Compiler Warning: Recompile with -Xlint

Question

Note: C:\Documents and Settings\*\My Documents\InfixConvertor.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
Making a Infix to Postfix program. Doing some research, I understand that it does not need to be fixed, but I really wanna get rid of this. heres the code.
   import java.io.*;
   import java.util.*;
    public class InfixConvertor
   // initialize operator Stack
      private static Stack operatorS = new Stack();
       public static void main(String args[]) throws IOException
         String infix;
         Scanner in = new Scanner(System.in);
         System.out.println ("Enter a valid infix expression: ");
         infix = in.nextLine();
         System.out.println ("The Postfix expression is : " + IntoPostfix(infix));
   // method converts infix expression to postfix notation
       private static String IntoPostfix(String infix)
         StringTokenizer tokenizer = new StringTokenizer(infix);
      // divides the input into tokens for input
         String symbol, postfix = "";
         while (tokenizer.hasMoreTokens())
         // while there is input to be read
            symbol = tokenizer.nextToken();
         // if it's a number, add it to the string
            if (Character.isDigit(symbol.charAt(0)))
               postfix = postfix + " " + (Integer.parseInt(symbol));
            else if (symbol.equals("("))
            // push "("
               char operator = '(';
               operatorS.push(operator);
            else if (symbol.equals(")"))
            // push everything back to "("
               while (((Character)operatorS.peek()) != '(')
                  postfix = postfix + " " + operatorS.pop();
               operatorS.pop();
            else
            // print operatorS occurring before it that have greater precedence
               while (!operatorS.empty() && !(operatorS.peek()).equals("(")
               && prec(symbol.charAt(0)) <= prec((Character)operatorS.peek()))
                  postfix = postfix + " " + operatorS.pop();
               char operator = symbol.charAt(0);
               operatorS.push(operator);
         while (!operatorS.empty())
            postfix = postfix + " " + operatorS.pop();
         return postfix;
   // method compares operators to establish precedence
       private static int prec(char x)
         if (x == '+' || x == '-')
            return 1;
         if (x == '*' || x == '/')
            return 2;
         return 0;
   }Please help me out. Thanks
Julian

Answer 1

You use "-Xlint:unchecked" as one of your command-line options. So instead of
javac Thingy.javayou do this instead:
javac -Xlint:unchecked Thingy.javaOf course if you already have several command-line options when you do your compiling, then you just need one more.