Pizza.java

public final class Pizza {

   // All the combinartion of topings from none to every one
   public static void allCombinations (final int[] data) {
      combinations (data, 0, new int[data.length]);
   }

   public static void combinations (final int[] data, final int i, final int[] choices) {
      if (i==data.length) {
         // For each topping: include (+1) or exclued (-1)
         System.out.println (java.util.Arrays.toString(choices));
      } else {
         choices [i] = +1; // Choose to include topping 'i'
         combinations (data, i+1, choices);
         choices [i] = -1; // Choose to exclude topping 'i'
         combinations (data, i+1, choices);
         choices [i] = 0;  // (Reset; makes no difference)
      }
   }

   // List of toppings on command line: e.g.,
   // pepperoni, mushrooms, anchovies, spinach, feta cheese
   public static void main (final String [] args) {
      final int [] data  = new int [args.length];
      System.out.printf ("Combinations of %s%n",
            java.util.Arrays.toString(args));
      allCombinations (data);
   }
}