Coming from C++, if "passing by pointer value" is considered "passing by value", then what is the opposite? Not passing at all? I mean, there's always going to be _some_ kind of value being passed?
The confusion arises because Java doesn't explicitly distinguish between a and &a; if you write "Foo a = new Foo();" in Java, the behaviour is similar to "Foo *a = new Foo();" in C++. So if we ask how "a" is passed, is the "a" we're talking about the reference or the value?
Seems weird to me to say that Java "passes by value" when all objects being passed are actually references to objects.
Technically yes, but since the language doesn't let you talk about references directly, the concept rarely comes up. Like, in theory you could say "a is a reference that refers to a value of type Foo", but people don't actually say that; they just say "a is of type Foo".
> Seems weird to me to say that Java "passes by value" when all objects being passed are actually references to objects.
Indeed, completely agreed.
void f(Foo x); // pass-by-value
void f(Foo* x); // pass-pointer-by-value
void f(Foo& x); // pass-by-reference
The only real difference between the last two is that the last one shouldn't be sent in as null, isn't it? The test in OPs artictle doesn't really make sense either, because you can switch the values using pointers as well.
C++ just forces you to be explicit about this, as others have pointed out.