Use parallelStream foreach to create HashMap, But sometimes value is empty

Question

Java Code Like :

List DbDetails = ... Like 50000 rows records
Map> details = new HashMap();

DbDetails .parallel         


        

Answer 1

HashMap is not thread-safe, so don't use parallel streams with it.

Besides, why do that there, when streams can do it for you?

DbDetails.parallelStream().collect(Collectors.groupingBy(Detail::getId))