Eclipse Kepler Java 8

Now, after Java 8 is released, there is a feature patch, but only for Kepler SR2 (4.3.2). Installation via

Help > Install New Software... > 'Work with': http://download.eclipse.org/eclipse/updates/4.3-P-builds/

see Tutorial Installing Java 8 on Eclipse Kepler

Have a look at this bug report from time to time for progress on Java 8 in Eclipse's JDT.

EDIT: For Kepler you need SR2 (4.3.2) and the Java 8 feature patch. Starting with I20140318-0830 all Luna (4.4) builds contain support for Java 8 "out-of-the-box". The final version of Eclipse Luna (4.4) will be released at the end of June 2014.