Java,MySQL - NULL resultset

Question

I got a method to get an integer from a MySQL table

public int getAddressID(String postcode) throws SQLException {
    String q = "SELECT PK_ADDRESS_ID FROM tbl_addresses WHERE postcode =" + "\"" + postcode + "\"";
    System.out.println(q);
    ResultSet rs = executeSearch(q);
    int pc = 0;
    while (rs.next()) {
        String str = rs.getString("postcode");
        pc = Integer.parseInt(str);
    }
    System.out.println(pc);
    return pc;
}

The query seems fine but somehow when I initialize some variable and use this method, I get the error Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: "". Am I missing anything? Thanks for any help!

The idea is input a postcode and then find ADDRESS_ID. postcode value is unique. — Tri Nguyen
– Tri Nguyen, Commented Nov 16, 2016 at 7:14
if your return address_id value is not digit you can't convert to int. — Ye Win
– Ye Win, Commented Nov 16, 2016 at 7:16
@Ye Win: I think this points into the right direction. getString("postcode") tries to read postcode, but the query does not return it. — mm759
– mm759, Commented Nov 16, 2016 at 7:18
NOTE: Use a preparedStatement if you receive the postcode from an input. You are open to injection inserting a String like this into the query. — AxelH
– AxelH, Commented Nov 16, 2016 at 7:21

Scary Wombat · Accepted Answer · 2016-11-16 07:16:34Z

3

Your SQL is SELECT PK_ADDRESS_ID ...

but then you try to get

rs.getString("postcode");

change to

rs.getString("PK_ADDRESS_ID");

answered Nov 16, 2016 at 7:16

Scary Wombat

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N00b Pr0grammer · Accepted Answer · 2016-11-16 09:35:21Z

-1

It seems you are selecting PK_ADDRESS_ID column from the database and the value returned is either "" (empty) or NULL. So it shows NumberFormatException which cannot be converted as a Number.

So please check the value you get from the database.

edited Nov 16, 2016 at 9:35

N00b Pr0grammer

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answered Nov 16, 2016 at 7:16

Anands23

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