my program loop in the do while

I am trying t learn Java and trying to do small program but i have a little problem with this one cause i am stuck in the do while loop when i choose the answer "N" can you please help me out

package calculatrice;

import java.util.Scanner;

public class Main {



    public static void main(String[] args) {

    Calculatrice fonction =new Calculatrice();
    Scanner sr = new Scanner(System.in);
    boolean noury= true;
    boolean Sonia= true;
    String expression = sr.nextLine();

    while(noury)
    {
        if(expression.contains("+"))
        {

            float x = Float.parseFloat(expression.split("\+")[0]);
            float y = Float.parseFloat(expression.split("\+")[1]);
            float c = fonction.somme(x, y);
            System.out.println("le resultat " + c);

        }

    if(expression.contains("-"))
        {

            float x = Float.parseFloat(expression.split("\-")[0]);
            float y = Float.parseFloat(expression.split("\-")[1]);
            float c = fonction.soustraction(x, y);
            System.out.println("le resultat " + c);

        }

    if(expression.contains("*"))
        {

            float x = Float.parseFloat(expression.split("\*")[0]);
            float y = Float.parseFloat(expression.split("\*")[1]);
            float c = fonction.multiplication(x, y);
            System.out.println("le resultat " + c);

        }

    if(expression.contains("/")){

        float x = Float.parseFloat(expression.split("\/")[0]);
        float y = Float.parseFloat(expression.split("\/")[1]);
        float c = fonction.divion(x, y);
        System.out.println("le resultat " + c);

    }


    do{
        System.out.println("voulez vous effecteur une autre operation");
        System.out.println("O pour Oui ");
        System.out.println("N pour Non ");
        String choix = sr.nextLine();

        if ((!(choix.equals("O")))&& (!(choix.equals("N"))))
        {
            Sonia =false;
            System.out.println("La valeur saisit n'est pas Correcte veulliez choisir N ou O seulement");
         }
        else if(choix.equals("N"))
           {
            noury=false;
            }
        else
                {
            System.out.println("Entrez une nouvelle valeur à calculer");

                }
        }while(Sonia);
    }

    }

}