What is the difference between POJO (Plain Old Java Object) and DTO (Data Transfer Object)?

Question

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

Answer 1

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 They are an outdated concept.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 2

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

Answer 3

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).