org.apache.commons.collections.iterators.SingletonIterator Maven / Gradle / Ivy
/*
* 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 org.apache.commons.collections.iterators;
import java.util.Iterator;
import java.util.NoSuchElementException;
import org.apache.commons.collections.ResettableIterator;
/**
* SingletonIterator is an {@link Iterator} over a single
* object instance.
*
* @since Commons Collections 2.0
* @version $Revision$ $Date$
*
* @author James Strachan
* @author Stephen Colebourne
* @author Rodney Waldhoff
*
* @deprecated Apache Commons Collections version 3.x is being deprecated from AEMaaCS. The upgraded version 4.4 of Commons Collections is already included as replacement. Customers are advised to upgrade to this version of the library. Please note: the package name was changed to org.apache.commons.collections4. Further note that there are AEM APIs currently exposing the old collections classes; these will be updated in upcoming releases.
*/
@Deprecated(since = "2021-04-30")
public class SingletonIterator implements Iterator, ResettableIterator {
/**
* Whether remove is allowed
*/
private final boolean removeAllowed;
/**
* Is the cursor before the first element
*/
private boolean beforeFirst = true;
/**
* Has the element been removed
*/
private boolean removed = false;
/**
* The object
*/
private Object object;
/**
* Constructs a new SingletonIterator where remove
* is a permitted operation.
*
* @param object the single object to return from the iterator
*/
public SingletonIterator(Object object) {
this(object, true);
}
/**
* Constructs a new SingletonIterator optionally choosing if
* remove is a permitted operation.
*
* @param object the single object to return from the iterator
* @param removeAllowed true if remove is allowed
* @since Commons Collections 3.1
*/
public SingletonIterator(Object object, boolean removeAllowed) {
super();
this.object = object;
this.removeAllowed = removeAllowed;
}
// -----------------------------------------------------------------------
/**
* Is another object available from the iterator?
*
* This returns true if the single object hasn't been returned yet.
*
* @return true if the single object hasn't been returned yet
*/
public boolean hasNext() {
return (beforeFirst && !removed);
}
/**
* Get the next object from the iterator.
*
* This returns the single object if it hasn't been returned yet.
*
* @return the single object
* @throws NoSuchElementException if the single object has already
* been returned
*/
public Object next() {
if (!beforeFirst || removed) {
throw new NoSuchElementException();
}
beforeFirst = false;
return object;
}
/**
* Remove the object from this iterator.
*
* @throws IllegalStateException if the next method has not
* yet been called, or the remove method has already
* been called after the last call to the next
* method.
* @throws UnsupportedOperationException if remove is not supported
*/
public void remove() {
if (removeAllowed) {
if (removed || beforeFirst) {
throw new IllegalStateException();
} else {
object = null;
removed = true;
}
} else {
throw new UnsupportedOperationException();
}
}
/**
* Reset the iterator to the start.
*/
public void reset() {
beforeFirst = true;
}
}