Where does Eclipse store the information regarding "Run Favorites" or "Debug Favorites"?

Solution

These are stored in the file launchConfigurationHistory.xml in the workspace .metadata/.plugins/org.eclipse.debug.ui directory.

The file contains various launch related settings, favorites are in the <favorites> sections.

Note: It is probably not safe to modify this file while Eclipse is running.

Update:

The launch configuration file itself name.launch in the .metadata/.plugins/org.eclipse.debug.core/.launches directory is also updated to say which favorites group it is in.

Update:

If a xxx.launch file is in a favorites group it contains something like:

<listAttribute key="org.eclipse.debug.ui.favoriteGroups">
<listEntry value="org.eclipse.debug.ui.launchGroup.run"/>
</listAttribute>

(along with lots of other launch related entries)

Update:

You can look at the launch configurations in a plugin using:

ILaunchManager manager = DebugPlugin.getDefault().getLaunchManager(); 

ILaunchConfiguration [] configs = manager.getLaunchConfigurations();

The IDebugUIConstants.ATTR_FAVORITE_GROUPS attribute of the ILaunchConfiguration should contain any favorites groups the launch is in.