Menu.java

import java.util.*;

public class Menu {
   
   public static void main(String[] args) {
      System.out.println("Main: Menu");
      Convert convert = new Convert();
         
      boolean flag = true;
      int x = 0;
      int value;
      
      Scanner stdin = new Scanner(System.in);
      
      while (flag)
      {      
         try {
            System.out.println("1) Method 1");
            System.out.println("2) Method 2");
            System.out.println("3) Method 3");
            System.out.println("4) Exit");
            System.out.print("Enter X: ");
            x = stdin.nextInt();
         }         
         catch (Exception e) {
            System.out.println("Exception");
            stdin.nextLine();
            x = 0;
         }         
      
         if (x == 1) {
            System.out.print("Enter Value: ");
            value = stdin.nextInt();
            value = convert.method1(value);
            System.out.println("Value: " + value);
         }
         else if (x == 2) {
            System.out.print("Enter Value: ");
            value = stdin.nextInt();
            value = convert.method2(value);
            System.out.println("Value: " + value);
         }
         else if (x == 3) {
            System.out.print("Enter Value: ");
            value = stdin.nextInt();
            value = convert.method3(value);
            System.out.println("Value: " + value);
         }         
         else if (x == 4) {
            System.out.println("Exit");
            flag = false;
         }
         else {
            System.out.println("Error");
         }
      } // end while       
   } // end main
} // end Menu

Convert.java

public class Convert {

   Convert() {
      System.out.println("Convert()");
   }
   
   int method1(int x) {
      x = x * 10;
      return x;
   }
   
   int method2(int x) {
      x = x * 20;
      return x;
   }
   
   int method3(int x) {
      x = x * 10;
      return x;
   }
   
   public static void main(String[] args) {
      System.out.println("Main: Convert"); 
   } // end main
} // end Convert