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Java 为什么我会得到这个递归堆栈溢出错误？

java spring-boot hibernate

Java 为什么我会得到这个递归堆栈溢出错误？,java,spring-boot,hibernate,spring-data-jpa,Java,Spring Boot,Hibernate,Spring Data Jpa,我有两个对象，它们之间有两个多对多的关系。当我尝试填充一个透视表时，它返回一个stackoverflow异常。我尝试的是将FetchType设置为LAZY，甚至在这两个属性中都添加了@JsonIgnore。但问题仍在不断发生 下面我将介绍我的两个模型、控制器功能和异常。非常感谢 用户模型 数据库图 @数据 @实体 @表（name=“users”） 公共类用户{ @身份证 @GeneratedValue（策略=GenerationType.IDENTITY） 私人长id； //..实例变量 @Ma

我有两个对象，它们之间有两个多对多的关系。当我尝试填充一个透视表时，它返回一个stackoverflow异常。我尝试的是将FetchType设置为LAZY，甚至在这两个属性中都添加了@JsonIgnore。但问题仍在不断发生

下面我将介绍我的两个模型、控制器功能和异常。非常感谢

用户模型 数据库图 

@数据
@实体
@表（name=“users”）
公共类用户{
@身份证
@GeneratedValue（策略=GenerationType.IDENTITY）
私人长id；
//..实例变量
@ManyToMany（mappedBy=“members”，fetch=FetchType.LAZY）
私有集合组；
@ManyToMany（mappedBy=“groupJoinRequests”，fetch=FetchType.LAZY）
私有集合请求；
@凌驾
public int hashCode（）{
返回对象。hashCode（id）；}
@凌驾
公共布尔等于（对象obj）{if（this==obj）{return true；}
如果（obj==null | | getClass（）！=obj.getClass（））{return false；}
Long objId=（（用户）obj.id；
return objId==null？false:Objects.equals（id，objId）；}
}
团体

@数据
@实体
@表（name=“groups”）
公共课组{
@身份证
@GeneratedValue（策略=GenerationType.IDENTITY）
私人长id；
//…实例变量
@多个（级联=级联类型.ALL）
@杰索尼奥雷
@JoinTable（name=“users\u group”，
joinColumns={@JoinColumn（name=“groups_id”）}，
inverseJoinColumns={@JoinColumn（name=“members\u id”）}）
私有集合成员；
@多个（级联=级联类型.ALL）
@杰索尼奥雷
@JoinTable（name=“users\u group\u join\u requests”，
joinColumns={@JoinColumn（name=“group\u join\u requests\u id”）}，
inverseJoinColumns={@JoinColumn（name=“user\u id”）}）
私有集合请求；
@凌驾
public int hashCode（）{
返回对象。hashCode（id）；}
@凌驾
公共布尔等于（对象obj）{if（this==obj）{return true；}
如果（obj==null | | getClass（）！=obj.getClass（））{return false；}
Long objId=（（组）obj.id；
return objId==null？false:Objects.equals（id，objId）；}
}
我现在已将其添加到de User类中的@ManyToMany关系中。不幸的是，它并没有起作用，只是附带说明：在这一行中，可选的userData=userRepository.findById（groupId）；我认为您需要将其更改为userId。仍然没有发现问题，但90%与循环依赖有关。我的意思是将这两个方法添加到组和用户类重写公共int hashCode（）{return Objects.hashCode（id）；}重写公共布尔等于（Object obj）{if（this==obj）{return true；}如果（obj==null | | getClass（）！=obj.getClass（））{return false；}Long objId=（（用户）obj）.id；return objId==null？false:Objects.equals（id，objId）；}如果您可以为数据库表提供清晰的表示，以及多对多关系的工作方式，这将非常有用 
@Data
@Entity
@Table(name = "users")
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;

@Column(name = "username")
private String username;

@Column(name = "first_name")
private String firstName;

@Column(name = "last_name")
private String lastName;

@Column(name = "password")
private String password;

@OneToMany(mappedBy = "user", cascade = CascadeType.REMOVE, fetch = FetchType.EAGER)
@JsonIgnore
private Set<Car> cars;

@ManyToMany(cascade = CascadeType.ALL)
@JoinTable
@JsonIgnore
private Set<Group> groups;

@ManyToMany(cascade = CascadeType.ALL)
@JoinTable
@JsonIgnore
private Set<Group> groupJoinRequests;}

@Data
@Entity
@Table(name = "groups")
public class Group {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;

@Column(name = "title")
private String title;

@Column(name = "description")
private String description;

@Column(name = "image_path")
private String imagePath;

@ManyToMany(mappedBy = "groups")
@JsonIgnore
private Set<User> members;

@ManyToMany(mappedBy = "groups")
@JsonIgnore
private Set<User> groupJoinRequests;}

    @PostMapping("/api/groups/{groupId}/requests/{userId}/accept")
public ResponseEntity<List<User>> acceptJoinRequest(@PathVariable("groupId") long groupId, @PathVariable("groupId") long userId) {
    try {
        Optional<Group> groupData = groupRepository.findById(groupId);
        Optional<User> userData = userRepository.findById(groupId);

        if (groupData.isPresent() && userData.isPresent()) {
            Group group = groupData.get();
            User user = userData.get();


            group.getGroupJoinRequests().remove(user);
            group.getMembers().add(user);
            groupRepository.save(group);
            return new ResponseEntity<>(null, HttpStatus.OK);
        } else {
            return new ResponseEntity<>(HttpStatus.NOT_FOUND);
        }
    } catch (Exception e) {
        return new ResponseEntity<>(null, HttpStatus.INTERNAL_SERVER_ERROR);
    }
}

java.lang.StackOverflowError: null
at com.mysql.cj.jdbc.ConnectionImpl.prepareStatement(ConnectionImpl.java:1575) ~[mysql-connector-java-8.0.19.jar:8.0.19]
at com.zaxxer.hikari.pool.ProxyConnection.prepareStatement(ProxyConnection.java:316) ~[HikariCP-3.4.2.jar:na]
at com.zaxxer.hikari.pool.HikariProxyConnection.prepareStatement(HikariProxyConnection.java) ~[HikariCP-3.4.2.jar:na]
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$5.doPrepare(StatementPreparerImpl.java:149) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:176) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.prepareQueryStatement(StatementPreparerImpl.java:151) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.internal.AbstractLoadPlanBasedLoader.prepareQueryStatement(AbstractLoadPlanBasedLoader.java:198) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.internal.AbstractLoadPlanBasedLoader.executeQueryStatement(AbstractLoadPlanBasedLoader.java:162) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.internal.AbstractLoadPlanBasedLoader.executeLoad(AbstractLoadPlanBasedLoader.java:104) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.collection.plan.AbstractLoadPlanBasedCollectionInitializer.initialize(AbstractLoadPlanBasedCollectionInitializer.java:87) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:710) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.event.internal.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:76) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:102) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.internal.SessionImpl.initializeCollection(SessionImpl.java:2153) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection$4.doWork(AbstractPersistentCollection.java:589) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:264) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:585) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:149) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.PersistentSet.hashCode(PersistentSet.java:458) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at com.bram.fun4.careventapp.models.Group.hashCode(Group.java:10) ~[classes/:na]
at java.base/java.util.HashMap.hash(HashMap.java:339) ~[na:na]
at java.base/java.util.HashMap.put(HashMap.java:607) ~[na:na]
at java.base/java.util.HashSet.add(HashSet.java:220) ~[na:na]
at java.base/java.util.AbstractCollection.addAll(AbstractCollection.java:352) ~[na:na]
at org.hibernate.collection.internal.PersistentSet.endRead(PersistentSet.java:355) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollection(CollectionLoadContext.java:239) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollections(CollectionLoadContext.java:224) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollections(CollectionLoadContext.java:198) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.CollectionReferenceInitializerImpl.endLoading(CollectionReferenceInitializerImpl.java:154) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.AbstractRowReader.finishLoadingCollections(AbstractRowReader.java:267) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.AbstractRowReader.finishUp(AbstractRowReader.java:218) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.ResultSetProcessorImpl.extractResults(ResultSetProcessorImpl.java:137) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.internal.AbstractLoadPlanBasedLoader.executeLoad(AbstractLoadPlanBasedLoader.java:105) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.collection.plan.AbstractLoadPlanBasedCollectionInitializer.initialize(AbstractLoadPlanBasedCollectionInitializer.java:87) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:710) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.event.internal.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:76) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:102) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.internal.SessionImpl.initializeCollection(SessionImpl.java:2153) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection$4.doWork(AbstractPersistentCollection.java:589) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:264) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:585) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:149) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.PersistentSet.hashCode(PersistentSet.java:458) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at com.bram.fun4.careventapp.models.User.hashCode(User.java:14) ~[classes/:na]
at java.base/java.util.HashMap.hash(HashMap.java:339) ~[na:na]
at java.base/java.util.HashMap.put(HashMap.java:607) ~[na:na]
at java.base/java.util.HashSet.add(HashSet.java:220) ~[na:na]
at java.base/java.util.AbstractCollection.addAll(AbstractCollection.java:352) ~[na:na]
at org.hibernate.collection.internal.PersistentSet.endRead(PersistentSet.java:355) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollection(CollectionLoadContext.java:239) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollections(CollectionLoadContext.java:224) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollections(CollectionLoadContext.java:198) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.CollectionReferenceInitializerImpl.endLoading(CollectionReferenceInitializerImpl.java:154) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.AbstractRowReader.finishLoadingCollections(AbstractRowReader.java:267) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.AbstractRowReader.finishUp(AbstractRowReader.java:218) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.ResultSetProcessorImpl.extractResults(ResultSetProcessorImpl.java:137) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.internal.AbstractLoadPlanBasedLoader.executeLoad(AbstractLoadPlanBasedLoader.java:105) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.collection.plan.AbstractLoadPlanBasedCollectionInitializer.initialize(AbstractLoadPlanBasedCollectionInitializer.java:87) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:710) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.event.internal.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:76) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:102) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.internal.SessionImpl.initializeCollection(SessionImpl.java:2153) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection$4.doWork(AbstractPersistentCollection.java:589) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:264) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:585) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:149) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.PersistentSet.hashCode(PersistentSet.java:458) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at com.bram.fun4.careventapp.models.Group.hashCode(Group.java:10) ~[classes/:na]
at java.base/java.util.HashMap.hash(HashMap.java:339) ~[na:na]
at java.base/java.util.HashMap.put(HashMap.java:607) ~[na:na]
at java.base/java.util.HashSet.add(HashSet.java:220) ~[na:na]
at java.base/java.util.AbstractCollection.addAll(AbstractCollection.java:352) ~[na:na]
at org.hibernate.collection.internal.PersistentSet.endRead(PersistentSet.java:355) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollection(CollectionLoadContext.java:239) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollections(CollectionLoadContext.java:224) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollections(CollectionLoadContext.java:198) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.CollectionReferenceInitializerImpl.endLoading(CollectionReferenceInitializerImpl.java:154) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.AbstractRowReader.finishLoadingCollections(AbstractRowReader.java:267) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.AbstractRowReader.finishUp(AbstractRowReader.java:218) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.ResultSetProcessorImpl.extractResults(ResultSetProcessorImpl.java:137) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.internal.AbstractLoadPlanBasedLoader.executeLoad(AbstractLoadPlanBasedLoader.java:105) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.collection.plan.AbstractLoadPlanBasedCollectionInitializer.initialize(AbstractLoadPlanBasedCollectionInitializer.java:87) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:710) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.event.internal.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:76) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:102) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.internal.SessionImpl.initializeCollection(SessionImpl.java:2153) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection$4.doWork(AbstractPersistentCollection.java:589) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:264) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:585) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:149) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.PersistentSet.hashCode(PersistentSet.java:458) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at com.bram.fun4.careventapp.models.User.hashCode(User.java:14) ~[classes/:na]
at java.base/java.util.HashMap.hash(HashMap.java:339) ~[na:na]
at java.base/java.util.HashMap.put(HashMap.java:607) ~[na:na]
at java.base/java.util.HashSet.add(HashSet.java:220) ~[na:na]
at java.base/java.util.AbstractCollection.addAll(AbstractCollection.java:352) ~[na:na]
at org.hibernate.collection.internal.PersistentSet.endRead(PersistentSet.java:355) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollection(CollectionLoadContext.java:239) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollections(CollectionLoadContext.java:224) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollections(CollectionLoadContext.java:198) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.CollectionReferenceInitializerImpl.endLoading(CollectionReferenceInitializerImpl.java:154) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.AbstractRowReader.finishLoadingCollections(AbstractRowReader.java:267) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.AbstractRowReader.finishUp(AbstractRowReader.java:218) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.ResultSetProcessorImpl.extractResults(ResultSetProcessorImpl.java:137) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.internal.AbstractLoadPlanBasedLoader.executeLoad(AbstractLoadPlanBasedLoader.java:105) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.collection.plan.AbstractLoadPlanBasedCollectionInitializer.initialize(AbstractLoadPlanBasedCollectionInitializer.java:87) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:710) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.event.internal.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:76) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:102) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.internal.SessionImpl.initializeCollection(SessionImpl.java:2153) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection$4.doWork(AbstractPersistentCollection.java:589) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:264) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:585) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:149) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.PersistentSet.hashCode(PersistentSet.java:458) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at com.bram.fun4.careventapp.models.Group.hashCode(Group.java:10) ~[classes/:na]
at java.base/java.util.HashMap.hash(HashMap.java:339) ~[na:na]
at java.base/java.util.HashMap.put(HashMap.java:607) ~[na:na]
at java.base/java.util.HashSet.add(HashSet.java:220) ~[na:na]
at java.base/java.util.AbstractCollection.addAll(AbstractCollection.java:352) ~[na:na]
at org.hibernate.collection.internal.PersistentSet.endRead(PersistentSet.java:355) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollection(CollectionLoadContext.java:239) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollections(CollectionLoadContext.java:224) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollections(CollectionLoadContext.java:198) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.CollectionReferenceInitializerImpl.endLoading(CollectionReferenceInitializerImpl.java:154) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.AbstractRowReader.finishLoadingCollections(AbstractRowReader.java:267) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.AbstractRowReader.finishUp(AbstractRowReader.java:218) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.ResultSetProcessorImpl.extractResults(ResultSetProcessorImpl.java:137) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.internal.AbstractLoadPlanBasedLoader.executeLoad(AbstractLoadPlanBasedLoader.java:105) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.collection.plan.AbstractLoadPlanBasedCollectionInitializer.initialize(AbstractLoadPlanBasedCollectionInitializer.java:87) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:710) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.event.internal.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:76) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:102) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.internal.SessionImpl.initializeCollection(SessionImpl.java:2153) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection$4.doWork(AbstractPersistentCollection.java:589) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:264) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:585) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:149) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.collection.internal.PersistentSet.hashCode(PersistentSet.java:458) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at com.bram.fun4.careventapp.models.User.hashCode(User.java:14) ~[classes/:na]
at java.base/java.util.HashMap.hash(HashMap.java:339) ~[na:na]
at java.base/java.util.HashMap.put(HashMap.java:607) ~[na:na]
at java.base/java.util.HashSet.add(HashSet.java:220) ~[na:na]
at java.base/java.util.AbstractCollection.addAll(AbstractCollection.java:352) ~[na:na]
at org.hibernate.collection.internal.PersistentSet.endRead(PersistentSet.java:355) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollection(CollectionLoadContext.java:239) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollections(CollectionLoadContext.java:224) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollections(CollectionLoadContext.java:198) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.CollectionReferenceInitializerImpl.endLoading(CollectionReferenceInitializerImpl.java:154) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.AbstractRowReader.finishLoadingCollections(AbstractRowReader.java:267) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.AbstractRowReader.finishUp(AbstractRowReader.java:218) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.process.internal.ResultSetProcessorImpl.extractResults(ResultSetProcessorImpl.java:137) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.plan.exec.internal.AbstractLoadPlanBasedLoader.executeLoad(AbstractLoadPlanBasedLoader.java:105) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.loader.collection.plan.AbstractLoadPlanBasedCollectionInitializer.initialize(AbstractLoadPlanBasedCollectionInitializer.java:87) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:710) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]
at org.hibernate.event.internal.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:76) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]

@Data
@Entity
@Table(name = "users")
public class User {
  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private long id;
  // .... instance variables


  @ManyToMany(mappedBy="members",fetch=FetchType.LAZY)
  private Set<Group> groups;

  @ManyToMany(mappedBy="groupJoinRequests",fetch=FetchType.LAZY)
  private Set<Group> groupJoinRequests;
  @Override 
  public int hashCode() { 
  return Objects.hashCode(id); } 
  @Override 
  public boolean equals(Object obj) { if (this == obj) { return true; } 
  if (obj == null || getClass() != obj.getClass()) { return false; } 
  Long objId = ((User) obj).id; 
  return objId==null? false: Objects.equals(id, objId); }
  }

    @Data
    @Entity
    @Table(name = "groups")
    public class Group {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;

    // ... instance variables
    @ManyToMany(cascade = CascadeType.ALL)
    @JsonIgnore
    @JoinTable(name = "users_group", 
    joinColumns = { @JoinColumn(name = "groups_id") }, 
    inverseJoinColumns = { @JoinColumn(name = "members_id") })
    private Set<User> members;

    @ManyToMany(cascade = CascadeType.ALL)
    @JsonIgnore
    @JoinTable(name = "users_group_join_requests", 
    joinColumns = { @JoinColumn(name = "group_join_requests_id") }, 
    inverseJoinColumns = { @JoinColumn(name = "user_id") })
    private Set<User> groupJoinRequests;

  @Override 
  public int hashCode() { 
  return Objects.hashCode(id); } 
  @Override 
  public boolean equals(Object obj) { if (this == obj) { return true; } 
  if (obj == null || getClass() != obj.getClass()) { return false; } 
  Long objId = ((Group) obj).id; 
  return objId==null? false: Objects.equals(id, objId); }
    }