Java Lock variable assignment before use. Why?

Question

In a lot of of the Java source, (for example LinkedBlockingDeque) I see things like this;

final ReentrantLock lock = new ReentrantLock();

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Answer 1

In this piece of code it doesn't matter: both examples work exactly the same. However if the instance variable lock was not final then it could make a difference as the instance variable could be changed during the locked operation: you then want to make sure that you unlock the same lock that you initially locked.

But as lock is final, it doesn't matter: the local variable assignment in your first example is superfluous.