A concrete class can't have abstract methods, so it must implement all the abstract methods from its ancestors. You need to implement both BuildNow() and buildNow() (I'm guessing these are two different methods and not a typo.)
All code in my posts, unless a source is explicitly mentioned, is my own.
But UDI has not implemented the interfaces methods..It has declared the method as abstract.So it is up to Nonc to implement UDI's buildNow method as well as Buildables buildNow method.But how can it do this?
Yes Duran, and your exam is on Friday, just open K&B 6 book, go to chapter 5 page 382 Table 5-2, here all runtime exceptions are given, also which are thrown by JVM and which are by Programmer, mug up this, make a small diary or note, write down this as a small quiz, it will help you in last hours before your exam.
Make all such notes, at least to see one time before your exam.