It is advisable to use a JDK and not a JRE in your development environment for App Engine applications.
If you plan to use JSP (Java Server Pages) in your application, then you have to use the JDK. Often we setup Eclipse and install the Google Plugin for Eclipse in a hurry and overlook the fact that Eclipse is still using a JRE. The problem manifests itself more when you are trying to deploy the application to a live App Engine instance and the error comes back to you.
To ensure that you are using a JDK, do the following:
- Go to Window -> Preferences in Eclipse IDE.
- Go to Java -> Installed JREs as shown below:
- Ensure that the selected option is a JDK and not a JRE.
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