hi friend,

you are defining the add and sub method at the wrong place. Try the code below :

package roseindia.net;
import java.util.Scanner; 
public class g {

    public static void main(String[] args) {
        int d,x,y;
        int a;

        Scanner s=new Scanner(System.in);
        System.out.println("Enter the first number");
        x=s.nextInt();
        System.out.println("Enter the second number");
        y=s.nextInt();

        System.out.println("Enter ur choice");
        System.out.println("1 For Add.");
        System.out.println("2 For Subtract.");
        a=s.nextInt();
        switch(a)
        {   case 1:add(x,y);
                break;
        case 2:sub(x,y);
        break;
        default :System.out.println("invalid choice");
        break;
        }
        }
    public static void add(int x, int y){
        int d= x+y;
        System.out.println("Addition of two numbers : "+d);
    }
    public static void sub(int x, int y){
        int d= x-y;
        System.out.println("Subtraction of two numbers : "+d);
    }
    }

thanx dear