Classcast mit Hibernate ManyToMany Join-Abfrage

Question

Ich habe zwei Entitäten, Belohnung und Benutzer, die manytomany wie unten in Zusammenhang stehen:

public class Reward { 
    @Id 
    @Column(name="reward_id") 
    private long rewardId; 
    @ManyToMany(mappedBy="favourite") 
    @LazyCollection(LazyCollectionOption.FALSE) 
    private Collection<User> favouriteUsers; 
} 

und den Benutzer:

public class User { 
    @Id 
    @GeneratedValue(strategy=GenerationType.SEQUENCE) 
    @Column(name="user_id") 
    private long userId; 
    @ManyToMany 
    @JoinTable(name="FAVOURITE", joinColumns=@JoinColumn(name="user_id"), inverseJoinColumns=@JoinColumn(name="favourite_id")) 
    @LazyCollection(LazyCollectionOption.FALSE) 
    private Collection<Reward> favourite = new ArrayList<Reward>(); 
} 

Ich versuche zum Abrufen eines Eintrag aus FAVOURITE Tabelle für einen bestimmten user_id und reward_id die folgenden Kriterien:

@NamedQuery(name="Favourite.byUserAndReward", query="from Reward r join r.favouriteUsers u where u.userId = ? and r.rewardId = ?") 

Das Problem ist, wenn ich diese Abfrage und setze das Ergebnis der Abfrage ausführen Reward zu geben, habe ich die folgende Ausnahme erhalten:

java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to com.xxxxxxx.model.Reward 
    at com.xxxxxxx.sevice.RewardService.addFavourite(RewardService.java:26) 
    at com.xxxxxxx.resources.RewardResource.addFavourite(RewardResource.java:36) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:498) 
    at org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory$1.invoke(ResourceMethodInvocationHandlerFactory.java:81) 
    at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher$1.run(AbstractJavaResourceMethodDispatcher.java:144) 
    at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:161) 
    at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$TypeOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:205) 
    at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:99) 
    at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:389) 
    at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:347) 
    at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:102) 
    at org.glassfish.jersey.server.ServerRuntime$2.run(ServerRuntime.java:326) 
    at org.glassfish.jersey.internal.Errors$1.call(Errors.java:271) 
    at org.glassfish.jersey.internal.Errors$1.call(Errors.java:267) 
    at org.glassfish.jersey.internal.Errors.process(Errors.java:315) 
    at org.glassfish.jersey.internal.Errors.process(Errors.java:297) 
    at org.glassfish.jersey.internal.Errors.process(Errors.java:267) 
    at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:317) 
    at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:305) 
    at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1154) 
    at org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:473) 
    at org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:427) 
    at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:388) 
    at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:341) 
    at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:228) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) 
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) 
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) 
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) 
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:478) 
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) 
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80) 
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:624) 
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) 
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) 
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:799) 
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) 
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:861) 
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1455) 
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) 
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) 
    at java.lang.Thread.run(Thread.java:748) 

Das Hibernate Abfrageprotokoll für diese Abfrage ist unter:

Hibernate: select favouriteu0_.favourite_id as favourit2_3_0_, favouriteu0_.user_id as user_id1_3_0_, user1_.user_id as user_id1_2_1_ from FAVOURITE favouriteu0_ inner join USER user1_ on favouriteu0_.user_id=user1_.user_id where favouriteu0_.favourite_id=? 

Ich kann den Fehler nicht herausfinden. Kann mir bitte jemand helfen?

EDIT: Ein Teil, wo ich die Abfrage bin Ausführung ist:

public Reward addFavourite(long userId, Reward favouriteReward) { 
     Object<Reward> rewardObject = new ObjectImpl<Reward>(); 
     long favouriteId = favouriteReward.getRewardId(); 
     // Check if favourited before. 
     // Below is the line that throws the exception. 
     Reward checkReward = rewardObject.getObjectByNamedQueryLongLong("Favourite.byUserAndReward", userId, favouriteId) 
     if (checkReward != null) { 
      return favouriteReward; 
     } 
} 

Answer 1

[Ljava.lang.Object bedeutet, dass Ihre Abfrage zurückgibt Array von Objekten und Sie versuchen, es zu einem Objekt zu werfen.

UPDATE: Da Sie ohne SELECT Klausel abfragen und auch User Beitritt, kehrt Hibernate sowohl die Reward und User Objekte, das ist, warum Sie Object[] bekommen. Ich kann mir zwei Möglichkeiten zum Lösen vorstellen.

1. können Sie das Objekt erwähnen, dass Sie in der SELECT Klausel wie select r from Reward r join r.favouriteUsers u where u.userId = ? and r.rewardId = ?
2. Oder erhalten möchten, können Sie fetch in Ihrer Abfrage wie from Reward r join fetch r.favouriteUsers u where u.userId = ? and r.rewardId = ?