Tomcat，结果集中没有数据？

Question

I'm having trouble getting any sense back from my mySQL database. I'm passing it a valid query that should return a single row. However it only ever returns me 0, the intial value of int results

public String getResultSet(String query) throws SQLException{
            ResultSet rs = null;
            int results=0;
            try {
                con = ds.getConnection();
                Statement stmt = (Statement) con.createStatement();
                rs = stmt.executeQuery(query);

                    while(rs.next()){                   
                        results = rs.getInt("location_id");             
                    }           

                } catch (Exception ex ){               
            } finally {
                if (con != null) con.close();
            }           
            return Integer.toString(results);           
        }

No errors are being thrown, could some advise what I'm doing wrong?

TIA

Answer 1

It looks like you have a catch block for Exception with an empty body. This will catch and silently ignore any SQL etcetera exceptions. Then you will drop out of the try/catch, and return results ... which will still be zero.

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What you are doing is "squashing" the exception; ie catching it and throwing it away without doing any recovery or error reporting. This is bad practice . Worse still, you are doing this for Exception . That means you are doing it not only for the checked exceptions that you (possibly) expect to occur, but also for a whole range of unchecked exceptions that you cannot anticipate.

Answer 2

No exceptions are being thrown because you are catching them all without printing them. If there are any, you'd never see them because your catch block is empty.