On Tuesday, June 19, 2018 at 12:44:07 AM UTC+2, scl wrote: > > Unless you tell guice that a dependency is optional it will never inject > null. It would fail with an exception if it could not fullfil a dependency. > > So for me the most likely cause of you seeing null is that the instance > you are inspecting is created by calling new, using reflection or by > another DI framework (like CDI or Spring). > > Best strategy to debug this would be to make the field > _bankAccountProvider final. Then create a constructor to pass in the > instance and annotate the constructor with @Inject. > > Now you can place a breakpoint in the constructor. This will show you who > is creating the instance. And if somebody is calling new the compiler may > already tell you before you execute the code. >
…and in case something else than Guice has to create the instance, then you can injectMembers on the instance to have the fields (and methods) injected by Guice; either using a MembersInjector <https://google.github.io/guice/api-docs/4.2/javadoc/com/google/inject/MembersInjector.html> (that you could have @Inject⋅ed into your Provider) or Injector#injectMembers <https://google.github.io/guice/api-docs/4.2/javadoc/com/google/inject/Injector.html#injectMembers-java.lang.Object-> (which implies that you have access to the Injector at that point; the Injector can be @Inject⋅ed too into your provider, but I'd recommend using a MembersInjector instead). > By the way: I would always favour constructor injection over field > injection > - because it makes writing tests simpler (just call the constructor from > your test class) > - an ugly constructor with 5+ arguments smells stronger than 5+ fields > with annotation. And this is good because having that many dependency is > often a sign that a class has too many responsebilities... > +1 see also https://github.com/google/guice/wiki/MinimizeMutability (and other best practices in the wiki) > > Am 18. Juni 2018 17:19:46 MESZ schrieb Adil Quraish <adilq...@gmail.com > <javascript:>>: >> >> I am trying to get Guice to work in a web application deployed on JBoss >> EAP 6.4 When I try to step through the Guice code, I notice that the >> binding is happening. However, when I try to inject the bound object, I >> always get null. The following are the code changes I have done to enable >> Guice - >> >> >> 1) *web.xml* >> >> <listener> >> <listener-class>com.univeris.guice.GuiceConfig</listener-class> >> </listener> >> >> <filter> >> <filter-name>guiceFilter</filter-name> >> <filter-class>com.google.inject.servlet.GuiceFilter</filter-class> >> </filter> >> >> <filter-mapping> >> <filter-name>guiceFilter</filter-name> >> <url-pattern>/*</url-pattern> >> </filter-mapping> >> >> >> 2) *GuiceConfig* >> >> @Singleton >> public class GuiceConfig extends GuiceServletContextListener { >> @Override >> protected Injector getInjector() { >> Injector injector = Guice.createInjector( >> new ServletModule() { >> @Override >> protected void configureServlets() { >> serve("/uif/*").with(UIFInitializeServlet.class); >> serve("/upm/*").with(IDPServlet.class, >> ImmutableMap.of("instance-name","upm")); >> serve("/uiw/*").with(IDPServlet.class, >> ImmutableMap.of("instance-name","uiw")); >> } >> }, >> new MainModule() >> ); >> >> return injector; >> } >> } >> >> >> 3) *MainModule* >> >> public class MainModule extends AbstractModule { >> >> @Override >> protected void configure() { >> install(new BankAccountModule()); >> install(new CoreModule()); >> } >> } >> >> >> 4) *BankAccountModule* >> >> public class BankAccountModule extends AbstractModule { >> @Override >> protected void configure() { >> bind(BankAccountProvider.class).toProvider(BankAccountGuiceProvider.class); >> >> bind(BankAccountService.class).toProvider(BankAccountServiceProvider.class); >> } >> } >> >> >> 5) *BankAccountGuiceProvider* >> >> public class BankAccountGuiceProvider implements >> Provider<BankAccountProvider> { >> @Override >> public BankAccountProvider get() { >> return ProviderLocator.locateProvider(BankAccountProvider.class); >> } >> } >> >> >> 6) *BankAccountServiceUVS* >> >> @Stateless >> @Interceptors(ServiceInterceptor.class) >> public class BankAccountServiceUVS implements BankAccountService { >> >> @Inject >> private BankAccountProvider _bankAccountProvider; >> >> @Override >> public BankAccountCollection getAllBankAccounts(final Integer entityId, >> final String entityType) { >> BankAccountCollection retVal = >> _bankAccountProvider.getAllBankAccounts(entityId, >> return PojoHelper.cloneObject(retVal); >> } >> } >> >> >> The *_bankAccountProvider* is always injected as null. I have been >> pouring through several forums for several days to no avail. Can someone >> point out what I am missing? >> >> -- You received this message because you are subscribed to the Google Groups "google-guice" group. To unsubscribe from this group and stop receiving emails from it, send an email to google-guice+unsubscr...@googlegroups.com. To post to this group, send email to google-guice@googlegroups.com. Visit this group at https://groups.google.com/group/google-guice. To view this discussion on the web visit https://groups.google.com/d/msgid/google-guice/a809fc0a-ccfa-4961-96be-cb3b23235064%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
