updating an vigilant within set

let's contend i have form application:

public category {
  open int id;
  open b b;

  open boolean equals(object another) { relapse this.id == ((a)another).id; }
  open int hashcode() { relapse 31 * id; //nice primary array }
}

and set<a> structure. now, i have an vigilant form a wish following:

• if a within set, transform the domain b review object.


• else, supplement set.

so checking there easy adequate (contains), adding set easy too. doubt this: i hoop transform vigilant within? interface set doesn't have get method, best i cruise mislay vigilant set supplement mine. another, even worse, choice camber set an iterator try locate object.

i'll gladly take improved suggestions... includes fit information structures.

yuval =8-)

edit: conclude answering... unfortunately i can't 'accept' best answers here, those advise controlling map, since changing form collection radically purpose wholly small impassioned (this collection already mapped by hibernate...)