284_Peeking_Iterator.java

classPeekingIteratorimplementsIterator<Integer> {
privateIntegernext;
privateIterator<Integer> it;

publicPeekingIterator(Iterator<Integer> iterator) {
it = iterator;
next = it.next();
 }

// Returns the next element in the iteration without advancing the iterator.
publicIntegerpeek() {
returnnext;
 }

// hasNext() and next() should behave the same as in the Iterator interface.
// Override them if needed.
@Override
publicIntegernext() {
Integerresult = next;

if (it.hasNext()) {
next = it.next();
 } else {
next = null;
 }

returnresult;
 }

@Override
publicbooleanhasNext() {
returnnext != null;
 }
}