You need to add a .desktop file to the /home/QtPalmtop/apps/<tab_name> directory. Assign to the \"EXEC=\" line the name of the script that starts your java application. The \"standard\" naming convention for this script is \"runappname\", where \"appname\" is the name of your application.
Example runappname script:
$QPEDIR/bin/evm -Xprogressbar -XappName=$0 -cp $QPEDIR/java/myappname.jar myclassname
Java apps that install as IPKs usually do this for you (ex: jcryptpad, shoppinglist, etc.)