_284.java

package com.fishercoder.solutions;

import java.util.Iterator;
import java.util.LinkedList;
import java.util.Queue;

public class _284 {
    public static class Solution1 {
        public static class PeekingIterator implements Iterator<Integer> {

            private Queue<Integer> queue;

            public PeekingIterator(Iterator<Integer> iterator) {
                // initialize any member here.
                queue = new LinkedList<>();
                while (iterator.hasNext()) {
                    queue.add(iterator.next());
                }
            }

            // Returns the next element in the iteration without advancing the iterator.
            public Integer peek() {
                return queue.peek();
            }

            // hasNext() and next() should behave the same as in the Iterator interface.
            // Override them if needed.
            @Override
            public Integer next() {
                return queue.poll();
            }

            @Override
            public boolean hasNext() {
                return !queue.isEmpty();
            }
        }
    }
}