Java版快速排序

/*
 * 快速排序是最流行的排序算法，本质上通过把一个数组划分为两个子数组，
 * 然后递归地调用自身为每一个子数组进行快速排序来实现。
 *  ArrayIns.java
 * [e-mail]
 */

package linzhanghui.quicksort;

public class ArrayIns {
    private long[] theArray;
    private int nElems;

    public ArrayIns(int max) {
        theArray = new long[max];
        nElems = 0;
    }

    public void insert(long value) {
        theArray[nElems] = value;
        nElems++;
    }

    public void display() {
        System.out.print("A=");
        for(int j=0; j<nElems; j++)
            System.out.print(theArray[j] + " ");
        System.out.println("");
    }

    public void quickSort() {
        recQuickSort(0, nElems-1);
    }

    public void recQuickSort(int left, int right) {
        if(right-left <= 0)
            return;
        else {
            long pivot = theArray[right];

            int partition = partitionIt(left, right, pivot);
            recQuickSort(left, partition-1);
            recQuickSort(partition+1, right);
        }
    }

    public int partitionIt(int left, int right, long pivot) {
        int leftPtr = left-1;
        int rightPtr = right;
        while(true) {
            while( theArray[++leftPtr] < pivot)
                ;
            while(rightPtr > 0 && theArray[--rightPtr] > pivot)
                ;

            if(leftPtr >= rightPtr)
                break;
            else
                swap(leftPtr, rightPtr);
        }
        swap(leftPtr, right);
        return leftPtr;
    }

    public void swap(int dex1, int dex2) {
        long temp = theArray[dex1];
        theArray[dex1] = theArray[dex2];
        theArray[dex2] = temp;
    }
}

/*
 * 程序随机产生16个2位随机数，显示这16个随机数后,对其进行快速排序并输出。
 * [e-mail]
 */
package linzhanghui.quicksort;

public class QuickSortApp {
    public static void main(String[] args) {
        int maxSize = 16;
        ArrayIns arr;
        arr = new ArrayIns(maxSize);

        for(int j=0; j<maxSize; j++) {
            long n = (int)(java.lang.Math.random()*99);
            arr.insert(n);
        }

        arr.display();
        arr.quickSort();
        arr.display();
    }
}