leetcode Peeking Iterator

题目链接

// Java Iterator interface reference:
// https://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html
class PeekingIterator implements Iterator<Integer> {

    private Integer cache;
    private boolean hasCache=false;
    Iterator<Integer> originIterator;
    public PeekingIterator(Iterator<Integer> iterator) {
        // initialize any member here.

        originIterator=iterator;
    }

    // Returns the next element in the iteration without advancing the iterator.
    public Integer peek() {
        if(hasCache)
        {
            return cache;
        }
        else
        {
            hasCache=true;
            cache=originIterator.next();
            return cache;
        }
    }

    // hasNext() and next() should behave the same as in the Iterator interface.
    // Override them if needed.
    @Override
    public Integer next() {
        if(hasCache)
        {
            hasCache=false;
            return cache;
        }
        else
        {
            return originIterator.next();
        }
    }

    @Override
    public boolean hasNext() {
        if(hasCache)
        {
            return true;
        }
        else
        {
            return originIterator.hasNext();
        }
    }
}