java - Variable Number of Nested For Loops -

i'm making word unscrambler in java. right have program can print rearrangements of 3 letters chosen word 3 or more letters (no repeats). example, if parameter abcd, print this:

[[abc, abd, acb, acd, adb, adc, bac, bad, bca, bcd, bda, bdc, cab, cad, cba, cbd, cda, cdb, dab, dac, dba, dbc, dca, dcb]]

i'm filling 2d array list permutations. right 2d array has 1 array inside of it, contains permutations 3 letters. want 2d array have arrays permuations of 1 letter, 2 letters, 3 letters, , on, stopping @ length of word. problem need variable number of nested loops accomplish this. 3 letter permutations, have 3 nested loops. each 1 cycles through letters in parameter.

public static void printallpermuations(string word) {     int len = word.length();     arraylist<string> lets = new arraylist<string>();     //this array of letters allows easier access     //so don't have keep substringing     (int = 0; < len; i++)     {         lets.add(word.substring(i, + 1));     }      arraylist<arraylist<string>> newwords = new arraylist<arraylist<string>>();     newwords.add(new arraylist<string>());     (int = 0; < len; i++)     {         (int j = 0; j < len; j++)         {             (int k = 0; k < len; k++)             {                 if (i != j && != k && j != k)                 //prevents repeats making sure indices different                 {                     newwords.get(0).add(lets.get(i) + lets.get(j) + lets.get(k));                 }             }         }     }     system.out.println(newwords); } 

i've looked @ other posts , i've heard recursion can solve this. don't know how implement that, though. , i've seen complicated solutions don't understand. i'm asking simplest solution possible, whether involves recursion or not.

with recursive method put 1 of looping in function pass loop parameters function. within function's loop, calls nest loop.

void loopfunction(arraylist<arraylist<string>> newwords, int level) {     if (level == 0) { // terminating condition         if (/* compare indices example passing down list them in  */)         {             newwords.get(...).add(...);         }     } else {// inductive condition         (int = 0; < len; i++) {             loopfunction(newwords, level-1);         }     } } 

so example need 3 levels of recursion start recursion with:

loopfunction(newwords, 3); 

edit

since have been having trouble here working version. keeps list of indices compare against , builds string goes. rearranged words added 2d array @ each level lengths of words. recursion easiest think functionally , not change , keep variables immutable (unchangeable). code although update indices rather create new copy convenience.

void loopfunction(arraylist<string> lets, arraylist<arraylist<string>> newwords, int level, arraylist<integer> indices, string word) {     if (level == 0) { // terminating condition         return;     } else { // inductive condition         (int = 0; < lets.size(); i++) {             if (!indices.contains(i)) { // make sure no index equal                 int nextlevel = level-1;                 string nextword = word+lets.get(i);                  newwords.get(level-1).add(nextword);                  indices.add(i);                 loopfunction(lets, newwords, nextlevel, indices, nextword);                 indices.remove((integer) i);             }         }     } }