CODEWITHSUNDEEP
javacollections
Igor Konoplyanko
Igor Konoplyanko

Reputation: 9374

java.util.Set, but with custom constraint on field

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?

Upvotes: 2

Views: 67

Answers (2)

gabor.harsanyi
gabor.harsanyi

Reputation: 599

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.

Upvotes: 4

Eran
Eran

Reputation: 393966

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

Upvotes: 2

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