In order to be able to see the source for a particular plug-in, it needs to be installed. This is achieved using the same installation dialog that has been covered previously in this book.
Go to Help | Install New Software and choose the repository that is associated with the release of Eclipse that is being used:
Ensure that the Group items by category checkbox is deselected. This will show all plug-ins, not just the main ones. Typically the source plug-ins are not shown in the main listing. In addition, deselecting this checkbox will result in a faster search in the next step.
Optionally deselect the Hide items that are already installed checkbox. This will ensure that the plug-ins show up even if they are already installed.
Search for source in the search box. This will result in a set of plug-ins being shown:
Select the following plug-ins and then click on Finish. If all the plug-ins are already installed, then the Finish button may be disabled:
Eclipse JDT Plug-in Developer Resources
Eclipse PDE Plug-in Developer Resources
Eclipse Platform Plug-in Developer Resources
Eclipse RCP Plug-in Developer Resources
What just happened?
When the developer resources are installed into Eclipse, a set of source plug-ins are installed. For example, for the org.eclipse.core.runtime plug-in, there will be a corresponding org.eclipse.core.runtime.source plug-in that contains the individual source files. These can be seen in the plugins/ directory inside the Eclipse install.
The developer resources are included in the IDE for Eclipse Committers package and the Eclipse SDK, but typically not included in other packages.