In addition to strict ownership, C++ also has the concept of references, which is different from references in Java. Internally, a reference is a pointer which is not allowed to be null or repointed; therefore no copying is involved when passing it to a function.
As a result, a function signature in C++ can explicitly restrict the programmer from passing a null object as a parameter. In Java the programmer must use documentation or annotations to indicate non-null parameters.
Take a look at these two Java functions for computing the volume of a sphere. The first one throws a runtime exception if a null object is passed to it; whereas the second one silently ignores null objects.
This first implementation ...
