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Re: NullPointerException when calling ResultSet.absolute(int)

From: Oliver Jowett <oliver(at)opencloud(dot)com>
To: Clemens Eisserer <linuxhippy(at)gmail(dot)com>
Cc: pgsql-jdbc(at)postgresql(dot)org
Subject: Re: NullPointerException when calling ResultSet.absolute(int)
Date: 2005-08-28 21:40:14
Message-ID: 43122F3E.3040002@opencloud.com (view raw or flat)
Thread:
Lists: pgsql-jdbc
Clemens Eisserer wrote:

> Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
> 	at org.postgresql.jdbc2.AbstractJdbc2ResultSet.absolute(AbstractJdbc2ResultSet.java:184)
> 	at CATableModel.getValueAt(CATableModel.java:88)
> 	at javax.swing.JTable.getValueAt(JTable.java:1852)

From your later email this was because the ResultSet was closed. FWIW,
more recent drivers should throw an appropriate SQLException in this
case, instead of NPE.

> btw. is there a more intelligent way to find out how many lines have
> been selected than starting two queries where the one query just
> queries the row-count?
> I did not find any better solution, but for complex queries this is
> really inefficient :-(

Either you can use two queries, or use a scrollable ResultSet and call
ResultSet.last() / ResultSet.getRow(). The second approach causes the
entire ResultSet to be loaded into the Java heap, though, so it's not so
good for large results.

-O

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