Java Algorithms Reverse a String using Stack

import java.util.Stack;

class Reverser {/*  w ww  .  j a va  2s.  c  o  m*/
   private String input;
   private String output;

   public Reverser(String in) {
      input = in;
   }

   public String doRev(){
      Stack<Character> theStack = new Stack<>();
      for (int j = 0; j < input.length(); j++) {
         char ch = input.charAt(j); // get a char from input
         theStack.push(ch); // push it
      }
      output = "";
      while (!theStack.isEmpty()) {
         char ch = theStack.pop(); // pop a char,
         output = output + ch; // append to output
      }
      return output;
   }
}

public class Main {
   public static void main(String[] args) {
      Reverser theReverser = new Reverser("www.demo2s.com");
      String output = theReverser.doRev(); // use it
      System.out.println("Reversed: " + output);
   }
}