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Groups > comp.lang.java.programmer > #36940

Re: no easy way to do a reverse pointer?

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This type of cross-reference is common in JPA, with its `@OneToMany`, `@ManyToOne`, and `@ManyToMany` relationships. These are modeled as contained collections. 

One to many is something like:

    public class Manager {
      Set<Employee> underlings;
      ...
    }

Many to one is like:

    public class Employee {
      Manager manager;
      ...
    }

Many to many:

    public class Employee {
      Set<Project> projects;
      ...
    }

    public class Project {
      Set<Employee> members;
      ...
    }

It's a pretty standard, long-standing, and well documented approach.

--
Lew

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no easy way to do a reverse pointer? Eric Douglas <e.d.programmer@gmail.com> - 2017-07-07 11:56 -0700
  Re: no easy way to do a reverse pointer? Martin Gregorie <martin@address-in-sig.invalid> - 2017-07-07 19:48 +0000
    Re: no easy way to do a reverse pointer? Eric Douglas <e.d.programmer@gmail.com> - 2017-07-07 13:28 -0700
      Re: no easy way to do a reverse pointer? Martin Gregorie <martin@address-in-sig.invalid> - 2017-07-07 21:47 +0000
      Re: no easy way to do a reverse pointer? Eric Sosman <esosman@comcast-dot-net.invalid> - 2017-07-07 18:06 -0400
        Re: no easy way to do a reverse pointer? lewbloch@gmail.com - 2017-07-14 14:32 -0700

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