Tips and good practices for Naked Objects development

This document looks at common mistakes made and problems encountered when developing applications using the Naked Objects framework.

• Value objects should not have a set... method as reassigning the variable can have unexpected consequences. To ensure that you don't add a set method (or your IDE doesn't add one for you) make the variable declaration private.
• Ensure that each business object field has both a set... and a get... method and that the base name is the same and the return type matches the paramter type.
• In a get... method for a business object always resolve (using resolve(NakedObject))the reference to that object before returing it. Remember that this is not required in get... methods for value objects and collections, nor should it be used anywhere else.
• In a set... method for a business object always tell the containing object (using objectChanged()) that it contents have change. Remember that this is not required in get... methods for value objects and collections, nor should it be used anywhere else.
• New objects should be created by calling the createInstance method and providing the Class required rather than using Java's new operator. Remember that the returned reference from this method must be cast to the required object's type.
• Any initialisation of a business object - that is giving it a starting value - should be done in the created method rather than in the constructor. Remember that the constructor is called every time an object is retreived from the object store.

• Don't forget to add a serialization idententifier to each naked objects class you create. E.g:

  private static final long serialVersionUID = 1L;

Techniques

• If you need a field for a status or another form of flag where options don't change, i.e. freeform text is not needed, then use a Option field rather than a TextString. This will allow the user to select from a list rather than having remember the possible values and correctly type the required one in.

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