Eclipse ' s Code assist

Suddenly found that there is a class without code assist function, and other classes are also, the new class also has, but when the code copied to the new class or not, and tried various methods, including delete workspace/.metadata/.plugin/ Org.eclipse.jdt.core under the index file, also still no, System.out, this., do not prompt;

What the heck is this?

Then suddenly found that as long as there is that class, a class in other projects will have problems, but clearly tell him to use the jar specified in the MAVEN library, it does not show red, it is determined to rely on the work space of its projects, OK, the whole world is quiet, all normal.

Also tried to java/editor/content assist/advanced under the project to select all, not a, do not include in the MAVEN library type?

Blame.