SQL Developer of version 3.2.10.09.57 displays numbers as 'oracle.sql.NUMBER@66a35419 (the part after @ is not constant and changes each execution) even for simple select count(*) from dual.
At the same time 'Run Script (F5)' shows only the header
and no query result.
Searching the forum, I see a similar complaint noted against 3.1.07.42. Run statement produces query results showing oracle.sql.NUMBER, possibly due to a corrupt install (either due to unzip issues, or possibly not unzipping into an empty directory). See the following thread: SQLDev 3.1: Number-Fields in tables show "oracle.sql.NUMBER@..."
It seems that this is exactly my issue.
But I'm thinking now how to fix it. There is only one download option for Ubuntu and it is downloaded and unpacked correctly I'm sure.
openjdk has no file tzmappings and zi directory and I see no other options to get them rather than installing of Sun's java or coping them from Windows machine...
Among my various Sun/Oracle java installs, I also have openjdk-6.0.21 for Windows. Its jre\lib contains the zi directory and the tzmappings file. I started up SQL Developer 3.2.1 directly with its java.exe (bypassing our own sqldeveloper.exe which blocks start-up due to a version checking (format) issue with openjdk).
With this configuration I was not able to reproduce the oracle.sql.NUMBER issue using "select count(*) from dual".
So I'm not sure if your environment poses any special obstacles, but there must be some way for you to get the correct combination of items installed to overcome this issue. Hope it will not be too painful.
It appears as though you'll need the official oracle java. I installed oracle-java7-installer from a ppa (http://www.webupd8.org/2012/01/install-oracle-java-jdk-7-in-ubuntu-via.html), and the number nonsense is fixed.
You might want to actually use java6, but java7 is working for me.