are your mock tests .
this include both free as well as paid mocks.
well you can solve the questions of the chapters that you have read so far in mocks.
They are not gonna ask that wat is hexadecimal of 12 or sumthin like that but there are methods like toHexString which convert decimal into hexadecimal you must know about these methods.they are given in chapter 3 of K & B.
hope this helps