You can have a combined IDE. I use one that combines the Eclipse SDK, including Java, CDT, Android, JavaScript, and a bunch of other things all in one. It's a bit clunky to do but can be done. Just go to the Help -> Install New Software... menu item and bring up the install dialog.

First install one of them, Java or C/C++. Then after launching it, select the "Luna - http://download.eclipse.org/releases/luna" item in the "Work with:" selector. Then find the other IDE components you would like in the list and install it.

It's not a great experience and I plan on spending some time this summer working on a real installer and maybe get some of the bigger chunks into the Eclipse Marketplace which has a much nicer UI and experience. But I'm glad you brought this up because confirms for me that we need a good answer so people like yourself can get the IDE flavors you want without having to install multiple IDEs.

I think this is still a problem. Please correct me if I am wrong. As a workaround- I am downloading the zip files, then renaming the outputted folder, and then creating separate shortcuts (eclipse-c, eclipse-java, eclipse-js).