Here we simply execute a Linux ls -al command on the current working directory and display the result.

package org.kodejava.lang;

import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;

public class ProcessResult {
    public static void main(String[] args) {
        try {
            Process process = Runtime.getRuntime().exec("ls -al");

            // Wait for this process to finish or terminated
            process.waitFor();

            // Get process exit value
            int exitValue = process.exitValue();
            System.out.println("exitValue = " + exitValue);

            // Read the result of the ls -al command by reading the
            // process's input stream
            InputStreamReader is = new InputStreamReader(process.getInputStream());
            BufferedReader reader = new BufferedReader(is);
            String line;
            while ((line = reader.readLine()) != null) {
                System.out.println(line);
            }
        } catch (IOException | InterruptedException e) {
            e.printStackTrace();
        }
    }
}

Below is our program result:

exitValue = 0
total 64
drwxr-xr-x  20 wsaryada  staff   680 Aug  7 14:13 .
drwxr-xr-x   4 wsaryada  staff   136 Jun 18 00:33 ..
-rw-r--r--@  1 wsaryada  staff  6148 Jun 29 14:04 .DS_Store
-rw-r--r--   1 wsaryada  staff   267 May 19 20:47 .editorconfig
drwxr-xr-x  16 wsaryada  staff   544 Aug 10 08:34 .git
-rw-r--r--   1 wsaryada  staff  1535 May 19 20:47 .gitignore
drwxr-xr-x  15 wsaryada  staff   510 Aug 10 08:34 .idea
-rw-r--r--   1 wsaryada  staff  1313 May 19 20:47 LICENSE
-rw-r--r--   1 wsaryada  staff   101 May 19 20:47 README.md
drwxr-xr-x   5 wsaryada  staff   170 Jul 28 23:11 kodejava-basic
drwxr-xr-x   6 wsaryada  staff   204 Jun 30 14:22 kodejava-commons
drwxr-xr-x   6 wsaryada  staff   204 Jul 27 15:32 kodejava-lang-package
drwxr-xr-x@  5 wsaryada  staff   170 Jun 16 20:49 kodejava-mail
drwxr-xr-x   6 wsaryada  staff   204 Aug  7 17:22 kodejava-mybatis
drwxr-xr-x   5 wsaryada  staff   170 Jul 20 10:36 kodejava-poi
-rw-r--r--   1 wsaryada  staff   669 Jun  2 14:29 kodejava-project.iml
drwxr-xr-x   7 wsaryada  staff   238 Jun 26 21:52 kodejava-swing
drwxr-xr-x   6 wsaryada  staff   204 Aug  3 15:06 kodejava-util-package
drwxr-xr-x   6 wsaryada  staff   204 Jun 30 15:09 maven-helloworld
-rw-r--r--   1 wsaryada  staff  1622 Aug  7 14:13 pom.xml

How do I get the JFrame of a component?

By Wayan in Swing 0 Comment

This code snippet gives an example on how to get the JFrame of a component. In this example we try to get the JFrame from a button action listener event. To get the JFrame we utilize the SwingUtilities.getRoot() method and this will return the root component of the component tree in out small program below which is a JFrame.

Beside getting the JFrame, in this program we also do small stuff like changing the frame background color by a random color every time a user presses the “Change Frame Color” button.

package org.kodejava.swing;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingUtilities;
import javax.swing.WindowConstants;
import java.awt.Color;
import java.awt.Component;
import java.awt.FlowLayout;
import java.awt.HeadlessException;

public class GetFrameDemo extends JFrame {
    public GetFrameDemo() throws HeadlessException {
        initialize();
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> new GetFrameDemo().setVisible(true));
    }

    private void initialize() {
        this.setSize(500, 500);
        this.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        this.setLayout(new FlowLayout(FlowLayout.CENTER));

        final JLabel rLabel = new JLabel("r: ");
        final JLabel gLabel = new JLabel("g: ");
        final JLabel bLabel = new JLabel("b: ");

        JButton button = new JButton("Change Frame Background Color");
        button.addActionListener(e -> {
            Component component = (Component) e.getSource();

            // Returns the root component for the current component tree
            JFrame frame = (JFrame) SwingUtilities.getRoot(component);

            int r = (int) (Math.random() * 255);
            int g = (int) (Math.random() * 255);
            int b = (int) (Math.random() * 255);

            rLabel.setText("r: " + r);
            gLabel.setText("g: " + g);
            bLabel.setText("b: " + b);

            frame.getContentPane().setBackground(new Color(r, g, b));
        });

        this.getContentPane().add(button);
        this.getContentPane().add(rLabel);
        this.getContentPane().add(gLabel);
        this.getContentPane().add(bLabel);
    }
}
Get Swing Root Component

Get Swing Root Component

How do I disable JFrame close button?

By Wayan in Swing 0 Comment

To disable the close operation on a JFrame, when user click the close icon on the JFrame, we can set the value of the default close operation to WindowConstants.DO_NOTHING_ON_CLOSE.

package org.kodejava.swing;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
import javax.swing.WindowConstants;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.HeadlessException;

public class DisableCloseButtonDemo extends JFrame {
    public DisableCloseButtonDemo() throws HeadlessException {
        initialize();
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> new DisableCloseButtonDemo().setVisible(true));
    }

    private void initialize() {
        // WindowConstants.DO_NOTHING_ON_CLOSE tell JFrame instance to do
        // nothing when a window closing event occurs.
        this.setDefaultCloseOperation(WindowConstants.DO_NOTHING_ON_CLOSE);

        JButton button = new JButton("Close");
        button.addActionListener(e -> System.exit(0));

        this.setLayout(new FlowLayout(FlowLayout.CENTER));
        this.setSize(new Dimension(500, 500));
        this.getContentPane().add(button);
    }
}