Java 8 forEach use cases -

let's have collection strings , want return first 2 characters of each string (or other manipulation...).

in java 8 case can use either map or foreach methods on stream() collection (maybe else not important right now).

personally use map because associate foreach mutating collection , want avoid this. created small test regarding performance not see improvements when using foreach (i understand small tests cannot give reliable results still).

so use-cases 1 should choose foreach?

map better choice this, because you're not trying do strings yet, map them different strings.

foreach designed "final operation." such, doesn't return anything, , mutating some state -- though not of original collection. instance, might use write elements file, having used other constructs (including map) elements.