I am trying to implement QuickSort in java but Could not get output? -

i trying implement quicksort taking last element pivot. unable produce valid output.

also change needs done in order make randomized? coding in java.

public class quicksortdemo {     public static void quicksort(int a[], int temp[], int left, int right) {         int q, i;          //why u need check  base case         if (left < right) {             q = partition(a, temp, left, right);             quicksort(a, temp, left, q - 1);             quicksort(a, temp, q + 1, right);              (i = 0; < a.length; i++) {                 system.out.println(a[i]);             }         }     }      public static int partition(int a[], int temp[], int left, int right) {         int x, i, j;          x = a[right];         = left - 1;          (j = left; j <= right - 1; j++) {             if (a[j] <= x) {                 = + 1;                 a[i] = a[j];             }         }          a[i + 1] = a[right];         return + 1;     }      public static void main(string s[]) {         int ar[] = {6, 3, 2, 5, 4};         int p[] = new int[ar.length];         quicksort(ar, p, 0, ar.length - 1);     } } //end class quicksortdemo 

outputshown

2  2  4  5  4  2  2  4  4  4  2  2  4  4  4 

as mentioned in comments, there errors in partition method. when implementing quicksort want swap elements in array , not overwrite ones in front. lost.

furthermore, code starts on left , swappes every element less or equal pivot. these unnecessary operations if element in correct part of array.

it better search element greater pivot left. then, search element less pivot right, swap , continue until necessary elements have been swapped.

the standard implementation (that know) this

public static int partition(int a[], int left, int right) {     int pivot, i, j;      pivot = a[right];     = left;     j = right - 1;      {         // search element greater pivot left, remember position         while ( a[i] <= pivot && < right ) i++;          // search element less pivot right, remember positon         while ( a[j] >= pivot && j > left ) j--;          // if elements in wrong part of array => swap         if ( < j ) swap( a, i, j );      // continue until whole (sub)array has been checked         } while ( j > );      // put pivot element @ final position if possible     if ( a[i] > pivot )         swap ( a, i, right );      // return border / position of pivot element         return i; } 

the swap usual

public static void swap(int[] a, int first, int second) {     int temp = a[first];     a[first] = a[second];     a[second] = temp; } 

also note, there no need use temp within code. code declares in signatures never uses it.