I have been solving all the problems till now in C now I want to shift to JAVA.
I know about the fast I/O methods in C but I want to learn those about those methods
in JAVA.
I would like to read good JAVA codes for these methods. where to find those?
whose codes should I refer?
You could try reading the Java submissions of people who took the minimum time in solving a particular problem. Filter the submissions for a problem by Java and AC and sort by time.