Cyclic group generator

Question

I'm trinying to implement an algorithm to search a generator of a cyclic group G:
n is the order of the group G , and Pi is the decomposition of n to prime numbers like n = P1^e1 x P2^e2 ....x Pk^ek
this is the algorithm :

Step 1 : Choose an element g from G
Step 2 : for each i from 1 to k do
Step 2.1 : b <- pow ( g , n / Pi )
Step 2.3 : if b =1 goto step 1
Step 3 : return g

this is my implementation in java , I want to use a goto but it generate an error :

public int getGenerateur(){
    List<Integer> facteur=new ArrayList<Integer>();
    facteur=this.getFacteur(nombre);    

    double b;
    int generateur=0;   

    boolean etape = true;
       while(etape){
        etape = false;
        System.out.println("generateur aleatoire:");
        generateur =(int) (Math.random() * (nombre - 2)) + 2;
        System.out.println(generateur);


            for(int s=0;s<facteur.size();s++){      
                b=Math.pow(generateur,(nombre/facteur.get(s)))%(nombre+1);
                System.out.println("b= "+b);
                if(b==1){
                   etape = true;
                   break;

                }

            }   
     }
     return generateur;

}

Answer 1

if you use an outer loop and a break statement, you should be able to do what you want to do. It would look something like this

   boolean etape = true;
   while(etape){
    etape = false;
    System.out.println("Entrer un generateur :");
    generateur = sc.nextInt();


        for(int s=0;s<facteur.size();s++){      


            b=Math.pow(generateur,(nombre/facteur.get(s)))%(nombre+1);
            System.out.println("b= "+b);
            if(b==1){
               etape = true;
               break;

            }

        }   
 }
 return generateur;