Constructor injection has these three distinct advantages over field/setter
injection:
- always thread safe
- fields can be marked final
- you don't have to keep references to objects you need during construction
Kalle
On Sun, Apr 6, 2014 at 1:08 PM, Sanket Sharma <sanketsha...@gmail.com>wrote:
> I battled with the same issue yesterday - injection happens after the
> constructor has run!
>
>
> On Sun, Apr 6, 2014 at 9:26 PM, John <j...@quivinco.com> wrote:
>
> > problem solved, the Logger was of course not yet injected! Duh. I wish
> the
> > IoC stack dump were more helpful.
> >
> > J
> > ----- Original Message -----
> > From: John
> > To: users@tapestry.apache.org
> > Sent: Sunday, April 06, 2014 6:35 PM
> > Subject: NullPointer for service constructor
> >
> >
> > I'm trying to constuct a service implimentation that receives
> references
> > to a couple of other services that registers the objects into a super
> > class. But I get a null pointer exception.
> >
> > What am I doing wrong here?
> >
> >
> > public class AppModule {
> >
> > public static void bind(ServiceBinder binder) {
> > // bind low-level services and utilities
> > binder.bind(CommonsEmailNotificationSender.class); //
> implements
> > NotificationSender to send email
> > binder.bind(TextMarketerNotificationSender.class); //
> implements
> > NotificationSender to send sms
> >
> > ...
> > // bind facades
> > ...
> > binder.bind(NotificationSenderFacade.class,
> > DefaultNotificationSenderFacade.class); // combines the
> NotificationSender
> > instances above
> >
> > }
> >
> >
> >
> > public interface NotificationSender {
> >
> > boolean sendNotification(String toUsername, String fromUsername,
> > String replyto, String to, String messageText, boolean admin);
> >
> > boolean sendNotificationLater(String toUsername, String
> > fromUsername, String replyto, String to, String messageText, boolean
> admin);
> >
> >
> >
> > public interface NotificationSenderFacade {
> >
> > NotificationSender getNotificationSender(String classnme);
> >
> > boolean sendNotification(String toUsername, String fromUsername,
> > List<NotificationRouting>routes, String messageText, boolean admin);
> >
> > boolean sendNotificationLater(String toUsername, String
> > fromUsername, List<NotificationRouting>routes, String messageText,
> boolean
> > admin);
> >
> >
> >
> > public abstract class AbstractNotificationSenderFacade implements
> > NotificationSenderFacade {
> >
> > /**
> > * The log.
> > */
> > @Inject
> > private Logger log;
> >
> > private Map<String, NotificationSender> notificationSenders
> > = new HashMap<String, NotificationSender>();
> >
> > // put the notification senders into a map during subclass
> > construction
> > protected void registerNotificationSender(NotificationSender
> > notificationSender) {
> > String classname =
> notificationSender.getClass().getSimpleName();
> > notificationSenders.put(classname, notificationSender);
> > log.info("registered " + classname);
> > }
> >
> >
> >
> > @EagerLoad
> > public class DefaultNotificationSenderFacade extends
> > AbstractNotificationSenderFacade {
> >
> > /**
> > * The log.
> > */
> > @Inject
> > private Logger log;
> >
> > /**
> > * Create the facade for the given the notification senders.
> > *
> > * @param emailNotificationSender
> > * @param smsNotificationSender
> > */
> > public
> > DefaultNotificationSenderFacade(CommonsEmailNotificationSender
> > emailNotificationSender,
> > TextMarketerNotificationSender smsNotificationSender) {
> > super();
> > super.registerNotificationSender(emailNotificationSender);
> > super.registerNotificationSender(smsNotificationSender);
> > log.debug("registered notification senders");
> > }
> >
> > @Override
> > public boolean sendNotification(String toUsername, String
> > fromUsername, List<NotificationRouting> routes, String messageText,
> boolean
> > admin) {
> > boolean success = true;
> > for (NotificationRouting route : routes) {
> > if (route.getTo().contains("@")) {
> > boolean done =
> > super.getNotificationSender("CommonsEmailNotificationSender")
> > .sendNotification(toUsername, fromUsername,
> > route.getReplyto(), route.getTo(), messageText, admin);
> >
> >
> >
> > AppModule.NotificationSenderFacade Loading class
> > com.quivinco.webapps.tbs.utils.DefaultNotificationSenderFacade.
> > AppModule.NotificationSenderFacade Marking class
> > com.quivinco.webapps.tbs.utils.DefaultNotificationSenderFacade to be
> > (re-)loaded
> > AppModule.NotificationSenderFacade BEGIN Analyzing
> > com.quivinco.webapps.tbs.utils.DefaultNotificationSenderFacade
> > AppModule.NotificationSenderFacade Marking class
> > com.quivinco.webapps.tbs.utils.AbstractNotificationSenderFacade to be
> > (re-)loaded
> > AppModule.NotificationSenderFacade BEGIN Analyzing
> > com.quivinco.webapps.tbs.utils.AbstractNotificationSenderFacade
> > AppModule.NotificationSenderFacade END Analyzing
> > com.quivinco.webapps.tbs.utils.AbstractNotificationSenderFacade
> > AppModule.NotificationSenderFacade END Analyzing
> > com.quivinco.webapps.tbs.utils.DefaultNotificationSenderFacade
> > AppModule.CommonsEmailNotificationSender Creating non-proxied instance
> > of service CommonsEmailNotificationSender
> > AppModule.CommonsEmailNotificationSender Invoking constructor
> > com.quivinco.webapps.tbs.utils.CommonsEmailNotificationSender() (at
> > CommonsEmailNotificationSender.java:23) via
> > com.quivinco.webapps.tbs.services.AppModule.bind(ServiceBinder) (at
> > AppModule.java:75) (for service 'CommonsEmailNotificationSender')
> > AppModule.TextMarketerNotificationSender Creating non-proxied instance
> > of service TextMarketerNotificationSender
> > AppModule.TextMarketerNotificationSender Invoking constructor
> > com.quivinco.webapps.tbs.utils.TextMarketerNotificationSender() (at
> > TextMarketerNotificationSender.java:16) via
> > com.quivinco.webapps.tbs.services.AppModule.bind(ServiceBinder) (at
> > AppModule.java:75) (for service 'TextMarketerNotificationSender')
> > AppModule.NotificationSenderFacade Invoking constructor public
> >
> com.quivinco.webapps.tbs.utils.DefaultNotificationSenderFacade(com.quivinco.webapps.tbs.utils.CommonsEmailNotificationSender,com.quivinco.webapps.tbs.utils.TextMarketerNotificationSender)
> > (for service 'NotificationSenderFacade')
> > ioc.Registry Error invoking constructor public
> >
> com.quivinco.webapps.tbs.utils.DefaultNotificationSenderFacade(com.quivinco.webapps.tbs.utils.CommonsEmailNotificationSender,com.quivinco.webapps.tbs.utils.TextMarketerNotificationSender):
> > java.lang.NullPointerException
> > ioc.Registry Operations trace:
> > ioc.Registry [ 1] Realizing service NotificationSenderFacade
> > ioc.Registry [ 2] Instantiating service NotificationSenderFacade
> > implementation via
> > com.quivinco.webapps.tbs.services.AppModule.bind(ServiceBinder) (at
> > AppModule.java:75)
> > ioc.Registry [ 3] Reloading class
> > com.quivinco.webapps.tbs.utils.DefaultNotificationSenderFacade.
> > ioc.Registry [ 4] Invoking constructor public
> >
> com.quivinco.webapps.tbs.utils.DefaultNotificationSenderFacade(com.quivinco.webapps.tbs.utils.CommonsEmailNotificationSender,com.quivinco.webapps.tbs.utils.TextMarketerNotificationSender)
> > (for service 'NotificationSenderFacade')
> > AppModule.NotificationSenderFacade Construction of service
> > NotificationSenderFacade failed: Error invoking constructor public
> >
> com.quivinco.webapps.tbs.utils.DefaultNotificationSenderFacade(com.quivinco.webapps.tbs.utils.CommonsEmailNotificationSender,com.quivinco.webapps.tbs.utils.TextMarketerNotificationSender):
> > java.lang.NullPointerException
> >
> >
> >
> >
> > ---
> > This email is free from viruses and malware because avast! Antivirus
> > protection is active.
> > http://www.avast.com
> >
> >
> > ---
> > This email is free from viruses and malware because avast! Antivirus
> > protection is active.
> > http://www.avast.com
> >
>
