arrays - How to create a Systematic List in Java? -

hey guys, i'm trying create systematic list generator in java i've come slight error. our example pizza.

problem: suppose have 6 total toppings make pizzas with. how many variations of 5 topping pizza's can possibly make?

so example :

[pepperoni, bacon, pineapple, onion, mushrooms, peppers] [pepperoni, bacon, pineapple, onion, mushrooms, cheese] etc...

while developing, have been practising 3 possible options apposed 6, know there 3 total combinations each 2 elements, making multi-dimentional array easy generate @ time.

public class systematiclist {  static string options[] = {     "pepperoni",     "bacon",     "cheese" };  public static void main(string[] args) {      /**      * generate multi-dimensional array represent combinations of      * pizza toppings can possibly have available <code>options</code>      *      */     string[][] combos = new string[3][2];      /**      * ideally create.      * combos[0][0] = "pepperoni";      * combos[0][1] = "bacon";      * combos[1][0] = "pepperoni";      * combos[1][1] = "cheese";      * combos[2][0] = "bacon";      * combos[2][1] = "cheese";      */     (int pizzas = 0; pizzas < combos.length; pizzas++) {         (int toppings = 0; toppings < combos[pizzas].length; toppings++) {             combos[pizzas][toppings] = options[0]; // <<< issue : element.             system.out.print(" " + combos[pizzas][toppings]);         }         system.out.println("");     }      /*      * current output :      * run:      *  pepperoni bacon      *  pepperoni bacon      *  pepperoni bacon      * build successful (total time: 0 seconds)      *       * ^ obvious, not know how i'll select      * element array of topping options before/after specified      * index [example: 0 range 1 - 2 apposed 0 - 2      * 'dropping' optional element, making easier.      *      * loop virtually doing actions of :      * 0 : 1,2      * 1 : 1,2      * 2 : 1,2      */ } 

}

i have decided generate 2d list store values.

int[# possible combinations][# possible values]

my current code assumes know possible combinations (though of course not), , regardless can determine values (how many 5, 4, 3, 2 topping pizzas can built)

how able select element options[] while ensuring no other array contains elements you're trying insert. have tried arrays.contains or arrays.equals not know insert compare with, combos[pizzas-1] ?

if (!arrays.contains(combos[pizzas], combos[pizzas-1]) { combos[pizzas][toppings] = options[?]; } 

one way @ toppings haven't considered yet. instance when choosing 3 toppings [pepperoni, bacon, pineapple, onion, mushrooms, peppers, cheese], might decide skip cheese, choose peppers, skip mushrooms , onion, , choose pineapple , bacon. need leave enough toppings finish pizza of course, can't skip cheese, peppers, mushrooms, onion and pineapple. sample code in javascript using recursive algorithm give idea.

function combos(toppings, count) {   var result = [];   helper(result, [], toppings, toppings.length, count);   return result; }  function helper(result, selection, toppings, length, count) {   if (count == 0) // no more toppings left add     result.push(selection); // must solution   else     // start @ --count because need able add other toppings     (var = --count; < length; i++)       // add selected topping selection       // consider toppings haven't looked @ yet       helper(result, selection.concat([toppings[i]]), toppings, i, count); }