If you plan on using JDeveloper with Oracle BPM you'll need to get on JDK 1.6.
Are you asking how to switch JDKs after JDeveloper has already been installed? Instead of finding all of the configuration files that JDeveloper uses to identify the JDK it's going to use, I believe the best, safest and by far the quickest approach is to simply reinstall 18.104.22.168.
When you reinstall it, either
- use the JDK that is bundled with JDeveloper (JDK 1.6.0_24) by selecting the "Complete" installation or
- download and install a JDK 1.6.0_24+ and then reinstall JDeveloper by selecting the "Custom" installation -> uncheck the bundled JDK checkbox and select "Browse" button to find and select the JDK 1.6 that you installed
I recently had the same issue when I migrated my JDev folders to my new laptop from the old laptop. New one had only JDK 1.7 and I faced the same issue.
Install JDK 1.6 as suggested by others then you need to modify the jdev.conf file under <JDev_Home>/jdeveloper/jdev/bin folder to provide the path to JDK 1.6.
After this change you should able to drag and drop the data objects for the HT.