code: public static String getHashFromString(String str) {
          try {
              java.security.MessageDigest md = java.security.MessageDigest.getInstance("SHA-256");
              byte[] array = md.digest(str.getBytes("UTF-8"));
              StringBuilder sb = new StringBuilder();
              for (byte anArray : array) {
                  sb.append(Integer.toHexString((anArray & 0xFF) | 0x100).substring(1, 3));
              }
              return sb.toString();
          } catch (java.security.NoSuchAlgorithmException | UnsupportedEncodingException e) {
              throw new IllegalArgumentException("Cannot calculate SHA-256 hash for :" + str, e);
          }
      }
docs: Generates a sha-256 hash from a string
  Taken from http://stackoverflow.com/questions/415953/generate-md5-hash-in-java
  
  @param str a {@link java.lang.String} object.
  @return a {@link java.lang.String} object.
  @since 0.7.2