Thread: methods are checked based on the reference, not the object. why?

Check out the following basic code (assume that dog has a method called bark):

Dog d = new Dog();  
Object o = d;  
 
o.bark();  //  error

But why? Isn't o just a pointer to a memory address which has the dog object? If so, why can't the compiler see that the object has a method called bark? Or, to ask the question another way, why is Java designed to check the object reference to see if the method exists instead of the object itself?

o is a Variable which references an Object.
Objects do not have a method called bark; thus you cant call the bark method on an object variable.

You know that the object is actually a Dog, but your compiler cant know that. Since the compiler doesnt know he wont compile it.