Can you implement a method to act as a +... but for objects instead of primitives?

Can you implement a method to act as a +... but for objects instead of
primitives?

I think that there is something like this in C/C++, but what about in
java? Can I add a method that will add two of them together, but instead
of doing say obj1.add(obj2) you can do obj1 + obj2? Can you do the same
for -, *, /, and == & other comparatives? Can you create a primitive, or
would that take modifying the JVM?