Java Generics: Require generic to be subclass of a certain type

Question

I have an abstract generic class:

public abstract class AbstractMessageHandler<T extends AbstractMessageHandler>
{
    public abstract List<String> getTypesOfMessages();
    public abstract void handleMessage(String message, CometClient client);

    public T setResponseValues(AbstractMessage request, T response )
    {
        response.setCompanyId(request.getCompanyId());
        response.setMessageGroup(request.getMessageGroup());
        response.setUserId(request.getUserId());
        response.setTimeStamp(AbstractMessage.getCurrentTimeStamp());

        return response;
    }
}

I need the generic subclass to be a subclass of this class. In otherwords, the generic must be a subclass of AbstractMessageHandler. This however gives me compilation issues. Can anyone let me know what I am doing wrong?

Thanks

Answer 1

You need to follow the example of the Enum class:

public abstract class AbstractMessageHandler<T extends AbstractMessageHandler<T>>