/* * Copyright (C) 2008 The Guava Authors * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.google.common.collect; import com.google.common.annotations.GwtCompatible; import java.util.Iterator; import java.util.NoSuchElementException; /** * An iterator that supports a one-element lookahead while iterating. * *
See the Guava User Guide article on
* {@code PeekingIterator}.
*
* @author Mick Killianey
* @since 2.0 (imported from Google Collections Library)
*/
@GwtCompatible
public interface PeekingIterator Calls to {@code peek()} should not change the state of the iteration,
* except that it may prevent removal of the most recent element via
* {@link #remove()}.
*
* @throws NoSuchElementException if the iteration has no more elements
* according to {@link #hasNext()}
*/
E peek();
/**
* {@inheritDoc}
*
* The objects returned by consecutive calls to {@link #peek()} then {@link
* #next()} are guaranteed to be equal to each other.
*/
@Override
E next();
/**
* {@inheritDoc}
*
* Implementations may or may not support removal when a call to {@link
* #peek()} has occurred since the most recent call to {@link #next()}.
*
* @throws IllegalStateException if there has been a call to {@link #peek()}
* since the most recent call to {@link #next()} and this implementation
* does not support this sequence of calls (optional)
*/
@Override
void remove();
}