Let's consider the following example.
public interface SimpleInterface {
public void simpleMethod();
}
public class SimpleClass implements SimpleInterface{
public static void main(String[] args) {
SimpleInterface iRef = new SimpleClass();
SimpleClass cRef = new SimpleClass();
iRef.simpleMethod(); // Allowed. Calling methods defined in interface via interface reference.
cRef.specificMethod(); // Allowed. Calling class specific method via class reference.
iRef.specificMethod(); // Not allowed. Calling class specific method via interface reference.
iRef.notify(); // Allowed????
}
public void specificMethod(){}
@Override
public void simpleMethod() {}
}
I thought, in Java using interface reference we may access only methods that are defined in this interface. But, it seems that it is allowed to access method of class Object via any interface reference. My concrete class "SimpleClass" inherits all the methods that class Object has and definitely the class Object doesn't implement any interface (one would assume that Object implements some interface with methods like notify, wait and etc.). My question is, why it is allowed to access methods of the class Object via interface reference, taking into consideration that other methods in my concrete class are not allowed?
