Run Length Encoding

   public static void main(String[] args) throws Exception {

      Scanner kb = new Scanner(System.in);
      System.out.println("Input: ");
      String str = kb.nextLine();

      String Encoded = "";

      char ch=0;
      char oldCh=0;
      int count=0;
      int index=0;

      // Loop though the entire string
      while (index < str.length()) {
          // Grab next character and save it twice
          ch = str.charAt(index);
          // Set run length to 1
          count=1;
          // Look ahead (if possible)
          if ((index+1) < str.length()) {
              // Save for comparison
              oldCh = ch;
              // Bump index
              index++;
              // Fetch next character
              ch = str.charAt(index);
              // Calculate run length
              while ((ch == oldCh) && (index < str.length())) {
                  count++;  // Bump count
                  index++;  // Bump index
                  ch = str.charAt(index);   // Grab next char

                  // NOTE: Most run length encoding algorithms use
                  // a maximum run length, so I'll just toss this in there
                  // https://en.wikipedia.org/wiki/Run-length_encoding
                  if (count > 255) {
                      throw new Exception("Exceeded maximum run length (255)");
                  }
              }
              // Back up, and regurgitate the look ahead character
              index--;
              ch = oldCh;
          }
          // Emit run length only if required
          if (count > 1) {
              Encoded += count;
          }
          // Emit character
          Encoded += ch;
          // Move to next index
          index++;
      }

      System.out.println("Encoded: " + Encoded);
   }