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

The "better way" is to use collections. Use a List instead of a String[]:

Set> boog = //...
boog.add(Arrays.asList("a", "b", "c"));
boog.add(Arrays.asList("a", "b", "c"));
boog.add(Arrays.asList("a", "b", "d"));

System.out.println(boog.size()); // 2

Edit

If you absolutely needed to use arrays as keys, you could build a transparent wrapper around each key and put that in the map. Some libraries help you with that. For example, here's how you could do a Set using Trove:

Set boog = new TCustomHashSet(new ArrayHashingStrategy());

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

System.out.println(boog.size()); // 2

//...
public class ArrayHashingStrategy extends HashingStrategy {

   public int computeHashCode(Object[] array) {
      return Arrays.hashCode(array);
   }

   public boolean equals(Object[] arr1, Object[] arr2) {
      return Arrays.equals(arr1, arr2);
   }
}