Why to declare local variables as final inside methods?

As a human being, we tend to do silly mistakes. By following some good practices, we can avoid some of them. Making local variables as final is one of the good practice to avoid some kind of mistakes. Following points summarize some of the advantages of final local variables.

1. Using final to local variables, method parameters clearly express your intent.

Suppose you had a method like below.

public boolean createEmptyDocument(final String fileName)

Any attempt to reassign a value to a final variable fileName will result in a compiler error. So it guarantees that you are creating empty document with same name.

2. JIT compiler can perform some optimizations on final fields.

3.Declaring local variable as final automatically ensures thread-safety for that field in multi threaded environment.

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