Java访问MySQL ，判断符合条件的记录是否为空

Java 访问MySQL数据库：

Connection con = null;
Statement stmt = null;
ResultSet rs = null;
Class.forName(driver);
con = DriverManager.getConnection(url, user, password);
stmt = con.createStatement();
sqlstr = String.format("SELECT objectId FROM %s WHERE className=59",tableName_1);
rs = stmt.executeQuery(sqlstr);

除了用COUNT()判断记录rs为空之外还有什么别的方法？