If Java were pass by reference...

[marc weber]

I "know" that Java always passes by value, but I want to verify my understanding of what this means. Consider the following code snippet.

...
A a1 = new A();
changer(a1);
 
void changer(A a2) {
  a2 = null;
}
...

In the above code, an instance of A is created and a reference to that instance is assigned to the variable a1. Then a copy of that reference (that is, a value) is passed to the method changer, where it's assigned to a local variable a2. Now, a2 is pointing to the same object as a1, so the actual object can be modified from within the method.

But here's the distinction: When a2 is assigned to null, this has no effect on a1 because the reference originally assigned to a2 was only a copy (a value). On the other hand, if Java were actually pass by reference, then instead of a copy of the reference, a2 would have held the reference itself, and changing it to null would have also changed a1 to a null reference.

Is this accurate?

[Mani Ram]

Originally posted by marc weber:
Is this accurate?

Yes.