public class CalculatorImpl 
    extends 
      java.rmi.server.UnicastRemoteObject 
    implements Calculator { 
 
    // Implementations must have an 
    //explicit constructor 
    // in order to declare the 
    //RemoteException exception 
    public CalculatorImpl() 
        throws java.rmi.RemoteException { 
        super(); 
    } 
 
    public long add(long a, long b) 
        throws java.rmi.RemoteException { 
        return a + b; 
    } 
 
    public long sub(long a, long b) 
        throws java.rmi.RemoteException { 
        return a - b; 
    } 
 
    public long mul(long a, long b) 
        throws java.rmi.RemoteException { 
        return a * b; 
    } 
 
    public long div(long a, long b) 
        throws java.rmi.RemoteException { 
        return a / b; 
    } 
}