When you start Java Explorer, at least two processes are run. The first process displays the Java Explorer GUI and runs under SDK 1.4. The second process is the runtime process. This process instantiates and manages all Java objects that belong to the currently open project. The runtime process can run under any JDK. You can configure the JDK in the Project Settings dialog box.
The runtime process is started with the JDK that is configured and is initialized with the static classpath entries. After the runtime process is initialized, the UrlClassLoader is initialized with the dynamic classpath entries.