I was told that, I misunderstand effects of `final`. What are the effects of `final` keyword?

Here is short overview of what I think, I know:
> ###Java final modifier (aka aggregation relation)
>
> **primitive variables**: can be set only once. (memory and performance
> gain)<br>
> **objects variables**: may be modified, final applies to object
> reference.<br>
> **fields**: can be set only once.<br>
> **methods**: can't be overridden, hidden.<br>
> **classes**: can't be extended.<br>
> **garbage collection**: will force Java generational garbage collection
> mark-sweep to double sweep.

###Can's and Cant's
 - Can make clone fail (this is both good and bad)
 - Can make immutable primitives aka const
 - Can make blank immutable - initialized at creation aka readonly
 - Can make objects shallowly immutable
 - Can make scope / visibility immutable
 - Can make method invocation overhead smaller (because it does not need virtual table)
 - Can make method arguments used as final (even if thy are not)
 - Can make objects threadsafe (if object is defined as final, it wont make method arguments final)
 - Can make mock tests (not that you could do anything about it - you can say bugs are intended)
 - Can't make friends (mutable with other friends and immutable for rest)
 - Can't make mutable that is changed to be immutable later (but can with factory pattern like fix)
 - Can't make array elements immutable aka deeply immutable
 - Can't make new instances of object (this is both good and bad)
 - Can't make serialization work

There are no alternatives to `final`, but there is wrapper + private and enums.