Welcome to JavaRanch, Prabha Dhandapani! Note that The Beginners Forum is likely a more appropriate place to ask such a question. This JavaRanch forum, where we are now, was intended for questions related to JavaRanch and the Big Moose Saloon.
Concerning answering your question, perhaps a quick example with less than complete descriptions will help. Consider the following interface definitions, which exemplify one interface extending another.If a class is defined to implement InterfaceB, then it must implement all methods declared in InterfaceA and in InterfaceB (else the class must be declared abstract). If something isn't clear, just ask another question. I hope to see you 'round the Ranch!