JAVA EXAMPLE PROGRAMS

JAVA EXAMPLE PROGRAMS

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Hibernate Eager vs Lazy Fetch Type


The relationships are defined through joins in database. Hibernate represents joins in the form of associations like One-to-One, One-to-Many and Many-to-One. It is required to define Fetch Type when you use any of these associations. Fetch Type decides on whether or not to load all the data belongs to associations as soon as you fetch data from parent table. Fetch type supports two types of loading: Lazy and Eager. By default, Fetch type would be Lazy.

FetchType.LAZY: It fetches the child entities lazily, that is, at the time of fetching parent entity it just fetches proxy (created by cglib or any other utility) of the child entities and when you access any property of child entity then it is actually fetched by hibernate.

FetchType.EAGER: it fetches the child entities along with parent.

Lazy initialization improves performance by avoiding unnecessary computation and reduce memory requirements.

Eager initialization takes more memory consumption and processing speed is slow.

Having said that, depends on the situation either one of these initialization can be used.

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Hibernate Examples

  1. Hibernate hello world (initial setup) example.
  2. What is hibernate.cfg.xml configuration?
  3. What are the basic hibernate persistent annotations?
  4. What is SessionFactory in Hibernate?
  5. What is Session object in Hibernate?
  6. List Hibernate Session interface methods.
  7. What is Hibernate Query object?
  8. Basic Hibernate CRUD operations example.
  9. Hibernate Bidirectional One-to-One mapping using @OneToOne annotation.
  10. Hibernate Unidirectional One-to-One mapping using @OneToOne annotation.
  11. Hibernate Eager vs Lazy Fetch Type
  12. Hibernate Unidirectional One-to-Many mapping using @OneToMany annotation.
  13. Hibernate Bidirectional One-to-Many mapping using @OneToMany annotation.
  14. Hibernate Many-to-Many mapping example using @ManyToMany annotation.
  15. How to enable logging (log4j) in Hibernate?
Knowledge Centre
When to use LinkedList or ArrayList?
Accessing elements are faster with ArrayList, because it is index based. But accessing is difficult with LinkedList. It is slow access. This is to access any element, you need to navigate through the elements one by one. But insertion and deletion is much faster with LinkedList, because if you know the node, just change the pointers before or after nodes. Insertion and deletion is slow with ArrayList, this is because, during these operations ArrayList need to adjust the indexes according to deletion or insetion if you are performing on middle indexes. Means, an ArrayList having 10 elements, if you are inserting at index 5, then you need to shift the indexes above 5 to one more.
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About Author

I'm Nataraja Gootooru, programmer by profession and passionate about technologies. All examples given here are as simple as possible to help beginners. The source code is compiled and tested in my dev environment.

If you come across any mistakes or bugs, please email me to [email protected].

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Reference: Java™ Platform Standard Ed. 7 - API Specification | Java™ Platform Standard Ed. 8 - API Specification | Java is registered trademark of Oracle.
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