It is generally a good idea to restrict access to your variables as much as reasonably possible. For example make things
private instead of
publicand make variables
final if they aren't supposed to change. I believe the same applies to method parameters, but I find actual practice of this to be extremely rare.
For example, no IDEs that I know of offer warnings for finality of method parameters, even though you should be able to tell easily if the parameter can be made final. Even core Java libraries don't make their method parameters final, even though they could; and I find it pretty rare for a 3rd party library to do this either.
Overall the benefits here are certainly relatively low, given that the scope is so small. Does it give enough benefits though to justify as a coding standard?