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Java Forum / Databases / August 2006Testing for empty columns in resultset
This seems too trivial. After populating a resultset with a query, what is the best way to test if a column is null to avoid the dreaded null pointer exception when attempting a tostring() call. thanks > This seems too trivial. > After populating a resultset with a query, what is the best way to test > if a column is null to avoid the dreaded null pointer exception when > attempting a tostring() call. > thanks ResultSet.wasNull() (very important if you use getInt() or other get methods that return primitive data types) As an alternative you can always test your return value (if it's an Object) agains null ;), e.g: String value = rs.getString(1); if (value != null) .... Thomas  SignatureIt's not a RootKit - it's a Sony > > This seems too trivial. > > After populating a resultset with a query, what is the best way to test [quoted text clipped - 15 lines] > -- > It's not a RootKit - it's a Sony I was hoping for something like an isnull test. String value = rs.getString(1); requires an extra creation of a String var wasNull requires the getString first to set it's status anyway Oh well, I'm justing longing for the good old days of 'C' where if you could think of it you could do it. :-) Thanks > I was hoping for something like an isnull test. > String value = rs.getString(1); requires an extra creation of a String > var > wasNull requires the getString first to set it's status anyway > Oh well, I'm justing longing for the good old days of 'C' where if you > could think of it you could do it. :-) How should the driver decide that without fetching the value from the server? There is no way around the getXXXX() Btw: I doubt that rs.getString(1) will create a *new* String (in the sense that additional memory is allocated to hold the character data) If the driver simply does a "return value" where value is the String that it created, no additional memory is required (except for your local reference). Even a "return new String(value)" does not copy the character data. The new String merely references the character array of the source (this is possible as Strings are imutable) Thomas SignatureIt's not a RootKit - it's a Sony > This seems too trivial. > After populating a resultset with a query, what is the best way to test > if a column is null to avoid the dreaded null pointer exception when > attempting a tostring() call. If all you are going to do with your ResultSet is to print it, I would do System.out.println(rs.getObject(x)+" somestring"+... which would produce null somestring I've tried this with integer, varchar and double columns, but I don't know if it will work for all types (I guess that depends on how the getObject() method is implemented in the driver) Signaturedt Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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