First you have to create a generic Application by selecting from File -> New -> General -> Generic Application

Name the application and create a new Extension project for the application by selecting File -> New -> Projects -> Extension Project

The Create Extension Project wizard will help you specify the project details

The new Extension project will have the structure like

The properties of the project is to be configured as shown in the figure

Open the extension.xml from META-INF folder. In the overview tab you will find General, Dependencies and Hooks panels

General – Will have all general information like name, version, owner etc

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Dependencies – Will have references to the extension dependencies. The classpath reference is also included

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Hooks – Will have the points at which the extension will be added to the Jdeveloper ide.

Each individual hook allows an extension to provide specific binding information to plug into different areas of an IDE. Here are the main areas where extensions plug-in:

1. Menus and commands through the menu-hook,
2. Document model through the document-hook,
3. IDE events through the ide-listener-hook,
4. Custom editors through the editor-hook,
5. IDE preferences and project settings through the property-hook,
6. Log pages through the log-hook
7. New wizards through the wizard-hook, and
8. The compiler through the build-system-hook.
9. The feature-hook allows extensions to appear in an IDE’s extension management UI as features that can be enabled/disabled.
10. The custom-hook and hook-handlers allows extensions to define their own extension points.

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Running the extension is to right-click the project and say Run Extension

The deployed extension will be seen from Tools menu and preferences

The sample project can be downloaded from here

For details on the tags in the extension.xml file, see the file JDEV_HOME/jdev/doc/extension/ide-extension-packaging.html