refactoring sequatial Java code for parallelism

one major advantage of having libraries built for parallelism is easy of programing. programers don't need to completely familiar with parallel programing to use the libraries. they will need some knowledge parallel programing still to know when to use the library. it also helps programers not reinvent the wheel every time they want to do something in parallel.

the only major disadvantage i can see is behind this type of idea is. that program will probably not be as efficient then it could be if the parallelism was built for that program