As Java evolves it grows continually in terms of numbers of classes. Type browsing is getting more and more a tiring task even when using wildcards and the camel case search notation. Just too many internal classes appear that are not supposed to be used by clients anyway (they make up the internal implementation of Java APIs). So this is a good reason to hide them anyway.
So go to Preferences->Java->Appearance->Type Filters and add any package or type filter. I have found useful to add at least