public String convertData(String s, int indexColumn) {
		String r = "";
		if (increasing.get(indexColumn) == -1) { 
			//TO DO: invert String
			for (int i = 0; i < s.length(); i++) {
				char ch = s.charAt(i);
				char t;
				if ('0' <= ch && ch <= '9') { 
					t = (char) ('9' - ch + '0');
				} else if ('a' <= ch && ch <= 'z') {
					t = (char) ('z' - ch + 'a');
				} else if ('A' <= ch && ch <= 'Z') {
					t = (char) ('Z' - ch + 'A');
				} else {
					t = ch;
				}
				r += t;
			}
		} else {
			r += s;
		}
		//r = r.replaceAll("" + (char) 0, " "); //Convert NULL value
		return r;
	}