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JPA - @ManyToMany Examples

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;
.............
}
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@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;
.............
}
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@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;
.............
}
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See Also