快速排序越界或循环

问：

我目前正在尝试在 java 中实现快速排序，当我运行程序时，我要么得到数组长度的索引越界，要么得到无限循环，不要问我怎么做。此外，交换本身在工作时是不正确的，所以是的。

public class Quicksort {

   /*
    * Entry method for Quicksort
    */
   public static void quicksort(int[] a) {
      quicksort(a, 0, a.length-1);
   }

   /*
    * Quicksort! 
    * Operates in-place, i.e. it doesn't create a copy.
    */  
   public static void quicksort(int[] a, int from, int to) {
      // Base case: Sorting range is 1 element or empty.
      if(from >= to){
         return;
      }
      // TODO
      else{
         
         
         
         int ipivot = from; // Pivot p
         System.out.println("Pivot p = " + a[ipivot]);
         printArray(a);
         
         // Split the array in two ranges: Left are the elements <=p and right >p.
         // Do this by swapping the elements that don't belong in the given range. 
         // If i and j cross, swapping is finished.
         int i = ipivot+1;
         int j = to;
         while (i<j) {
            // Look for an element <=p right-hand side 
            while(j>= 0 &&a[j]>a[ipivot]){
               j--;
            }
            
            
            // Look for an element >p left-hand side 
            while(i< a.length && a[i]<a[ipivot]){
               i++;
            }
            
            
            // Swap the elements, but only if pointers aren't crossed.
            if (i<j) {
               swap(a, i, j);
            } 
            else {
               break;
            }
 
               
         }
         // The pivot can now be moved to its final position at i.
         // NOTE: Check if pivot needs to be moved BEFORE i.
         int ipivot_final =i;
         System.out.println("swapping " + a[ipivot] +" @"+ipivot+" and " + a[ipivot_final]+" @"+ipivot_final + " (pivot)");
         swap(a, ipivot, ipivot_final);
         
         printArray(a);
         System.out.println();
         
         // Recursion case: Sort left and right range of pivot recursively.
         quicksort(a, from, ipivot_final-1);
         quicksort(a, ipivot_final+1, to);
      }
   }
   /*
    * HELPER METHODS
    */
   public static void printArray(int[] a) {
      for (int i=0; i<a.length; i++) {
         System.out.print(a[i] + ", ");
      }
      System.out.println();
   }

   public static boolean isSorted( int[] array ) {
      for ( int j=0; j<array.length-1; j++ ) {
         if (array[j] > array[j+1])
            return false;      
      }
      return true;
   }

   private static int[] createRandomArray(int size, int minVal, int maxVal) {
      int[] a = new int[size];
      for (int i=0; i<a.length; i++) {
         a[i] = (int) (Math.random()*(maxVal-minVal) + minVal);
      }
      return a;
   }

   private static void swap(int[] a, int i, int j) {
      int tmp = a[i];
      a[i] = a[j];
      a[j] = tmp;
   }
   
   
   /*
    * MAIN
    */

   public static void main(String[] args) {
      final int MINSIZE = 10;
      final int MAXSIZE = 10;
      for (int size = MINSIZE; size <= MAXSIZE; size++) {
         int[] a = createRandomArray(size, 0, size);
         System.out.println("Unsorted array of size "+a.length);
         printArray(a);
         System.out.println("\nRunning Quicksort ...");
         quicksort(a);
         System.out.println("\nSorted array:");
         printArray(a);
         assert isSorted(a) : "Array is not sorted!";
         if (isSorted(a))
            System.out.println("\n\nSuccess!!\n\n");
         else
            System.out.println("\n\nERROR !! Something went wrong.\n\n");
      }
   }

}

我尝试更改条件的顺序以及条件本身