The system of static typing is your friend.  Yes, I know arguments for dynamic typing, but that's a different issue.  The point I'm making is that, if you're using a statically typed language, e.g. Java, use the type system to your benefit.  Don't pass around generic objects; create a specific type, instead.  This type can be implemented with the FlyweightPattern, but it has a distinct type.

Contrast this signature

  void assignCustomerToSalesman(Long customerId, Long salesmanId);

versus

  void assignCustomerToSalesman(C''''''ustomerId customerId, S''''''alesmanId salesmanId);

or even:

  void assignCustomerToSalesman(C''''''ustomer customer, S''''''alesman salesman);

or ''even'':

 class Salesman { ...
  void assignCustomer(C''''''ustomerId customerId);

The latter three have no possibility of getting the arguments in the wrong order.

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I've been looking for a name for this, and haven't found one.  I'm proposing SpecificTypingPattern. --GeorgeDinwiddie
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This SoftwareDevelopmentGuideline is related to the NullObject pattern.

See also: CompilerErrorsAreYourFriends, WholeValuePattern, StronglyTypedCollection, StaticTypeSafety