What is the difference between getDefaultInstance() and getInstance() in Session class?

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Gnanam picture Gnanam · Nov 15, 2010 · Viewed 30.4k times · Source

What is the difference between Session.getDefaultInstance(props, authenticator) and getInstance(props, authenticator)? In general, when will you choose one over the other?

I also read Java doc on getDefaultInstance(props, authenticator), but still couldn't able to make out the difference distinctly/clearly.

Hope experts can help me in understanding this better.

UPDATE: Actual reason that triggered to ask this question is: We've used Session.getDefaultInstance() method in some places within our web-based application. Sometimes, it throws java.lang.SecurityException: Access to default session denied, on quick googling, it suggested to use Session.getInstance() method instead. Hence, when one would choose one over the other?

Answer

Codemwnci picture Codemwnci · Nov 16, 2010

If you read the documentation, you will see that

getDefaultInstance Get the default Session object. If a default has not yet been setup, a new Session object is created and installed as the default.

Therefore, if one does not already exist, it call getInstance()

getInstance Get a new Session object.

So, a new session object is created, regardless of whether one already exists.

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