Working with Logical Methods in Hibernate Criteria Query (HCQ)

Introduction

We will discuss different criteria which can be added to make a successful query in different conditions.

Let’s discuss simple examples to start understanding this.

I am assuming that you have read my older post so I am not rewriting the hibernate configuration file, utility class.

There is some change in course class. Below are the records which are within this table.

We make a class Course and we will perform operation on this class using the Hibernate Criteria Query.

Listing 1: Course class

package model;

import java.io.Serializable;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

/**
 *
 * @author Anurag
 */
@Entity
public class Course implements Serializable {

    @Id
    @GeneratedValue
    @Column(name = "C_ID")
    private Long id;
    private String name;
    private int duration;
    private int rating;

    public Course() {
    }

    public Course(String n, int dur, int r) {
        name = n;
        duration = dur;
        rating = r;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public int getRating() {
        return rating;
    }

    public void setRating(int rating) {
        this.rating = rating;
    }

    public int getDuration() {
        return duration;
    }

    public void setDuration(int duration) {
        this.duration = duration;
    }

    public String getName() {
        return name;
    }

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

We defined a class Course with fields like id, name, duration,rating.
We define the setter and getter function for these
We set the id to be auto generated and also we set the name for this column to be C_ID

Now we make the main class which will use the hibernate criteria query.

and method usage

Listing 2: App2 class (and method)

package Main;
	
/**
 *
 * @author Anurag
 */
import java.util.Iterator;
import java.util.List;
import model.Course;
import org.hibernate.Criteria;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.criterion.Expression;

public class App2 {

    public static void main(String args[]) {

        SessionFactory sf = Utility.getSessionFactory();
        Session s = sf.getCurrentSession();

        Transaction tx = s.beginTransaction();
        Criteria crit = s.createCriteria(Course.class);
        crit.add(Expression.and(Expression.gt("duration", 6), Expression.lt("duration", 12)));
        List course = crit.list();
        for (Iterator it = course.iterator(); it.hasNext();) {
            Course c = (Course) it.next();
            System.out.println("ID: " + c.getId());
            System.out.println("Name: " + c.getName());
            System.out.println("Duration: " + c.getDuration());
        }
        tx.commit();
    }
}

and method take 2 argument which is (method1,method2)
method1 define the starting condition and method2 define the secondary condition. Both condition must be true and then result are shown
We make criteria for the field duration

Figure 1: App2 class (and method)

or method usage

Listing 3: App2 class (or method)

package Main;
	
/**
 *
 * @author Anurag
 */
import java.util.Iterator;
import java.util.List;
import model.Course;
import org.hibernate.Criteria;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.criterion.Expression;

public class App2 {

    public static void main(String args[]) {

        SessionFactory sf = Utility.getSessionFactory();
        Session s = sf.getCurrentSession();

        Transaction tx = s.beginTransaction();
        Criteria crit = s.createCriteria(Course.class);
        crit.add(Expression.or(Expression.gt("duration", 6), Expression.lt("duration", 12)));
        List course = crit.list();
        for (Iterator it = course.iterator(); it.hasNext();) {
            Course c = (Course) it.next();
            System.out.println("ID: " + c.getId());
            System.out.println("Name: " + c.getName());
            System.out.println("Duration: " + c.getDuration());
        }
        tx.commit();
    }
}

or method take 2 argument which is (method1,method2)
method1 define the starting condition and method2 define the secondary condition. Any one condition must be true and then result are shown
We make criteria for the field duration

Figure 2: Method usage

not method usage

Listing 4: App2 class (not method)

package Main;
	
/**
 *
 * @author Anurag
 */
import java.util.Iterator;
import java.util.List;
import model.Course;
import org.hibernate.Criteria;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.criterion.Expression;

public class App2 {

    public static void main(String args[]) {

        SessionFactory sf = Utility.getSessionFactory();
        Session s = sf.getCurrentSession();

        Transaction tx = s.beginTransaction();
        Criteria crit = s.createCriteria(Course.class);
        crit.add(Expression.not(Expression.ge("id",2l)));
        List course = crit.list();
        for (Iterator it = course.iterator(); it.hasNext();) {
            Course c = (Course) it.next();
            System.out.println("ID: " + c.getId());
            System.out.println("Name: " + c.getName());
            System.out.println("Duration: " + c.getDuration());
        }
        tx.commit();
    }
}

not method take 1 argument which is (method1)
method1 define the condition and negate that condition and then show result
We make criteria for the field duration

Figure 3: not method usage

After knowing the above logical methods, you must also know the below most used method. This can be used to check if two values are equal or not.

Equal method usage

Listing 5: App2 class (equal method)

package Main;

/**
 *
 * @author Anurag
 */
import java.util.Iterator;
import java.util.List;
import model.Course;
import org.hibernate.Criteria;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.criterion.Expression;

public class App2 {

    public static void main(String args[]) {

        SessionFactory sf = Utility.getSessionFactory();
        Session s = sf.getCurrentSession();

        Transaction tx = s.beginTransaction();
        Criteria crit = s.createCriteria(Course.class);
        crit.add(Expression.eq("duration", 12));

        List course = crit.list();
        for (Iterator it = course.iterator(); it.hasNext();) {
            Course c = (Course) it.next();
            System.out.println("ID: " + c.getId());
            System.out.println("Name: " + c.getName());
            System.out.println("Duration: " + c.getDuration());
        }
        tx.commit();
    }
}

equal method take 2 argument which is (field name,from,to)
We make criteria for the field duration
We select all those records in which the duration is equal to 12

Figure 4: Equal method usage

We will discuss some more methods in next coming articles. Hope you enjoyed this article. See you next time.