@Whalo, include the code snippet so people can see.
Java is a C syntax language, so for the most part the syntax is very similar. Like Desfrau said, pointers, pass by reference versus pass by pointer, or value is the main difference.
Scroll down to C++ and Engine source, there are tutorials here: https://wiki.unrealengine.com/Get_Started_with_UE4#C.2B.2B_Gameplay_Programming