Re: Unchecked Cast

From:

KDawg44 <KDawg44@gmail.com>

Newsgroups:

comp.lang.java.programmer

Date:

Thu, 29 Nov 2007 13:30:57 -0800 (PST)

Message-ID:

<2a272ad5-f2e8-4378-9370-33428495a076@g30g2000hsb.googlegroups.com>

On Nov 29, 12:48 pm, KDawg44 <KDaw...@gmail.com> wrote:

On Nov 29, 12:42 pm, KDawg44 <KDaw...@gmail.com> wrote:

Hi,

I am getting an error when I compile my app that i hoping someone can
shed some light on. I am working with OpenChord and am getting a
Serialized object. I am trying to cast that to a RegistrationInfo
Object in my program. I did this by:

                try {
                        return
(RegistrationInfo)chord.retrieve(retrieveKey);
                } catch (ServiceException e) {
                        throw new RuntimeException(e);
                }

When I go to compile, I first get this:

Note: PresenceServer.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.

(PresenceServer.java is the class the above code is in).

So I compile with the -Xlint option and I get this:

PresenceServer.java:102: warning: [unchecked] unchecked cast
found : java.util.Set<java.io.Serializable>
required: ClientPackage.RegistrationInfo
                        return
(RegistrationInfo)chord.retrieve(retrieveKey);
                                                               ^
1 warning

What am I doing wrong?

Thanks for any suggestions.

This appears to be just a warning so can I ignore it for the time
being? What causes this?

Thanks.

Okay... so there must be a reason for a warning.... This is now
causing my application to break....

        public RegistrationInfo lookup(String username) {
                StringKey retrieveKey = new StringKey(username);
                try {
                        return (RegistrationInfo)
chord.retrieve(retrieveKey);
                } catch (ServiceException e) {
                        throw new RuntimeException(e);
                }

        }

Exception:
java.lang.ClassCastException: java.util.HashSet
        at ClientPackage.PresenceServer.lookup(PresenceServer.java:
107)
        at ClientPackage.ChatClient.talk(ChatClient.java:47)
        at ClientPackage.SendMessage.run(SendMessage.java:55)
        at java.lang.Thread.run(Thread.java:595)

What is the correct way to cast this object back to the
RegistrationInfo Object?

Thanks.