title: LinkedHashSet or ArrayList
body: <p>I wish to</p>
  
  <ol>
  <li>Avoid duplicated item being inserted.</li>
  <li>When I iterate through the collection class, the returned item is same as insertion order.</li>
  </ol>
  
  <p>May I know, what thing I should consider, to choose either ArrayList (explicitly perform contains check before insertion) or LinkedHashSet?</p>
  
  <p>Thanks.</p>