// This appears in Core Web Programming from
// Prentice Hall Publishers, and may be freely used
// or adapted. 1997 Marty Hall, hall@apl.jhu.edu.

package cgi;                                                                    

public class URLDecoder {
  public static String decode(String encoded) {
    StringBuffer decoded = new StringBuffer();
    int i=0;
    String charCode;
    char currentChar, decodedChar;
    while(i < encoded.length()) {
      currentChar = encoded.charAt(i);
      if (currentChar == '+') {
        decoded.append(" ");
        i = i + 1;
      } else if (currentChar == '%') {
        charCode = encoded.substring(i+1, i+3);
        decodedChar
          = (char)Integer.parseInt(charCode, 16);
        decoded.append(decodedChar);
        i = i + 3;
      } else {
        decoded.append(currentChar);
        i = i + 1;
      }
    }
    return(decoded.toString());
  }

  public static void main(String[] args) {
    System.out.println(decode(args[0]));
  }
  
}