java - When to use Spring prototype scope?

Question

I want to know when should I exactly use the prototype scope in Spring? I have understood that singleton returns the same object instance if the bean is requested for.

Then why should we consider prototype?

Explanations with examples would help a lot to understand the need for it.

Answer 1

To be clear simple definitions:

• Prototype scope = A new object is created each time it is injected/looked up. It will use new SomeBean() each time.

• Singleton scope = The same object is returned each time it is injected/looked up. Here it will instantiate one instance of SomeBean and then return it each time.

Prototype bean is created at the time of usage. So when you would like to have stateful beans there is a strong need sometimes to have prototypes scope or when you don't want to cache any values in beans. Prototype bean can be associated with one session or some call.

Example:

A data access object (DAO) is not typically configured as a prototype, because a typical DAO does not hold any conversational state; it was just easier for this author to reuse the core of the singleton diagram.