java.util.Set，但对字段具有自定义约束

Question

I wonder if there is a nice way to have Set on objects, but constrained on custom fields.

For example I need a Set of POJO's:

class MyPojo {
  private String name;
  private Map<Object, Object> stuff;
  //getters, setters, constructor
}

And I want to have a Set where they will be unique by name. I could implement hash and equals based on name property, but then I can't use really equals to compare them.

Is there some nice workaround or maybe Guava/apache commons collection for this?

Answer 1

You can create wrapper objects. It's like a decorator pattern. You wrap your original object with different hash implementations and then wrapped object will be used in the Set.

Answer 2

You can use a HashMap<String,MyPojo> instead of a Set<MyPojo> . This way, each name can appear at most once in the Map .