What is java pojo class, java bean, normal class?

Question

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Difference between DTO, VO, POJO, JavaBeans?

Hi please don't say my question is duplicate :-) I saw all questions but didn't understand the exact difference.

Can someone explain what is POJO, Bean, Normal Class in easy language?

score 152 · Accepted Answer · edited Aug 20 '17 at 04:14

152

Normal Class: A Java class
Java Beans:
- All properties private (use getters/setters)
- A public no-argument constructor
- Implements Serializable.
Pojo: Plain Old Java Object 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
- Implement prespecified interface
- Contain prespecified annotations

edited Aug 20 '17 at 04:14

bouvierr

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answered Sep 20 '12 at 18:05

Kumar Vivek Mitra

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I heard except no-argument constructor both pojo and bean are same right ? – Siva Sep 21 '12 at 03:08
java bean, implement Serializable means every time we must implement Serializable manually ? – Siva Sep 21 '12 at 03:27
A public no-argument constructor: I think every class has its own no-argument constructor if am correct, why you specified only for bean only ? sorry if am wrong am fresher. – Siva Sep 21 '12 at 03:29
if you did not specify any constructor for a class then only java will create no-argument constructor implicitly. – pathe.kiran Jan 10 '18 at 16:54
So all normal Java classes are POJOs? – firstpostcommenter Jan 16 '18 at 10:12
1

@firstpostcommenter It might be useful to get a description of what POJO is from the [person who coined the term](https://www.martinfowler.com/bliki/POJO.html). ("encoding business logic into regular java objects rather than using Entity Beans"). In other words, POJO was a name to given to describe "plain old java objects" *in order to* contrast Java beans. POJOs are domain/business objects specific, so not necessarily all Java classes are POJOs – THIS USER NEEDS HELP Apr 12 '18 at 23:15

score 29 · Answer 2 · edited Mar 24 '17 at 07:53

29

POJO stands for Plain Old Java Object, and would be used to describe the same things as a "Normal Class" whereas a JavaBean follows a set of rules. Most commonly Beans use getters and setters to protect their member variables, which are typically set to private and have a no-argument public constructor. Wikipedia has a pretty good rundown of JavaBeans: http://en.wikipedia.org/wiki/JavaBeans

POJO is usually used to describe a class that doesn't need to be a subclass of anything, or implement specific interfaces, or follow a specific pattern.

edited Mar 24 '17 at 07:53

Kasun Siyambalapitiya

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answered Sep 20 '12 at 17:46

simap

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also, JavaBeans should implement the Serializable interface. – simap Sep 20 '12 at 17:51
I didn't during creating a bean in spring. – Asif Mushtaq Aug 15 '18 at 16:11

score 8 · Answer 3 · answered Sep 20 '12 at 17:44

8

POJO = Plain Old Java Object. It has properties, getters and setters for respective properties. It may also override Object.toString() and Object.equals().

Java Beans : See Wiki link.

Normal Class : Any java Class.

answered Sep 20 '12 at 17:44

Nandkumar Tekale

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the only difference between a POJO and Beans is that Beans should implement Serializable interface? – shikher.mishra Jun 02 '18 at 21:05

What is java pojo class, java bean, normal class?

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