Implementations of the Fisher–Yates shuffle algorithm and Quickselect

Test.java

import java.util.ArrayList;
import java.util.Random;
public class Test {
	/*
	 * Implementation of the Fisher–Yates shuffle algorithm with O(N) time complexity
	 */
	public static <T> void shuffle(ArrayList<T> items)
	{
		if(items == null) throw new NullPointerException();
		Random numberGenerator = new Random();
		for(int i = items.size()-1; i > 0; --i)
		{
			numberGenerator.setSeed(System.nanoTime());
			int randomIndex = numberGenerator.nextInt(i+1);
			T temp = items.get(i);
			items.set(i, items.get(randomIndex));
			items.set(randomIndex, temp);
		}
	}
	public static <T extends Comparable<T>> T orderStatistic(ArrayList<T> items, int index)
	{
		if(items == null) throw new NullPointerException();
		if(index < 1 || index > items.size()) throw new IllegalArgumentException();
		shuffle(items);
		return orderStatistic(items, index-1, 0, items.size()-1);
	}
	/*
	 * Implementation of Quickselect with O(N) average time complexity
	 */
	private static <T extends Comparable<T>> T orderStatistic(ArrayList<T> items, int index, int start, int end)
	{
		//SELECTING PIVOT
		int pivotElementIndex = end;
		//PIVOT SELECTED
		//SWAPPING WITH LAST ELEMENT
		T temp = items.get(pivotElementIndex);
		items.set(pivotElementIndex, items.get(end));
		items.set(end, temp);
		//SWAPPED
		//PARTITIONING THE ARRAY
		int counter = start;
		int i;
		for(i = start; i < end && counter < end; ++i)
		{
			int itemIndexLessThanPivot = -1;
			while(counter < end)
			{
				if(items.get(counter).compareTo(items.get(end)) <= 0)
				{
					itemIndexLessThanPivot = counter;
					++counter;
					break;
				}
				++counter;
			}
			if(itemIndexLessThanPivot == -1) break; //there is no such element
			//SWAP THE ELEMETS
			temp = items.get(i);
			items.set(i, items.get(itemIndexLessThanPivot));
			items.set(itemIndexLessThanPivot, temp);
			//ELEMENTS SWAPPED
		}
		//PUTTING THE PIVOT IN PLACE
		temp = items.get(i);
		items.set(i, items.get(end));
		items.set(end, temp);
		//PIVOT PUT IN PLACE
		//ARRAY PARTITIONED
		if(i == index) return items.get(i);
		else if(i < index) return orderStatistic(items, index, i+1, end);
		else return orderStatistic(items, index, start, i-1);
	}
}