Storing arrays in Set and avoiding duplicates

Question

HashSet boog = new HashSet();
boog.add(new String[]{\"a\", \"b\", \"c\"});
boog.add(new String[]{\"a\", \"b\", \"c\"});
boog.add(new          


        

Answer 1

hashCode() of arrays uses the default implementation, which doesn't take into account the elements, and you can't change that.

You can use a List instead, with a hashCode() calculated based on the hashcodes of its elements. ArrayList (as most implementations) uses such function.

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Alternatively (but less preferable, unless you are forced somehow to use arrays), you can use a 'special' HashSet where instead of invoking key.hashCode() invoke Arrays.hashCode(array). To implement that extend HashMap and then use Collections.newSetFromMap(map)