EDIT

	static public Integer Nz(Integer value){

		return (value == null ? 0 : value);

	}

	/**

	 * Concatenates the an Array of Strings, using the defined seperator.

	 * Null values are interpreted as empty Strings

	 * If all Strings are null a null is returned 

	 * @param strings

	 * @param seperator

	 * @return String 

	 */

	static public String concat(CharSequence seperator, String[] strings){

		String result = "";

		boolean allNull = true;

		for (String string : strings){

			if (string != null){

				if (result.length() > 0 && string.length() > 0){

					result += seperator;

				}

				result += string;

				allNull = false;

			}

		}

		//if all strings are null result should be null, not ""

		if (allNull){

			return null;

		}else {

			return result;

		}

	}

	static public String concat(CharSequence seperator, String string1, String string2){

		String[] strings = {string1, string2};

		return concat(seperator, strings);

	}