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

Question

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

Answer 1

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.