assignment add sub mul div

import java.io.*;
public class zzzz
{

                static BufferedReader in = new BufferedReader (new InputStreamReader(System.in));
        public static void main(String args []) throws IOException
        {
                        int x= 0;
                        double y= 0;
                        double z= 0;
                        System.out.println("[1]Addition");
                        System.out.println("[2]Substraction");
                        System.out.println("[3]Multiplication");
                        System.out.println("[4]Division");
                        System.out.println("enter operation nuber: ");
                        x=Integer.parseInt(in.readLine());
                        System.out.println("enter Value1: ");
                        z=Double.parseDouble(in.readLine());
                        System.out.println("enter Value2: ");
                        y=Double.parseDouble(in.readLine());
                        if (x==1)
                        {
                            add(z,y);
                        }
                        else if (x==2)
                        {
                            sub(z,y);
                        }
                        else if (x==3)
                        {
                            mul(z,y);
                        }
                        else if (x==4)
                        {
                            div(z,y);
                        }
                        else{
                            System.out.println("Invalid Operation number");
                        }

        }
        public static void add(double z,double y)
        {
            double n=z+y;
            System.out.println("The Result is: "+n);
        }
        public static void sub(double z,double y)
        {
            double n=z-y;
            System.out.println("The Result is: "+n);
        }
        public static void mul(double z,double y)
        {
            double n=z*y;
            System.out.println("The Result is: "+n);
        }
        public static void div(double z,double y)
        {
            double n=z/y;
            System.out.println("The Result is: "+n);
        }
}