RadixSort.java

public class RadixSort {

    @SuppressWarnings("unchecked")
    private static LinkedList<Integer>[] counter = new LinkedList[] {
            new LinkedList<>(), new LinkedList<>(),
            new LinkedList<>(), new LinkedList<>(),
            new LinkedList<>(), new LinkedList<>(),
            new LinkedList<>(), new LinkedList<>(),
            new LinkedList<>(), new LinkedList<>() };

    public static void radixSort(int[] arr) {
        int max = Integer.MIN_VALUE;
        for (int element : arr) {
            if (element > max) {
                max = element;
            }
        }

        final int maxDigit = String.valueOf(max).length();
        radixSort(arr, maxDigit);
    }

    private static void radixSort(int[] arr, int digitCount) {
        int mod = 10;
        int div = 1;

        for (int i = 0; i < digitCount; i++, div *= 10, mod *= 10) {
            for (final int element : arr) {
                final int bucket = element % mod / div;
                counter[bucket].add(element);
            }

            int pos = 0;
            for (final LinkedList<Integer> element : counter) {
                Integer value;
                while ((value = element.poll()) != null) {
                    arr[pos++] = value;
                }
            }
        }
    }
    
}