Java rarrange enum array

Question

i was wondering how can i reorder enum so that all goats are at the beginning and all sheep are at the end of the array. Right now it actually does the trick but until the arra

Answer 1

If you want to have maximum performance for such a special case you may simply count the number of one of the two possible values and overwrite the array accordingly to get the result that sorting would create:

public static void reorder (Animal[] animals) {
    assert Animal.values().length==2;
    int numGoat=0;
    for(Animal a:animals) if(a==Animal.goat) numGoat++;
    Arrays.fill(animals, 0, numGoat, Animal.goat);
    Arrays.fill(animals, numGoat, animals.length, Animal.sheep);

}

You can see it as a modified version of counting sort.