Two way that come to mind (there are probably more):
1) If you have a variable, call it aaa, of type A, you could type "aaa." then do CTRL-SPACE and a pop-up list of all public methods and fields should show up.
2) While editing A.java, right click and select Source > Override/Implement Methods. The resulting dialog box contains all non-private methods for all superclasses of A.
This can become even simpler with nWire, which is a code exploration plugin for Eclipse. It has a dynamic view which will automatically show you the associations you're looking for.