java - JPA: store OneToMany-Relationship into a map -

i have problems storing onetomany-relationship map. use jpa/hibernate spring.

this code:

@table(name = "room_member", uniqueconstraints = @uniqueconstraint(             columnnames = { "room", "member" })) public class roommember {     @id     @generatedvalue(strategy = generationtype.table)     private long id;      @manytoone(optional = false)     @joincolumn(name = "room")     private room room;      @manytoone(optional = false)     @joincolumn(name = "member")     private member member;      // getters , setters omitted } 

the class want map:

public room {     @id     @generatedvalue(strategy = generationtype.table)     private long id;      @onetomany(mappedby = "room")     @mapkeyjoincolumn(name = "member")     private map<member, roommember> roommember;      // getters , setters omitted } 

i cant running, because nullpointerexception

org.springframework.beans.factory.beancreationexception: error creating bean name 'entitymanagerfactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/hibernatejpaautoconfiguration.class]: invocation of init method failed; nested exception java.lang.nullpointerexception     @ org.springframework.beans.factory.support.abstractautowirecapablebeanfactory.initializebean(abstractautowirecapablebeanfactory.java:1628)     @ org.springframework.beans.factory.support.abstractautowirecapablebeanfactory.docreatebean(abstractautowirecapablebeanfactory.java:555)     @ org.springframework.beans.factory.support.abstractautowirecapablebeanfactory.createbean(abstractautowirecapablebeanfactory.java:483)     @ org.springframework.beans.factory.support.abstractbeanfactory$1.getobject(abstractbeanfactory.java:306)     @ org.springframework.beans.factory.support.defaultsingletonbeanregistry.getsingleton(defaultsingletonbeanregistry.java:230)     @ org.springframework.beans.factory.support.abstractbeanfactory.dogetbean(abstractbeanfactory.java:302)     @ org.springframework.beans.factory.support.abstractbeanfactory.getbean(abstractbeanfactory.java:197)     @ org.springframework.context.support.abstractapplicationcontext.getbean(abstractapplicationcontext.java:1081)     @ org.springframework.context.support.abstractapplicationcontext.finishbeanfactoryinitialization(abstractapplicationcontext.java:856)     @ org.springframework.context.support.abstractapplicationcontext.__refresh(abstractapplicationcontext.java:542)     @ org.springframework.context.support.abstractapplicationcontext.jrlockandrefresh(abstractapplicationcontext.java)     @ org.springframework.context.support.abstractapplicationcontext.refresh(abstractapplicationcontext.java)     @ org.springframework.boot.context.embedded.embeddedwebapplicationcontext.refresh(embeddedwebapplicationcontext.java:122)     @ org.springframework.boot.springapplication.refresh(springapplication.java:737)     @ org.springframework.boot.springapplication.refreshcontext(springapplication.java:370)     @ org.springframework.boot.springapplication.run(springapplication.java:314)     @ de.swr.eva.eventanwendungapplication.main(eventanwendungapplication.java:40) caused by: java.lang.nullpointerexception: null     @ org.hibernate.envers.configuration.internal.metadata.collectionmetadatagenerator.addvaluetomiddletable(collectionmetadatagenerator.java:567)     @ org.hibernate.envers.configuration.internal.metadata.collectionmetadatagenerator.addindex(collectionmetadatagenerator.java:477)     @ org.hibernate.envers.configuration.internal.metadata.collectionmetadatagenerator.addonetomanyattached(collectionmetadatagenerator.java:212)     @ org.hibernate.envers.configuration.internal.metadata.collectionmetadatagenerator.addcollection(collectionmetadatagenerator.java:157)     @ org.hibernate.envers.configuration.internal.metadata.auditmetadatagenerator.addvalueinsecondpass(auditmetadatagenerator.java:321)     @ org.hibernate.envers.configuration.internal.metadata.auditmetadatagenerator.addvalue(auditmetadatagenerator.java:354)     @ org.hibernate.envers.configuration.internal.metadata.auditmetadatagenerator.addproperties(auditmetadatagenerator.java:374)     @ org.hibernate.envers.configuration.internal.metadata.auditmetadatagenerator.generatesecondpass(auditmetadatagenerator.java:713)     @ org.hibernate.envers.configuration.internal.entitiesconfigurator.configure(entitiesconfigurator.java:108)     @ org.hibernate.envers.boot.internal.enversserviceimpl.doinitialize(enversserviceimpl.java:152)     @ org.hibernate.envers.boot.internal.enversserviceimpl.initialize(enversserviceimpl.java:117)     @ org.hibernate.envers.boot.internal.additionaljaxbmappingproducerimpl.produceadditionalmappings(additionaljaxbmappingproducerimpl.java:99)     @ org.hibernate.boot.model.process.spi.metadatabuildingprocess.complete(metadatabuildingprocess.java:288)     @ org.hibernate.jpa.boot.internal.entitymanagerfactorybuilderimpl.metadata(entitymanagerfactorybuilderimpl.java:848)     @ org.hibernate.jpa.boot.internal.entitymanagerfactorybuilderimpl.build(entitymanagerfactorybuilderimpl.java:875)     @ org.springframework.orm.jpa.vendor.springhibernatejpapersistenceprovider.__createentitymanagerfactory(springhibernatejpapersistenceprovider.java:60)     @ org.springframework.orm.jpa.vendor.springhibernatejpapersistenceprovider.createcontainerentitymanagerfactory(springhibernatejpapersistenceprovider.java)     @ org.springframework.orm.jpa.localcontainerentitymanagerfactorybean.__createnativeentitymanagerfactory(localcontainerentitymanagerfactorybean.java:353)     @ org.springframework.orm.jpa.localcontainerentitymanagerfactorybean.createnativeentitymanagerfactory(localcontainerentitymanagerfactorybean.java)     @ org.springframework.orm.jpa.abstractentitymanagerfactorybean.buildnativeentitymanagerfactory(abstractentitymanagerfactorybean.java:373)     @ org.springframework.orm.jpa.abstractentitymanagerfactorybean.afterpropertiesset(abstractentitymanagerfactorybean.java:362)     @ org.springframework.beans.factory.support.abstractautowirecapablebeanfactory.invokeinitmethods(abstractautowirecapablebeanfactory.java:1687)     @ org.springframework.beans.factory.support.abstractautowirecapablebeanfactory.initializebean(abstractautowirecapablebeanfactory.java:1624) ... 16 common frames omitted 

it works, if use id key:

@onetomany(mappedby = "room") @mapkey(name = "id") private map<string, roommember> roommember; 

but need member map key. ofc build map manually, think should work automatically.

this 1 works expected:

@onetomany(mappedby = "room") private set<roommember> roommember; 

can see failure , give me hint?

best wishes!

wizo