Java support comes shipped with Emacs in the form of java-mode.
List of notable Java modes
- malabar-mode is a Java mode which was originally by Espen Wiborg. It has Maven integration, JUnit integration, support for Java generics, simple refactoring support and more. (no longer maintained)
- JDEE, Java Development Environment for Emacs, has intelligent Java code completion among other things. (quite outdated and no longer maintained)
- java-mode provides basic Java 1.4 syntax highlighting.