To view the Java Platform Manager, select Tools > Java Platforms. Alternatively, right-click on a project, choose Properties from the context menu, select Platform, and select the Manage Emulators button.
The Java Platform Manager is a tool for managing different versions of the Java Development Kit (JDK) and customizing Java platforms that your applications depend on. You can register new platforms or add source files and Javadoc™ documents to the existing platforms. For Java ME purposes, the platforms are emulators or SDK platforms for mobile devices.
The Java ME Platform SDK pre-registers CDC, J2ME™ (CLDC and MIDP) and J2SE™ (the JDK serves as the default platform).
The J2SE platform includes the Java SE SDK. The CDC platform includes the CDC and BD-J stacks.