java 实现 快速排序算法 QuickSort

public class QuickSort {
	
	private static Comparable median3(Comparable[] data, int left, int right){
		
		int center = (left + right) / 2;
		if(data[center].compareTo(data[left]) < 0)
			swapReferences(data, left ,center);
		if(data[right].compareTo(data[left]) < 0)
			swapReferences(data, left, right);
		if(data[right].compareTo(data[center]) < 0)
			swapReferences(data, center, right);
		
		swapReferences(data, center, right - 1);
		return data[right - 1];
		
	}
	
	private static void swapReferences(Comparable[] data, int src, int des){
		Comparable tmp;
		tmp = data[des];
		data[des] = data[src];
		data[src] = tmp;
	}
	
	private static void quicksort(Comparable[] data, int left, int right){
		if(left + CUTOFF <= right){
			Comparable pivot = median3(data, left, right);
			
			int i = left,j = right - 1;
			for(;;){
				while(data[++i].compareTo(pivot) < 0){}
				while(data[--j].compareTo(pivot) > 0){}
				if(i < j)
					swapReferences(data, i, j);
				else
					break;
			}
			swapReferences(data, i, right - 1);
			
			quicksort(data, left, i - 1);
			quicksort(data,i + 1, right);
			
		}
		else
			insertionSort(data, left, right);
	}
	
	
	private static void insertionSort(Comparable[] data, int left, int right){
		int j;
		for(int p = left; p <= right; p++){
			Comparable tmp = data[p];
			for(j = p; j > left && tmp.compareTo(data[j-1]) < 0; j--)
				data[j] = data[j-1];
			data[j] = tmp;
				
		}
	}
	
	
	public static void quickSort(Comparable[] data){
		quicksort(data, 0, data.length - 1);
		
	}
	
	public static  void main(String[] args){
		
		Comparable[] a = new Comparable[50];
		for(int i = 0 ; i < a.length; i++)
			a[i] = (int)(Math.random() * 1000);
		for(int i = 0; i < a.length; i++)
			System.out.print(a[i] + " , ");
		
		System.out.println("After: ");
		quickSort(a);
		for(int i = 0; i < a.length; i++)
			System.out.print(a[i] + ", ");
		
	}
	
	private final static int CUTOFF = 10;

}