public static ArrayList<String> extractKeywords(String input) {
		if (input==null) {
			return null;
		}
		ArrayList<String> results=  new ArrayList<String>();
		int beginIndex = input.indexOf("keyword:");
		beginIndex += "keyword:".length();
		int endIndex = beginIndex;
		while (endIndex <= input.length()) {
			while (" ".contains(input.substring(endIndex, endIndex+1))) {
				endIndex++;
			}
			beginIndex = endIndex;
			while (!" ,;".contains(input.substring(endIndex, endIndex+1))) {
				endIndex++;
			}
			String tempKeyword = input.substring(beginIndex, endIndex).toLowerCase();
			if (!" \t\n".contains(tempKeyword) && !trival.contains(tempKeyword)) {
				results.add(tempKeyword);
			}
			if (input.charAt(endIndex) == ';') {
				break;
			}
			endIndex++;
		}
		return results;
	}