IteratorExtensions.java 文件源码

/**
 * Returns an Iterator containing all elements starting from the head of the source up to and excluding the first
 * element that violates the predicate. The resulting Iterator is a lazily computed view, so any modifications to the
 * underlying Iterators will be reflected on iteration. The result does not support {@link Iterator#remove()}
 * 
 * @param iterator
 *            the elements from which to take. May not be <code>null</code>.
 * @param predicate
 *            the predicate which decides whether to keep taking elements. May not be <code>null</code>.
 * @return the taken elements
 * @since 2.7
 */
public static <T> Iterator<T> takeWhile(final Iterator<? extends T> iterator, final Function1<? super T, Boolean> predicate) {
    if (iterator == null)
        throw new NullPointerException("iterator");
    if (predicate == null)
        throw new NullPointerException("predicate");
    return new AbstractIterator<T>() {
        @Override
        protected T computeNext() {
            if (!iterator.hasNext())
                return endOfData();
            T next = iterator.next();
            if (predicate.apply(next)) {
                return next;
            } else {
                return endOfData();
            }
        }
    };
}