Java Array sort: Quick way to get a sorted list of indices of an array

Simple solution to create an indexer array: sort the indexer comparing the data values:

final Integer[] idx = { 0, 1, 2, 3 };
final float[] data = { 1.7f, -0.3f,  2.1f,  0.5f };

Arrays.sort(idx, new Comparator<Integer>() {
    @Override public int compare(final Integer o1, final Integer o2) {
        return Float.compare(data[o1], data[o2]);
    }
});