I would like to avoid duplicate entries in ArrayList

Question

I am looking for an object, such as an ArrayList, that will allow me to avoid duplicate entries. For example, it might have a method that calls "contains ()" to validate each record before adding it to an ArrayList.

ArrayList<String> al = new ArrayList<String>();
if(!al.contains("red")){
  al.add("red");
}

Is there something similar?

Answer 1

ArrayLists and lists are not designed to avoid duplicates at all, they are designed as a type of collection that maintains the order of multiple elements. If you want the collection to be more appropriate for the assignment, you need a set:

Set<String> set = new HashSet<String>();

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