How do interfaces have methods of Object class

Question

Hi All,
Please consider the following code snippet.
public interface EmployeeService
    public void createEmployee(Employee emp);
    public Employee findEmployee(String empId);
public class EmployeeServiceImpl implements EmployeeService
    public void createEmployee(Employee emp) { ................. }
    public Employee findEmployee(String empId) { ................. }
}The above is a simple example where I have an employee object with two service methods to create and find an employee.
Now the consider the following
EmployeeService empService = new EmployeeServiceImpl();
Employee emp = empService.findEmployee("1").So the above code helps me in finding an employee.
Now, we know that you can only call those methods that are defined in the interface.
My question is, if I use the empService you would be able to access the methods of the Object class (equals, hashCode, wait etc.)
How does this happen? In the Jave API we know all class by default override the Object class, so how does it work with interfaces?
Thanks in advance for the reply

Answer 1

[JLS 6.4.4 The Members of an Interface Type|http://java.sun.com/docs/books/jls/third_edition/html/names.html#6.4.4] says:
If an interface has no direct superinterfaces, then the interface implicitly declares a public abstract member method m with signature s, return type r, and throws clause t corresponding to each public instance method m with signature s, return type r, and throws clause t declared in Object, unless a method with the same signature, same return type, and a compatible throws clause is explicitly declared by the interface. It is a compile-time error if the interface explicitly declares such a method m in the case where m is declared to be final in Object.
So, in short, those methods exist in interfaces because the JLS says they do.