What is the difference between POJO (Plain Old Jav

Question

I cannot find difference between them. Does anyone know how to differentiate them?

Answer 1

A POJO can have behavior. The book POJOs in Action details use of POJOS for application development. DTOs are data containers that help transfer data from one layer to another. DTOs aren't supposed to contain any behavior.

Answer 2

I could understand the difference between POJO and DTO from this sentence of DTO's wiki:

DTOs are simple objects that should not contain any business logic but may contain serialization and deserialization mechanisms for transferring data over the wire.

Also, DTO is perfectly visualized and described in detail in Martin Fowler's Catalog of Patterns of Enterprise Application Architecture

Answer 3

POJO = Plain Old Java Object

DTO = Data Transfer Object

-- Edit

Well, this is assuming you don't know what the acronyms mean. A Pojo is just an object that is free from any sort of inheritance chain. A DTO exists in your data model, so probably follows a strict chain relating it to a given entity.

Answer 4

All DTOs are POJOs, but not all POJOs are DTOs. An example of POJO that is not a DTO is a business class that contains state and behavior (business logic).

Answer 5

POJO or "Plain Old Java Object" is a name used to describe "ordinary" Java objects, as opposed to EJBs (originally) or anything considered "heavy" with dependencies on other technologies.

DTO or "Data Transfer Object" is an object for... well... transferring data, usually between your "business" classes and persistence layer. It typically is a behavior-less class much like a C-style struct. They are an outdated concept.

Answer 6

A POJO is just a simple Java object, the acronym is used to emphasize that it really is nothing special.

A DTO is a Data Transfer Object which is used to encapsulate data that is transferred over a connection between layers or subsystems. See the wikipedia article, it's also a Core J2EE pattern (http://www.oracle.com/technetwork/java/transferobject-139757.html).

http://en.wikipedia.org/wiki/Data_transfer_object