custom sorting a java array

Question

I have an [] that has some numbers (distances from some point).
I want to create an array of indexes into the first array where the indexes are sorted by the distance.

Answer 1

You're on the right track, but

• You're better off with an Integer array than an int array if you're using a generic Comparator.
• You have to use Arrays.sort instead Collections.sort for sorting an array.

• You have to make the distances variable final if it's referenced in an anonymous inner class.

  final double[] distances=new double[]{3.2, 1.4, 7.3, 2.2, 9.1};
  Integer[] sortedIDXs  = new Integer[]{0,1,2,3,4};
  Arrays.sort(sortedIDXs, new Comparator() {
      public int compare(Integer idx1, Integer idx2) {
          return Double.compare(distances[idx1], distances[idx2]);
      }
  });