Plain old Java object: Difference between revisions

Revision as of 16:07, 30 January 2020

Revision as of 18:20, 11 May 2020

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==Definition==

Ideally speaking, a POJO is a Java object not bound by any restriction other than those forced by the Java Language Specification; i.e. a POJO '''should not''' have to

#Extend prespecified classes, as in<sourcesyntaxhighlight lang="java">public class Foo extends javax.servlet.http.HttpServlet { ...</sourcesyntaxhighlight>

#Implement prespecified interfaces, as in<sourcesyntaxhighlight lang="java">public class Bar implements javax.ejb.EntityBean { ...</sourcesyntaxhighlight>

#Contain prespecified [[Java annotation|annotations]], as in<sourcesyntaxhighlight lang="java">@javax.persistence.Entity public class Baz { ...</sourcesyntaxhighlight>

However, due to technical difficulties and other reasons, many software products or frameworks described as POJO-compliant actually still require the use of prespecified annotations for features such as persistence to work properly.

The idea is that if the object (actually class) were a POJO before any annotations were added, and would return to POJO status if the annotations are removed then it can still be considered a POJO. Then the basic object remains a POJO in that it has no special characteristics (such as an implemented interface) that makes it a "Specialized Java Object" (SJO or (sic) SoJO).