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JPA - @ManyToMany Examples

[Last Updated: Nov 8, 2025]

JPA JAVA EE 

@Entity
public class EntityA {
    @Id
    @GeneratedValue
    private int myIdA;
    @ManyToMany
    private List<EntityB> entityBList;
    .............
}

@Entity
public class EntityB {
    @Id
    @GeneratedValue
    private int myIdB;
    private String str;
    .............
}
Original Post




@ManyToMany bidirectional example: 

@Entity
public class EntityA {
    @Id
    @GeneratedValue
    private int myIdA;
    @ManyToMany
    private List<EntityB> entityBList;
    private String strA;
    .............
}

@Entity
public class EntityB {
    @Id
    @GeneratedValue
    private int myIdB;
    @ManyToMany
    private List<EntityA> entityAList;
    private String strB;
    .............
}
Original Post




@ManyToMany with Map values: 

@Entity
public class Employee {
    @Id
    @GeneratedValue
    private long id;
    private String name;
    @ManyToMany
    private Map<Date, Task> tasks;
    .............
}

@Entity
public class Task {
    @Id
    @GeneratedValue
    private long id;
    private String name;
    private String description;
    .............
}
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With java.util.Map: 

@Entity
public class Employee {
    @Id
    @GeneratedValue
    private long id;
    private String name;
    @ManyToMany
    private Map<AssignInfo, Task> taskMap;
    .............
}

@Entity
public class AssignInfo {
    @Id
    @GeneratedValue
    private long id;
    private Date startDate;
    private Date endDate;
    .............
}

@Entity
public class Task {
    @Id
    @GeneratedValue
    private long id;
    private String name;
    private String description;
    .............
}
Original Post

See Also