Move the 'add' function  defn to outside of 'main' but inside the class
MathOp

are you new to java?
just pass parameters in add  func to add numbers
bye
ur soln is:

import java.io.*;

class MathOp
{
public static  void main(String args[])throws
IOException
{
System.out.println(" MENU
");
System.out.println(" 1. ADD
");
System.out.println(" 2. SUBTRACT
");
System.out.println(" 3. MULTIPLY
");
System.out.println(" 4. DIVIDE
");
System.out.println("Enter your Choice");

BufferedReader Cin = new
BufferedReader(new
InputStreamReader(System.in));
String choice;
choice =Cin.readLine();
int ch =Integer.parseInt(choice);

switch(ch)
{
case 1:

System.out.println("Add");
add();
break;
case 2:
System.out.println
("Subtract");
break;
case 3:
System.out.println
("Multiply");
break;
case 4:

System.out.println("Divide");
break;
}

}

void add()
{
System.out.println{"Add");
}


}

Define outside main method.....