java.util.Iterator Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 java.util;
/**
* An iterator over a sequence of objects, such as a collection.
*
* If a collection has been changed since the iterator was created,
* methods {@code next} and {@code hasNext()} may throw a {@code ConcurrentModificationException}.
* It is not possible to guarantee that this mechanism works in all cases of unsynchronized
* concurrent modification. It should only be used for debugging purposes. Iterators with this
* behavior are called fail-fast iterators.
*
*
Implementing {@link Iterable} and returning an {@code Iterator} allows your
* class to be used as a collection with the enhanced for loop.
*
* @param
* the type of object returned by the iterator.
*/
public interface Iterator {
/**
* Returns true if there is at least one more element, false otherwise.
* @see #next
*/
public boolean hasNext();
/**
* Returns the next object and advances the iterator.
*
* @return the next object.
* @throws NoSuchElementException
* if there are no more elements.
* @see #hasNext
*/
public E next();
/**
* Removes the last object returned by {@code next} from the collection.
* This method can only be called once between each call to {@code next}.
*
* @throws UnsupportedOperationException
* if removing is not supported by the collection being
* iterated.
* @throws IllegalStateException
* if {@code next} has not been called, or {@code remove} has
* already been called after the last call to {@code next}.
*/
public void remove();
}