Java overloading and inheritance rules

Question

I\'ve been studying because I have an exam and I don\'t have many problems with most of Java but I stumbled upon a rule I can\'t explain. Here\'s a code fragment:

Answer 1

The behavior of these method calls is dictated and described by the Java Language Specification (reference section 8.4.9).

When a method is invoked (§15.12), the number of actual arguments (and any explicit type arguments) and the compile-time types of the arguments are used, at compile time, to determine the signature of the method that will be invoked (§15.12.2). If the method that is to be invoked is an instance method, the actual method to be invoked will be determined at run time, using dynamic method lookup (§15.12.4).

In your example, the Java compiler determines the closest match on the compile type of the instance you are invoking your method on. In this case:

A.method(AX)

The closest method is from type A, with signature A.method(A). At runtime, dynamic dispatch is performed on the actual type of A (which is an instance of AX), and hence this is the method that is actually called:

AX.method(A)