Question

I am curious whether packing multiple and/or nested method calls within the same line of code is better for performance and that is why some developers do it, at the cost of making their code less readable.

E.g.

//like
Set<String> jobParamKeySet = jobParams.keySet();
Iterator<String> jobParamItrtr = jobParamKeySet.iterator();

Could be also written as

//dislike    
Iterator<String> jobParamItrtr = jobParams.keySet().iterator();

Personally, I hate the latter because it does multiple evaluations in the same line and is hard for me to read the code. That is why I try to avoid by all means to have more than one evaluation per line of code. I also don’t know that jobParams.keySet() returns a Set and that bugs me.
Another example would be:

//dislike
Bar.processParameter(Foo.getParameter());

vs

//like
Parameter param = Foo.getParameter();
Bar.processParameter(param);

The former makes me noxious and dizzy as I like to consume simple and clean evaluations in every line of code and I just hate it when I see other people’s code written like that.

But are there any (performance) benefits to packing multiple method calls in the same line?

EDIT: Single liners are also more difficult to debug, thanks to @stemm for reminding

Answer 1

Micro optimization is killer. If the code references you are showing are either instance scope (or) method scope, I would go with second approach.

Method scope variables will be eligible for GC as soon as method execution done, so even you declare another variable, it’s ok because scope is limited and the advantage you get will be readable and main-table code.