Any chance of Object auto casting to Integer?

Question

I am wondering whether the below code should work in any scenario?

Object value = attValue.getValue(); // Returns an Object, might contain an Integer
        if (value instanceof Integer) { 
            if (mAccount.getValue() != value) { // mAccount.getValue() return int
               // Do something here
            }
        }

It works in my Android studio but not in some other's PC. What is making it work for me?

Answer 1

Yes, that's entirely feasible given the way autoboxing is guaranteed to work on small values, and is permitted to work on larger values. For example, this is guaranteed to print true:

Object x = 5;
Object y = 5;
System.out.println(x == y);

This might print true, but isn't guaranteed to:

Object x = 10000;
Object y = 10000;
System.out.println(x == y);

I would definitely try not to rely on this in code though, partly because while values in the range of -128 to 127 inclusive are guaranteed to be reused (see JLS 5.1.7), the fact that some JVMs may reuse a wider range of values could lead you into a false sense of security about your code.

In your case, we don't know whether you're seeing a difference in platforms (also bearing in mind that we're talking about Android rather than a JVM) or just that when it "worked" the value being boxed was small, and when it "didn't work" it wasn't.