- /*
- * Copyright 2002-2004 The Apache Software Foundation
- *
- * 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 org.apache.commons.collections;
-
- import java.lang.reflect.Array;
- import java.lang.reflect.Method;
- import java.util.ArrayList;
- import java.util.Collection;
- import java.util.Comparator;
- import java.util.Dictionary;
- import java.util.Enumeration;
- import java.util.Iterator;
- import java.util.List;
- import java.util.ListIterator;
- import java.util.Map;
-
- import org.apache.commons.collections.iterators.ArrayIterator;
- import org.apache.commons.collections.iterators.ArrayListIterator;
- import org.apache.commons.collections.iterators.CollatingIterator;
- import org.apache.commons.collections.iterators.EmptyIterator;
- import org.apache.commons.collections.iterators.EmptyListIterator;
- import org.apache.commons.collections.iterators.EmptyMapIterator;
- import org.apache.commons.collections.iterators.EmptyOrderedIterator;
- import org.apache.commons.collections.iterators.EmptyOrderedMapIterator;
- import org.apache.commons.collections.iterators.EnumerationIterator;
- import org.apache.commons.collections.iterators.FilterIterator;
- import org.apache.commons.collections.iterators.FilterListIterator;
- import org.apache.commons.collections.iterators.IteratorChain;
- import org.apache.commons.collections.iterators.IteratorEnumeration;
- import org.apache.commons.collections.iterators.ListIteratorWrapper;
- import org.apache.commons.collections.iterators.LoopingIterator;
- import org.apache.commons.collections.iterators.ObjectArrayIterator;
- import org.apache.commons.collections.iterators.ObjectArrayListIterator;
- import org.apache.commons.collections.iterators.ObjectGraphIterator;
- import org.apache.commons.collections.iterators.SingletonIterator;
- import org.apache.commons.collections.iterators.SingletonListIterator;
- import org.apache.commons.collections.iterators.TransformIterator;
- import org.apache.commons.collections.iterators.UnmodifiableIterator;
- import org.apache.commons.collections.iterators.UnmodifiableListIterator;
- import org.apache.commons.collections.iterators.UnmodifiableMapIterator;
-
- /**
- * Provides static utility methods and decorators for {@link Iterator}
- * instances. The implementations are provided in the iterators subpackage.
- * <p>
- * WARNING: Due to human error certain binary incompatabilities were introduced
- * between Commons Collections 2.1 and 3.0. The class remained source and test
- * compatible, so if you can recompile all your classes and dependencies
- * everything is OK. Those methods which are binary incompatible are marked as
- * such, together with alternate solutions that are binary compatible
- * against versions 2.1.1 and 3.1.
- *
- * @since Commons Collections 2.1
- * @version $Revision: 1.27 $ $Date: 2004/05/26 21:53:46 $
- *
- * @author Stephen Colebourne
- * @author Phil Steitz
- */
- public class IteratorUtils {
- // validation is done in this class in certain cases because the
- // public classes allow invalid states
-
- /**
- * An iterator over no elements.
- * <p>
- * WARNING: This constant is binary incompatible with Commons Collections 2.1 and 2.1.1.
- * Use <code>EmptyIterator.INSTANCE</code> for compatability with Commons Collections 2.1.1.
- */
- public static final ResettableIterator EMPTY_ITERATOR = EmptyIterator.RESETTABLE_INSTANCE;
- /**
- * A list iterator over no elements.
- * <p>
- * WARNING: This constant is binary incompatible with Commons Collections 2.1 and 2.1.1.
- * Use <code>EmptyListIterator.INSTANCE</code> for compatability with Commons Collections 2.1.1.
- */
- public static final ResettableListIterator EMPTY_LIST_ITERATOR = EmptyListIterator.RESETTABLE_INSTANCE;
- /**
- * An ordered iterator over no elements.
- */
- public static final OrderedIterator EMPTY_ORDERED_ITERATOR = EmptyOrderedIterator.INSTANCE;
- /**
- * A map iterator over no elements.
- */
- public static final MapIterator EMPTY_MAP_ITERATOR = EmptyMapIterator.INSTANCE;
- /**
- * An ordered map iterator over no elements.
- */
- public static final OrderedMapIterator EMPTY_ORDERED_MAP_ITERATOR = EmptyOrderedMapIterator.INSTANCE;
-
- /**
- * IteratorUtils is not normally instantiated.
- */
- public IteratorUtils() {
- }
-
- // Empty
- //-----------------------------------------------------------------------
- /**
- * Gets an empty iterator.
- * <p>
- * This iterator is a valid iterator object that will iterate over
- * nothing.
- * <p>
- * WARNING: This method is binary incompatible with Commons Collections 2.1 and 2.1.1.
- * Use <code>EmptyIterator.INSTANCE</code> for compatability with Commons Collections 2.1.1.
- *
- * @return an iterator over nothing
- */
- public static ResettableIterator emptyIterator() {
- return EMPTY_ITERATOR;
- }
-
- /**
- * Gets an empty list iterator.
- * <p>
- * This iterator is a valid list iterator object that will iterate
- * over nothing.
- * <p>
- * WARNING: This method is binary incompatible with Commons Collections 2.1 and 2.1.1.
- * Use <code>EmptyListIterator.INSTANCE</code> for compatability with Commons Collections 2.1.1.
- *
- * @return a list iterator over nothing
- */
- public static ResettableListIterator emptyListIterator() {
- return EMPTY_LIST_ITERATOR;
- }
-
- /**
- * Gets an empty ordered iterator.
- * <p>
- * This iterator is a valid iterator object that will iterate
- * over nothing.
- *
- * @return an ordered iterator over nothing
- */
- public static OrderedIterator emptyOrderedIterator() {
- return EMPTY_ORDERED_ITERATOR;
- }
-
- /**
- * Gets an empty map iterator.
- * <p>
- * This iterator is a valid map iterator object that will iterate
- * over nothing.
- *
- * @return a map iterator over nothing
- */
- public static MapIterator emptyMapIterator() {
- return EMPTY_MAP_ITERATOR;
- }
-
- /**
- * Gets an empty ordered map iterator.
- * <p>
- * This iterator is a valid map iterator object that will iterate
- * over nothing.
- *
- * @return a map iterator over nothing
- */
- public static OrderedMapIterator emptyOrderedMapIterator() {
- return EMPTY_ORDERED_MAP_ITERATOR;
- }
-
- // Singleton
- //-----------------------------------------------------------------------
- /**
- * Gets a singleton iterator.
- * <p>
- * This iterator is a valid iterator object that will iterate over
- * the specified object.
- * <p>
- * WARNING: This method is binary incompatible with Commons Collections 2.1 and 2.1.1.
- * Use <code>new SingletonIterator(object)</code> for compatability.
- *
- * @param object the single object over which to iterate
- * @return a singleton iterator over the object
- */
- public static ResettableIterator singletonIterator(Object object) {
- return new SingletonIterator(object);
- }
-
- /**
- * Gets a singleton list iterator.
- * <p>
- * This iterator is a valid list iterator object that will iterate over
- * the specified object.
- *
- * @param object the single object over which to iterate
- * @return a singleton list iterator over the object
- */
- public static ListIterator singletonListIterator(Object object) {
- return new SingletonListIterator(object);
- }
-
- // Arrays
- //-----------------------------------------------------------------------
- /**
- * Gets an iterator over an object array.
- * <p>
- * WARNING: This method is binary incompatible with Commons Collections 2.1 and 2.1.1.
- * Use <code>new ArrayIterator(array)</code> for compatability.
- *
- * @param array the array over which to iterate
- * @return an iterator over the array
- * @throws NullPointerException if array is null
- */
- public static ResettableIterator arrayIterator(Object[] array) {
- return new ObjectArrayIterator(array);
- }
-
- /**
- * Gets an iterator over an object or primitive array.
- * <p>
- * This method will handle primitive arrays as well as object arrays.
- * The primitives will be wrapped in the appropriate wrapper class.
- *
- * @param array the array over which to iterate
- * @return an iterator over the array
- * @throws IllegalArgumentException if the array is not an array
- * @throws NullPointerException if array is null
- */
- public static ResettableIterator arrayIterator(Object array) {
- return new ArrayIterator(array);
- }
-
- /**
- * Gets an iterator over the end part of an object array.
- * <p>
- * WARNING: This method is binary incompatible with Commons Collections 2.1 and 2.1.1.
- * Use <code>new ArrayIterator(array,start)</code> for compatability.
- *
- * @param array the array over which to iterate
- * @param start the index to start iterating at
- * @return an iterator over part of the array
- * @throws IndexOutOfBoundsException if start is less than zero or greater
- * than the length of the array
- * @throws NullPointerException if array is null
- */
- public static ResettableIterator arrayIterator(Object[] array, int start) {
- return new ObjectArrayIterator(array, start);
- }
-
- /**
- * Gets an iterator over the end part of an object or primitive array.
- * <p>
- * This method will handle primitive arrays as well as object arrays.
- * The primitives will be wrapped in the appropriate wrapper class.
- *
- * @param array the array over which to iterate
- * @param start the index to start iterating at
- * @return an iterator over part of the array
- * @throws IllegalArgumentException if the array is not an array
- * @throws IndexOutOfBoundsException if start is less than zero or greater
- * than the length of the array
- * @throws NullPointerException if array is null
- */
- public static ResettableIterator arrayIterator(Object array, int start) {
- return new ArrayIterator(array, start);
- }
-
- /**
- * Gets an iterator over part of an object array.
- * <p>
- * WARNING: This method is binary incompatible with Commons Collections 2.1 and 2.1.1.
- * Use <code>new ArrayIterator(array,start,end)</code> for compatability.
- *
- * @param array the array over which to iterate
- * @param start the index to start iterating at
- * @param end the index to finish iterating at
- * @return an iterator over part of the array
- * @throws IndexOutOfBoundsException if array bounds are invalid
- * @throws IllegalArgumentException if end is before start
- * @throws NullPointerException if array is null
- */
- public static ResettableIterator arrayIterator(Object[] array, int start, int end) {
- return new ObjectArrayIterator(array, start, end);
- }
-
- /**
- * Gets an iterator over part of an object or primitive array.
- * <p>
- * This method will handle primitive arrays as well as object arrays.
- * The primitives will be wrapped in the appropriate wrapper class.
- *
- * @param array the array over which to iterate
- * @param start the index to start iterating at
- * @param end the index to finish iterating at
- * @return an iterator over part of the array
- * @throws IllegalArgumentException if the array is not an array
- * @throws IndexOutOfBoundsException if array bounds are invalid
- * @throws IllegalArgumentException if end is before start
- * @throws NullPointerException if array is null
- */
- public static ResettableIterator arrayIterator(Object array, int start, int end) {
- return new ArrayIterator(array, start, end);
- }
-
- //-----------------------------------------------------------------------
- /**
- * Gets a list iterator over an object array.
- *
- * @param array the array over which to iterate
- * @return a list iterator over the array
- * @throws NullPointerException if array is null
- */
- public static ResettableListIterator arrayListIterator(Object[] array) {
- return new ObjectArrayListIterator(array);
- }
-
- /**
- * Gets a list iterator over an object or primitive array.
- * <p>
- * This method will handle primitive arrays as well as object arrays.
- * The primitives will be wrapped in the appropriate wrapper class.
- *
- * @param array the array over which to iterate
- * @return a list iterator over the array
- * @throws IllegalArgumentException if the array is not an array
- * @throws NullPointerException if array is null
- */
- public static ResettableListIterator arrayListIterator(Object array) {
- return new ArrayListIterator(array);
- }
-
- /**
- * Gets a list iterator over the end part of an object array.
- *
- * @param array the array over which to iterate
- * @param start the index to start iterating at
- * @return a list iterator over part of the array
- * @throws IndexOutOfBoundsException if start is less than zero
- * @throws NullPointerException if array is null
- */
- public static ResettableListIterator arrayListIterator(Object[] array, int start) {
- return new ObjectArrayListIterator(array, start);
- }
-
- /**
- * Gets a list iterator over the end part of an object or primitive array.
- * <p>
- * This method will handle primitive arrays as well as object arrays.
- * The primitives will be wrapped in the appropriate wrapper class.
- *
- * @param array the array over which to iterate
- * @param start the index to start iterating at
- * @return a list iterator over part of the array
- * @throws IllegalArgumentException if the array is not an array
- * @throws IndexOutOfBoundsException if start is less than zero
- * @throws NullPointerException if array is null
- */
- public static ResettableListIterator arrayListIterator(Object array, int start) {
- return new ArrayListIterator(array, start);
- }
-
- /**
- * Gets a list iterator over part of an object array.
- *
- * @param array the array over which to iterate
- * @param start the index to start iterating at
- * @param end the index to finish iterating at
- * @return a list iterator over part of the array
- * @throws IndexOutOfBoundsException if array bounds are invalid
- * @throws IllegalArgumentException if end is before start
- * @throws NullPointerException if array is null
- */
- public static ResettableListIterator arrayListIterator(Object[] array, int start, int end) {
- return new ObjectArrayListIterator(array, start, end);
- }
-
- /**
- * Gets a list iterator over part of an object or primitive array.
- * <p>
- * This method will handle primitive arrays as well as object arrays.
- * The primitives will be wrapped in the appropriate wrapper class.
- *
- * @param array the array over which to iterate
- * @param start the index to start iterating at
- * @param end the index to finish iterating at
- * @return a list iterator over part of the array
- * @throws IllegalArgumentException if the array is not an array
- * @throws IndexOutOfBoundsException if array bounds are invalid
- * @throws IllegalArgumentException if end is before start
- * @throws NullPointerException if array is null
- */
- public static ResettableListIterator arrayListIterator(Object array, int start, int end) {
- return new ArrayListIterator(array, start, end);
- }
-
- // Unmodifiable
- //-----------------------------------------------------------------------
- /**
- * Gets an immutable version of an {@link Iterator}. The returned object
- * will always throw an {@link UnsupportedOperationException} for
- * the {@link Iterator#remove} method.
- *
- * @param iterator the iterator to make immutable
- * @return an immutable version of the iterator
- */
- public static Iterator unmodifiableIterator(Iterator iterator) {
- return UnmodifiableIterator.decorate(iterator);
- }
-
- /**
- * Gets an immutable version of a {@link ListIterator}. The returned object
- * will always throw an {@link UnsupportedOperationException} for
- * the {@link Iterator#remove}, {@link ListIterator#add} and
- * {@link ListIterator#set} methods.
- *
- * @param listIterator the iterator to make immutable
- * @return an immutable version of the iterator
- */
- public static ListIterator unmodifiableListIterator(ListIterator listIterator) {
- return UnmodifiableListIterator.decorate(listIterator);
- }
-
- /**
- * Gets an immutable version of a {@link MapIterator}. The returned object
- * will always throw an {@link UnsupportedOperationException} for
- * the {@link Iterator#remove}, {@link MapIterator#setValue(Object)} methods.
- *
- * @param mapIterator the iterator to make immutable
- * @return an immutable version of the iterator
- */
- public static MapIterator unmodifiableMapIterator(MapIterator mapIterator) {
- return UnmodifiableMapIterator.decorate(mapIterator);
- }
-
- // Chained
- //-----------------------------------------------------------------------
- /**
- * Gets an iterator that iterates through two {@link Iterator}s
- * one after another.
- *
- * @param iterator1 the first iterators to use, not null
- * @param iterator2 the first iterators to use, not null
- * @return a combination iterator over the iterators
- * @throws NullPointerException if either iterator is null
- */
- public static Iterator chainedIterator(Iterator iterator1, Iterator iterator2) {
- return new IteratorChain(iterator1, iterator2);
- }
-
- /**
- * Gets an iterator that iterates through an array of {@link Iterator}s
- * one after another.
- *
- * @param iterators the iterators to use, not null or empty or contain nulls
- * @return a combination iterator over the iterators
- * @throws NullPointerException if iterators array is null or contains a null
- */
- public static Iterator chainedIterator(Iterator[] iterators) {
- return new IteratorChain(iterators);
- }
-
- /**
- * Gets an iterator that iterates through a collections of {@link Iterator}s
- * one after another.
- *
- * @param iterators the iterators to use, not null or empty or contain nulls
- * @return a combination iterator over the iterators
- * @throws NullPointerException if iterators collection is null or contains a null
- * @throws ClassCastException if the iterators collection contains the wrong object type
- */
- public static Iterator chainedIterator(Collection iterators) {
- return new IteratorChain(iterators);
- }
-
- // Collated
- //-----------------------------------------------------------------------
- /**
- * Gets an iterator that provides an ordered iteration over the elements
- * contained in a collection of ordered {@link Iterator}s.
- * <p>
- * Given two ordered {@link Iterator}s <code>A</code> and <code>B</code>,
- * the {@link Iterator#next()} method will return the lesser of
- * <code>A.next()</code> and <code>B.next()</code>.
- * <p>
- * The comparator is optional. If null is specified then natural order is used.
- *
- * @param comparator the comparator to use, may be null for natural order
- * @param iterator1 the first iterators to use, not null
- * @param iterator2 the first iterators to use, not null
- * @return a combination iterator over the iterators
- * @throws NullPointerException if either iterator is null
- */
- public static Iterator collatedIterator(Comparator comparator, Iterator iterator1, Iterator iterator2) {
- return new CollatingIterator(comparator, iterator1, iterator2);
- }
-
- /**
- * Gets an iterator that provides an ordered iteration over the elements
- * contained in an array of {@link Iterator}s.
- * <p>
- * Given two ordered {@link Iterator}s <code>A</code> and <code>B</code>,
- * the {@link Iterator#next()} method will return the lesser of
- * <code>A.next()</code> and <code>B.next()</code> and so on.
- * <p>
- * The comparator is optional. If null is specified then natural order is used.
- *
- * @param comparator the comparator to use, may be null for natural order
- * @param iterators the iterators to use, not null or empty or contain nulls
- * @return a combination iterator over the iterators
- * @throws NullPointerException if iterators array is null or contains a null
- */
- public static Iterator collatedIterator(Comparator comparator, Iterator[] iterators) {
- return new CollatingIterator(comparator, iterators);
- }
-
- /**
- * Gets an iterator that provides an ordered iteration over the elements
- * contained in a collection of {@link Iterator}s.
- * <p>
- * Given two ordered {@link Iterator}s <code>A</code> and <code>B</code>,
- * the {@link Iterator#next()} method will return the lesser of
- * <code>A.next()</code> and <code>B.next()</code> and so on.
- * <p>
- * The comparator is optional. If null is specified then natural order is used.
- *
- * @param comparator the comparator to use, may be null for natural order
- * @param iterators the iterators to use, not null or empty or contain nulls
- * @return a combination iterator over the iterators
- * @throws NullPointerException if iterators collection is null or contains a null
- * @throws ClassCastException if the iterators collection contains the wrong object type
- */
- public static Iterator collatedIterator(Comparator comparator, Collection iterators) {
- return new CollatingIterator(comparator, iterators);
- }
-
- // Object Graph
- //-----------------------------------------------------------------------
- /**
- * Gets an iterator that operates over an object graph.
- * <p>
- * This iterator can extract multiple objects from a complex tree-like object graph.
- * The iteration starts from a single root object.
- * It uses a <code>Transformer</code> to extract the iterators and elements.
- * Its main benefit is that no intermediate <code>List</code> is created.
- * <p>
- * For example, consider an object graph:
- * <pre>
- * |- Branch -- Leaf
- * | \- Leaf
- * |- Tree | /- Leaf
- * | |- Branch -- Leaf
- * Forest | \- Leaf
- * | |- Branch -- Leaf
- * | | \- Leaf
- * |- Tree | /- Leaf
- * |- Branch -- Leaf
- * |- Branch -- Leaf</pre>
- * The following <code>Transformer</code>, used in this class, will extract all
- * the Leaf objects without creating a combined intermediate list:
- * <pre>
- * public Object transform(Object input) {
- * if (input instanceof Forest) {
- * return ((Forest) input).treeIterator();
- * }
- * if (input instanceof Tree) {
- * return ((Tree) input).branchIterator();
- * }
- * if (input instanceof Branch) {
- * return ((Branch) input).leafIterator();
- * }
- * if (input instanceof Leaf) {
- * return input;
- * }
- * throw new ClassCastException();
- * }</pre>
- * <p>
- * Internally, iteration starts from the root object. When next is called,
- * the transformer is called to examine the object. The transformer will return
- * either an iterator or an object. If the object is an Iterator, the next element
- * from that iterator is obtained and the process repeats. If the element is an object
- * it is returned.
- * <p>
- * Under many circumstances, linking Iterators together in this manner is
- * more efficient (and convenient) than using nested for loops to extract a list.
- *
- * @param root the root object to start iterating from, null results in an empty iterator
- * @param transformer the transformer to use, see above, null uses no effect transformer
- * @return a new object graph iterator
- * @since Commons Collections 3.1
- */
- public static Iterator objectGraphIterator(Object root, Transformer transformer) {
- return new ObjectGraphIterator(root, transformer);
- }
-
- // Transformed
- //-----------------------------------------------------------------------
- /**
- * Gets an iterator that transforms the elements of another iterator.
- * <p>
- * The transformation occurs during the next() method and the underlying
- * iterator is unaffected by the transformation.
- *
- * @param iterator the iterator to use, not null
- * @param transform the transform to use, not null
- * @return a new transforming iterator
- * @throws NullPointerException if either parameter is null
- */
- public static Iterator transformedIterator(Iterator iterator, Transformer transform) {
- if (iterator == null) {
- throw new NullPointerException("Iterator must not be null");
- }
- if (transform == null) {
- throw new NullPointerException("Transformer must not be null");
- }
- return new TransformIterator(iterator, transform);
- }
-
- // Filtered
- //-----------------------------------------------------------------------
- /**
- * Gets an iterator that filters another iterator.
- * <p>
- * The returned iterator will only return objects that match the specified
- * filtering predicate.
- *
- * @param iterator the iterator to use, not null
- * @param predicate the predicate to use as a filter, not null
- * @return a new filtered iterator
- * @throws NullPointerException if either parameter is null
- */
- public static Iterator filteredIterator(Iterator iterator, Predicate predicate) {
- if (iterator == null) {
- throw new NullPointerException("Iterator must not be null");
- }
- if (predicate == null) {
- throw new NullPointerException("Predicate must not be null");
- }
- return new FilterIterator(iterator, predicate);
- }
-
- /**
- * Gets a list iterator that filters another list iterator.
- * <p>
- * The returned iterator will only return objects that match the specified
- * filtering predicate.
- *
- * @param listIterator the list iterator to use, not null
- * @param predicate the predicate to use as a filter, not null
- * @return a new filtered iterator
- * @throws NullPointerException if either parameter is null
- */
- public static ListIterator filteredListIterator(ListIterator listIterator, Predicate predicate) {
- if (listIterator == null) {
- throw new NullPointerException("ListIterator must not be null");
- }
- if (predicate == null) {
- throw new NullPointerException("Predicate must not be null");
- }
- return new FilterListIterator(listIterator, predicate);
- }
-
- // Looping
- //-----------------------------------------------------------------------
- /**
- * Gets an iterator that loops continuously over the supplied collection.
- * <p>
- * The iterator will only stop looping if the remove method is called
- * enough times to empty the collection, or if the collection is empty
- * to start with.
- *
- * @param coll the collection to iterate over, not null
- * @return a new looping iterator
- * @throws NullPointerException if the collection is null
- */
- public static ResettableIterator loopingIterator(Collection coll) {
- if (coll == null) {
- throw new NullPointerException("Collection must not be null");
- }
- return new LoopingIterator(coll);
- }
-
- // Views
- //-----------------------------------------------------------------------
- /**
- * Gets an iterator that provides an iterator view of the given enumeration.
- *
- * @param enumeration the enumeration to use
- * @return a new iterator
- */
- public static Iterator asIterator(Enumeration enumeration) {
- if (enumeration == null) {
- throw new NullPointerException("Enumeration must not be null");
- }
- return new EnumerationIterator(enumeration);
- }
-
- /**
- * Gets an iterator that provides an iterator view of the given enumeration
- * that will remove elements from the specified collection.
- *
- * @param enumeration the enumeration to use
- * @param removeCollection the collection to remove elements from
- * @return a new iterator
- */
- public static Iterator asIterator(Enumeration enumeration, Collection removeCollection) {
- if (enumeration == null) {
- throw new NullPointerException("Enumeration must not be null");
- }
- if (removeCollection == null) {
- throw new NullPointerException("Collection must not be null");
- }
- return new EnumerationIterator(enumeration, removeCollection);
- }
-
- /**
- * Gets an enumeration that wraps an iterator.
- *
- * @param iterator the iterator to use, not null
- * @return a new enumeration
- * @throws NullPointerException if iterator is null
- */
- public static Enumeration asEnumeration(Iterator iterator) {
- if (iterator == null) {
- throw new NullPointerException("Iterator must not be null");
- }
- return new IteratorEnumeration(iterator);
- }
-
- /**
- * Gets a list iterator based on a simple iterator.
- * <p>
- * As the wrapped Iterator is traversed, a LinkedList of its values is
- * cached, permitting all required operations of ListIterator.
- *
- * @param iterator the iterator to use, not null
- * @return a new iterator
- * @throws NullPointerException if iterator parameter is null
- */
- public static ListIterator toListIterator(Iterator iterator) {
- if (iterator == null) {
- throw new NullPointerException("Iterator must not be null");
- }
- return new ListIteratorWrapper(iterator);
- }
-
- /**
- * Gets an array based on an iterator.
- * <p>
- * As the wrapped Iterator is traversed, an ArrayList of its values is
- * created. At the end, this is converted to an array.
- *
- * @param iterator the iterator to use, not null
- * @return an array of the iterator contents
- * @throws NullPointerException if iterator parameter is null
- */
- public static Object[] toArray(Iterator iterator) {
- if (iterator == null) {
- throw new NullPointerException("Iterator must not be null");
- }
- List list = toList(iterator, 100);
- return list.toArray();
- }
-
- /**
- * Gets an array based on an iterator.
- * <p>
- * As the wrapped Iterator is traversed, an ArrayList of its values is
- * created. At the end, this is converted to an array.
- *
- * @param iterator the iterator to use, not null
- * @param arrayClass the class of array to create
- * @return an array of the iterator contents
- * @throws NullPointerException if iterator parameter is null
- * @throws NullPointerException if arrayClass is null
- * @throws ClassCastException if the arrayClass is invalid
- */
- public static Object[] toArray(Iterator iterator, Class arrayClass) {
- if (iterator == null) {
- throw new NullPointerException("Iterator must not be null");
- }
- if (arrayClass == null) {
- throw new NullPointerException("Array class must not be null");
- }
- List list = toList(iterator, 100);
- return list.toArray((Object[]) Array.newInstance(arrayClass, list.size()));
- }
-
- /**
- * Gets a list based on an iterator.
- * <p>
- * As the wrapped Iterator is traversed, an ArrayList of its values is
- * created. At the end, the list is returned.
- *
- * @param iterator the iterator to use, not null
- * @return a list of the iterator contents
- * @throws NullPointerException if iterator parameter is null
- */
- public static List toList(Iterator iterator) {
- return toList(iterator, 10);
- }
-
- /**
- * Gets a list based on an iterator.
- * <p>
- * As the wrapped Iterator is traversed, an ArrayList of its values is
- * created. At the end, the list is returned.
- *
- * @param iterator the iterator to use, not null
- * @param estimatedSize the initial size of the ArrayList
- * @return a list of the iterator contents
- * @throws NullPointerException if iterator parameter is null
- * @throws IllegalArgumentException if the size is less than 1
- */
- public static List toList(Iterator iterator, int estimatedSize) {
- if (iterator == null) {
- throw new NullPointerException("Iterator must not be null");
- }
- if (estimatedSize < 1) {
- throw new IllegalArgumentException("Estimated size must be greater than 0");
- }
- List list = new ArrayList(estimatedSize);
- while (iterator.hasNext()) {
- list.add(iterator.next());
- }
- return list;
- }
-
- /**
- * Gets a suitable Iterator for the given object.
- * <p>
- * This method can handles objects as follows
- * <ul>
- * <li>null - empty iterator
- * <li>Iterator - returned directly
- * <li>Enumeration - wrapped
- * <li>Collection - iterator from collection returned
- * <li>Map - values iterator returned
- * <li>Dictionary - values (elements) enumeration returned as iterator
- * <li>array - iterator over array returned
- * <li>object with iterator() public method accessed by reflection
- * <li>object - singleton iterator
- * </ul>
- *
- * @param obj the object to convert to an iterator
- * @return a suitable iterator, never null
- */
- public static Iterator getIterator(Object obj) {
- if (obj == null) {
- return emptyIterator();
-
- } else if (obj instanceof Iterator) {
- return (Iterator) obj;
-
- } else if (obj instanceof Collection) {
- return ((Collection) obj).iterator();
-
- } else if (obj instanceof Object[]) {
- return new ObjectArrayIterator((Object[]) obj);
-
- } else if (obj instanceof Enumeration) {
- return new EnumerationIterator((Enumeration) obj);
-
- } else if (obj instanceof Map) {
- return ((Map) obj).values().iterator();
-
- } else if (obj instanceof Dictionary) {
- return new EnumerationIterator(((Dictionary) obj).elements());
-
- } else if (obj != null && obj.getClass().isArray()) {
- return new ArrayIterator(obj);
-
- } else {
- try {
- Method method = obj.getClass().getMethod("iterator", null);
- if (Iterator.class.isAssignableFrom(method.getReturnType())) {
- Iterator it = (Iterator) method.invoke(obj, null);
- if (it != null) {
- return it;
- }
- }
- } catch (Exception ex) {
- // ignore
- }
- return singletonIterator(obj);
- }
- }
-
- }