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POJava - Permutation of ArrayList elements (Integer) - Can't get it to work properly
 

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    <p>I've been looking around quite a bit to solve my issue. I got many problems solved but this one is still haunting me :S It's been a long time I haven't touch Java programming (programming in general) so be understanding out there! ;)</p> <p>My goal is to get all the combination possible out of an array of integers. When I use the following code, applied to the test array of integer {1, 2, 3, 4}, I expect to have: <br>1 2 3 4 <br>1 2 4 3 <br>1 3 2 4 <br>1 3 4 2 <br>2 1 3 4 <br>2 1 4 3 <br>(...) <br>but here is what I get <br>1 2 3 4 <br>1 2 3 4 4 3 <br>1 2 3 4 4 3 3 2 4</p> <p>Does anybody have a clue, a suggestion or even a solution? Thanks in advance!</p> <pre><code>public class Calculation{ (...) public void Permute(ArrayList&lt;Integer&gt; soFar,ArrayList&lt;Integer&gt; rest){ if(rest.isEmpty()) this.fillMatrice(convertIntegers(soFar)); // there it goes in a previously created arrow of int else{ for(int k=0;k&lt;rest.size();k++){ ArrayList&lt;Integer&gt; next=new ArrayList&lt;Integer&gt;(); next=soFar; next.add(rest.get(k)); ArrayList&lt;Integer&gt; remaining=new ArrayList&lt;Integer&gt;(); List&lt;Integer&gt; sublist = rest.subList(0, k); for(int a=0;a&lt;sublist.size();a++) remaining.add(sublist.get(a)); sublist = rest.subList(k+1,rest.size()); for(int a=0;a&lt;sublist.size();a++) remaining.add(sublist.get(a)); Permute(next,remaining); } } } public static ArrayList&lt;Integer&gt; convertArray(int[] integers){ ArrayList&lt;Integer&gt; convArray=new ArrayList&lt;Integer&gt;(); for(int i=0;i&lt;integers.length;i++) convArray.add(integers[i]); return convArray; } public static int[] convertIntegers(List&lt;Integer&gt; integers){ int[] ret = new int[integers.size()]; for(int i=0;i&lt;ret.length;i++) ret[i]=integers.get(i).intValue(); return ret; } public Calculation() { (...) ArrayList&lt;Integer&gt; soFar=new ArrayList&lt;Integer&gt;(); int[] test={1,2,3,4}; Permute(soFar,convertArray(test)); } </code></pre>
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