As of yesterday yesterday in the Eclipse 4.6. integration build, we offer substring code completion by default in Eclipse JDK.
This brings this feature known from the IntelliJ IDE and the Eclipse Code Recommenders project to JDT users and will help to continue to enhance the Java Development Tools in Eclipse.
This feature was original developed within a Google Summer of Code project by Gábor Kövesdán with Noopur Gupta and myself as mentors. After the project finished, the JDT team polished this development quite a bit and activated it yesterday, including improve highlighting in the code proposal.
You find the latest and greatest integration build (I20160112-1800) on http://download.eclipse.org/eclipse/downloads/ if you want to try it out.