public static String list2String(List<String> list) {
    	StringBuilder sb = new StringBuilder();
    	for (String s : list) {
    		sb.append(s + ",");
    	}
    	String string = sb.toString().trim();
    	if (list.size() > 0) {
    		string = string.substring(0, string.length() - 1);
    	}
    	
    	String s = sb.toString();
    	sb.setLength(0);
    	sb = null;
    	return s;
    }