In Criteria API, a CriteriaQuery, CriteriaUpdate, or CriteriaDelete object may be modified, either before or after Query or TypedQuery objects have been created and executed from it.

Quick Example

     .........
     CriteriaQuery<Object[]> criteriaQuery = criteriaBuilder.createQuery(Object[].class);
     Root<Employee> root = criteriaQuery.from(Employee.class);

     //Employees name and salary
     criteriaQuery.multiselect(root.get(Employee_.NAME), root.get(Employee_.SALARY));
     List<Object[]> resultList = entityManager.createQuery(criteriaQuery).getResultList();
     resultList.forEach(arr -> System.out.println(Arrays.toString(arr)));

    
     //Employees name and dept
     criteriaQuery.multiselect(root.get(Employee_.NAME), root.get(Employee_.DEPT));
     List<Object[]> resultList2 = entityManager.createQuery(criteriaQuery).getResultList();
     resultList2.forEach(arr -> System.out.println(Arrays.toString(arr)));
     .....

Complete Example

Entity

@Entity
public class Employee {
    @Id
    @GeneratedValue
    private long id;
    private String name;
    private double salary;
    private String dept;
    .............
}

Reusing Query Object

public class ExampleMain {
    private static EntityManagerFactory entityManagerFactory =
            Persistence.createEntityManagerFactory("example-unit");

    public static void main(String[] args) {
        try {
            persistEmployees();
            findEmployees();
            findEmployees2();

        } finally {
            entityManagerFactory.close();
        }
    }

    private static void findEmployees() {
        EntityManager entityManager = entityManagerFactory.createEntityManager();
        CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
        CriteriaQuery<Employee> criteriaQuery = criteriaBuilder.createQuery(Employee.class);
        Root<Employee> root = criteriaQuery.from(Employee.class);
        criteriaQuery.select(root);

        System.out.println("-- All employees --");
        List<Employee> resultList = entityManager.createQuery(criteriaQuery).getResultList();
        resultList.forEach(System.out::println);


        System.out.println("-- All employees from IT dept --");
        criteriaQuery.where(criteriaBuilder.equal(root.get(Employee_.DEPT), "IT"));
        List<Employee> resultList2 = entityManager.createQuery(criteriaQuery).getResultList();
        resultList2.forEach(System.out::println);

        entityManager.close();
    }

    private static void findEmployees2() {
        EntityManager entityManager = entityManagerFactory.createEntityManager();
        CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
        CriteriaQuery<Object[]> criteriaQuery = criteriaBuilder.createQuery(Object[].class);
        Root<Employee> root = criteriaQuery.from(Employee.class);

        System.out.println("-- Employees name and salary --");
        criteriaQuery.multiselect(root.get(Employee_.NAME), root.get(Employee_.SALARY));
        List<Object[]> resultList = entityManager.createQuery(criteriaQuery).getResultList();
        resultList.forEach(arr -> System.out.println(Arrays.toString(arr)));

        System.out.println("-- Employees name and dept --");
        criteriaQuery.multiselect(root.get(Employee_.NAME), root.get(Employee_.DEPT));
        List<Object[]> resultList2 = entityManager.createQuery(criteriaQuery).getResultList();
        resultList2.forEach(arr -> System.out.println(Arrays.toString(arr)));

        entityManager.close();
    }


    public static void persistEmployees() {
        Employee employee1 = Employee.create("Diana", 2000, "IT");
        Employee employee2 = Employee.create("Rose", 3500, "Admin");
        Employee employee3 = Employee.create("Denise", 2500, "Admin");
        Employee employee4 = Employee.create("Mike", 4000, "IT");
        Employee employee5 = Employee.create("Linda", 4500, "Sales");
        EntityManager em = entityManagerFactory.createEntityManager();
        em.getTransaction().begin();
        em.persist(employee1);
        em.persist(employee2);
        em.persist(employee3);
        em.persist(employee4);
        em.persist(employee5);
        em.getTransaction().commit();
        em.close();
    }
}

-- All employees --
Employee{id=1, name='Diana', salary=2000.0, dept='IT'}
Employee{id=2, name='Rose', salary=3500.0, dept='Admin'}
Employee{id=3, name='Denise', salary=2500.0, dept='Admin'}
Employee{id=4, name='Mike', salary=4000.0, dept='IT'}
Employee{id=5, name='Linda', salary=4500.0, dept='Sales'}
-- All employees from IT dept --
Employee{id=1, name='Diana', salary=2000.0, dept='IT'}
Employee{id=4, name='Mike', salary=4000.0, dept='IT'}
-- Employees name and salary --
[Diana, 2000.0]
[Rose, 3500.0]
[Denise, 2500.0]
[Mike, 4000.0]
[Linda, 4500.0]
-- Employees name and dept --
[Diana, IT]
[Rose, Admin]
[Denise, Admin]
[Mike, IT]
[Linda, Sales]

Example Project

Dependencies and Technologies Used:

• h2 1.4.199: H2 Database Engine.
• hibernate-core 5.4.2.Final: Hibernate's core ORM functionality.
  Implements javax.persistence:javax.persistence-api version 2.2
• hibernate-jpamodelgen 5.4.2.Final: Annotation Processor to generate JPA 2 static metamodel classes.
• JDK 1.8
• Maven 3.5.4