int startFrom, String operator) {
try {
queryStr = queryStr.trim();
QueryParser parser = new QueryParser("contents", analyzer);
Operator op = QueryParser.AND_OPERATOR;
if (QueryParser.AND_OPERATOR.toString().equalsIgnoreCase(operator)){
parser.setDefaultOperator(QueryParser.AND_OPERATOR);
} else {
parser.setDefaultOperator(QueryParser.OR_OPERATOR);
}