Compared to how well you're coddled in something like Netbeans/eclipse, it's tough to be satisfied in Emacs. They'll search the entire classpath (not just the classes you've written) and find every match that could be usable in the given situation (according to your import declarations), using your project definition for class file resolution.

On C++, it's harder when you start using templates. Seems only systems with tightly-integrated compilers do a decent job here.