Java putting all permutations of an Int array into another array without repeats -

there many other questions on stack overflow this, 1 asks different others. want know how take permutations of int array, without repeats, , put them in 2d array. example, input: {1,2,3} output:

{1,2,3} {1,3,2} {2,1,3} {2,3,1} {3,1,2} {3,2,1} 

how can accomplish this? i'd verbal walk through on how this, or better code. question differs this one because linked 1 uses c++ functions accomplish this. use java.

thanks

java object-oriented language , believe useful consider objects problem might contain.

one thing jumps out of problem domain triple-set of integers, why not define object:

public class triad {      private final int[] components;      public triad(int... numbers) {         this.components = numbers;         if (components.length != 3) throw new illegalargumentexception();     }      @override public boolean equals(object ob) {         if (ob == this) return true;                     if (!(ob instanceof triad)) return false;         triad test = (triad) ob;         return arrays.equals(this.components, test.components);     }      @override public int hashcode() {         return arrays.hashcode(this.components);     } } 

note triad defines equals() method , hashcode() method. important couple of reasons. triad value class, i.e. instances of triad represent values rather active. value classes typically:

• should immutable (as have defined triad far, immutable)
• have well-formed equals() , hashcode() methods

the last property above allows instances used without fear java collections framework. let's put collections framework use:

public static void main(string[] args) {      set<triad> triads = new hashset<triad>();      triad inputtriad;      while (true) {         int[] numbers = ... // read in data source         if (numbers == null) break;         inputtriad = new triad(numbers);         triads.add(inputtriad);     }      // after loop has completed, hashset instance triad contain     // input triads.  contract of hashset guarantees there     // no duplicates.     :     : } 

if must have result in int arrays, simple matter iterate through hashset instance , assign component values of each element result arrays.