Java

Java RSS

Interface ... extends ... implements ... (Need help)

•

Join Date: Oct 2006

Posts: 11

Reputation: balgarath is an unknown quantity at this point

Solved Threads: 0

balgarath

Offline

Newbie Poster

Interface ... extends ... implements ... (Need help)

Nov 6th, 2007

Its been years since I've used Java, this one is stumping me...

I implemented my own Observer/Observable interfaces for use with a 2-way RMI setup(I'm sure theres a better name but I don't know it yet).
I have 2 interfaces ToyStore and ToyFactory. ToyStore extends Remote implements Observer, ToyFactory extends Remote implements Observable. I then have a Server class that implements ToyFactory and a Client class that implements ToyStore(I won't post the code for these 2 yet, I don't think its the problem but if need be I can post).

This is what I get when I compile:

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
$ javac -d ./test Client.java Server.java Observable.java Observer.java ToyFactory.java ToyStore.java
ToyFactory.java:7: '{' expected
        extends Remote 
                      ^
ToyStore.java:7: '{' expected
        extends Remote 
                      ^
2 errors
$ javac -d ./test Client.java Server.java Observable.java Observer.java ToyFactory.java ToyStore.java
ToyFactory.java:7: '{' expected
        extends Remote 
                      ^
ToyStore.java:7: '{' expected
        extends Remote 
                      ^
2 errors

Observer.java

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
package toys;
 
public interface Observer
{
    public void update(Observable o);
}
package toys;

public interface Observer
{
    public void update(Observable o);
}

Observable.java

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
package toys;
 
public interface Observable
{
    public void addObserver(String s);
}
package toys;

public interface Observable
{
    public void addObserver(String s);
}

ToyStore.java

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
package toys;
 
import java.rmi.Remote;
import java.rmi.RemoteException;
 
public interface ToyStore 
    extends Remote 
    implements Observer
{
    String sayHi() throws RemoteException;
    public void update(Observable o) throws RemoteException;
}
package toys;

import java.rmi.Remote;
import java.rmi.RemoteException;

public interface ToyStore 
    extends Remote 
    implements Observer
{
    String sayHi() throws RemoteException;
    public void update(Observable o) throws RemoteException;
}

ToyFactory.java

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
package toys;
 
import java.rmi.Remote;
import java.rmi.RemoteException;
 
public interface ToyFactory
    extends Remote 
    implements Observable
{
    String sayHello() throws RemoteException;
    public void addObserver(String s) throws RemoteException;
}
package toys;

import java.rmi.Remote;
import java.rmi.RemoteException;

public interface ToyFactory
    extends Remote 
    implements Observable
{
    String sayHello() throws RemoteException;
    public void addObserver(String s) throws RemoteException;
}

Am I compiling this wrong? Am I allowed to extend and implement in an interface? Does extending Remote block me from Implementing Observer/Observable? Missing semicolon? Let me know if I need to post the other 2 files...Thanks for the help.

•

Join Date: Feb 2006

Posts: 2,356

Reputation: masijade has much to be proud of

Solved Threads: 252

masijade

Offline

Nearly a Posting Maven

Re: Interface ... extends ... implements ... (Need help)

Nov 6th, 2007

An interface cannot implement anything, since an interface is not an implementation. An interface can only extend interfaces (exactly one).

Edit:

PS If you are a David Eddings fan, it is spelled Belgarath not Balgarath. If not, then please ignore.

Last edited by jwenting; Nov 6th, 2007 at 12:49 pm. Reason: PS it's implementation, not implementattion, and you instead of you

Java Programmer and Sun Systems Administrator

----------------------------------------------

Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it.
--Brian Kernighan

•

Join Date: Oct 2006

Posts: 11

Reputation: balgarath is an unknown quantity at this point

Solved Threads: 0

balgarath

Offline

Newbie Poster

Re: Interface ... extends ... implements ... (Need help)

Nov 6th, 2007

Thanks a lot...I didn't really need the Observer/Observable files anyway I can just make ToyFactory and ToyStore require those methods.

David Eddings fan - yes, great books.

I spelled it that way on purpose, used that name in Ultima Online years ago and it kind of stuck.