ReferenceToIntegerConversion

DRAFT

Observed

Correction

Here is what's right.

Java is a type-safe language. An object reference is opaque; there is no way to convert it to an integer address.

However, Java allows auto-boxing and auto-unboxing. Which means that Java automatically can e.g., convert an int into an Integer and vice versa. This doesn’t have anything to do with the object’s address, however!

So Integer i = 5; is correct. And given that Object is a supertype of Integer, even Object o = 5; is correct, and Object o = (Object)5; likewise.

Conversely, int i = new Integer(5); is correct, and int i = (int)new Integer(5);' is correct. However, int i = (int)new Object(); is not correct, because Object is not a subtype of Integer and thus new Object() can’t possibly be cast into an Integer object for unboxing into an int.