All sub-sets that sum to zero

SetsSumZero.java

/*
Print all subset of a given set which sums up to ZERO 
{8,3,5,1,-4,-8} 
so ans will be : {8,-8} 
{3,5,-8} 
{3,1,-4} 
*/

import java.util.*;

public class SubsetSumZero
{
  private static Stack<Integer> stk;

  public static void printSets(int[] a) {
      stk = new Stack<Integer>();
    	
      Arrays.sort(a);
      printSets(a, 0, 0);
  }

  private static void printSets(int[] a, int hi, int sum) {
      // Check the sum 
      if (sum == 0 && hi > 0){
        // print the set
        System.out.print("( ");
        for (int y : stk){      
          System.out.print(y + " ");
        } 
        System.out.println(" )");
      }

      // Recursion - check for every higher index
      for (int k=hi; k < a.length; k++) {
          int x = a[k];
          stk.push(x);     // add to the stack
          printSets(a, k+1, sum+x);
          stk.pop();        // remove from the stack
              
               
      }
  }
  
  public static void main(String[] args)
  {
    int[] array = {8,3,5,1,-4,-8}; 
    printSets(array);
  }
}


/*Output:

( -8 -4 1 3 8  )
( -8 3 5  )
( -8 8  )
( -4 1 3  )

*/