// GenericsNote: Converted.
/*
* Copyright 2001-2004 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.collections15;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;
import java.util.Set;
import org.apache.commons.collections15.collection.UnmodifiableCollection;
/**
* Provides utility methods and decorators for {@link Collection} instances.
*
* @author Rodney Waldhoff
* @author Paul Jack
* @author Stephen Colebourne
* @author Steve Downey
* @author Herve Quiroz
* @author Peter KoBek
* @author Matthew Hawthorne
* @author Janek Bogucki
* @author Phil Steitz
* @author Steven Melzer
* @author Matt Hall, John Watkinson, Jon Schewe
* @version $Revision: 1.1 $ $Date: 2005/10/11 17:05:19 $
* @since Commons Collections 1.0
*/
public class CollectionUtils {
/**
* Constant to avoid repeated object creation
*/
private static Integer INTEGER_ONE = Integer.valueOf(1);
/**
* An empty unmodifiable collection. The JDK provides empty Set and List
* implementations which could be used for this purpose. However they could
* be cast to Set or List which might be undesirable. This implementation
* only implements Collection.
*/
// public static final Collection EMPTY_COLLECTION =
// UnmodifiableCollection.decorate(new ArrayList());
/**
* <code>CollectionUtils</code> should not normally be instantiated.
*/
public CollectionUtils() {
}
/**
* Returns a {@link Collection} containing the union of the given
* {@link Collection}s.
* <p/>
* The cardinality of each element in the returned {@link Collection} will
* be equal to the maximum of the cardinality of that element in the two
* given {@link Collection}s.
*
* @param a
* the first collection, must not be null
* @param b
* the second collection, must not be null
* @return the union of the two collections15
* @see Collection#addAll
*/
public static <E> Collection<E> union(final Collection<? extends E> a,
final Collection<? extends E> b) {
ArrayList<E> list = new ArrayList<E>();
Map mapa = getCardinalityMap(a);
Map mapb = getCardinalityMap(b);
Set<E> elts = new HashSet<E>(a);
elts.addAll(b);
Iterator<E> it = elts.iterator();
while (it.hasNext()) {
E obj = it.next();
for (int i = 0, m = Math.max(getFreq(obj, mapa),
getFreq(obj, mapb)); i < m; i++) {
list.add(obj);
}
}
return list;
}
/**
* Returns a {@link Collection} containing the intersection of the given
* {@link Collection}s.
* <p/>
* The cardinality of each element in the returned {@link Collection} will
* be equal to the minimum of the cardinality of that element in the two
* given {@link Collection}s.
*
* @param a
* the first collection, must not be null
* @param b
* the second collection, must not be null
* @return the intersection of the two collections15
* @see Collection#retainAll
* @see #containsAny
*/
public static <E> Collection<E> intersection(
final Collection<? extends E> a, final Collection<? extends E> b) {
ArrayList<E> list = new ArrayList<E>();
Map mapa = getCardinalityMap(a);
Map mapb = getCardinalityMap(b);
Set<E> elts = new HashSet<E>(a);
elts.addAll(b);
Iterator<E> it = elts.iterator();
while (it.hasNext()) {
E obj = it.next();
for (int i = 0, m = Math.min(getFreq(obj, mapa),
getFreq(obj, mapb)); i < m; i++) {
list.add(obj);
}
}
return list;
}
/**
* Returns a {@link Collection} containing the exclusive disjunction
* (symmetric difference) of the given {@link Collection}s.
* <p/>
* The cardinality of each element <i>e</i> in the returned
* {@link Collection} will be equal to
* <tt>max(cardinality(<i>e</i>,<i>a</i>),cardinality(<i>e</i>,<i>b</i>)) - min(cardinality(<i>e</i>,<i>a</i>),cardinality(<i>e</i>,<i>b</i>))</tt>
* .
* <p/>
* This is equivalent to
* <tt>{@link #subtract subtract}({@link #union union(a,b)},{@link #intersection intersection(a,b)})</tt>
* or
* <tt>{@link #union union}({@link #subtract subtract(a,b)},{@link #subtract subtract(b,a)})</tt>
* .
*
* @param a
* the first collection, must not be null
* @param b
* the second collection, must not be null
* @return the symmetric difference of the two collections15
*/
public static <E> Collection<E> disjunction(final Collection<E> a,
final Collection<E> b) {
ArrayList<E> list = new ArrayList<E>();
Map mapa = getCardinalityMap(a);
Map mapb = getCardinalityMap(b);
Set<E> elts = new HashSet<E>(a);
elts.addAll(b);
Iterator<E> it = elts.iterator();
while (it.hasNext()) {
E obj = it.next();
for (int i = 0, m = ((Math.max(getFreq(obj, mapa),
getFreq(obj, mapb)))
- (Math.min(getFreq(obj, mapa),
getFreq(obj, mapb)))); i < m; i++) {
list.add(obj);
}
}
return list;
}
/**
* Returns a new {@link Collection} containing <tt><i>a</i> - <i>b</i></tt>.
* The cardinality of each element <i>e</i> in the returned
* {@link Collection} will be the cardinality of <i>e</i> in <i>a</i> minus
* the cardinality of <i>e</i> in <i>b</i>, or zero, whichever is greater.
*
* @param a
* the collection to subtract from, must not be null
* @param b
* the {@link Iterable} to subtract, must not be null
* @return a new collection with the results
* @see Collection#removeAll
*/
public static <E> Collection<E> subtract(final Collection<? extends E> a,
final Iterable<? extends E> b) {
ArrayList<E> list = new ArrayList<E>(a);
for (E e : b) {
list.remove(e);
}
return list;
}
/**
* Returns <code>true</code> iff at least one element is in both
* collections15.
* <p/>
* In other words, this method returns <code>true</code> iff the
* {@link #intersection} of <i>coll1</i> and <i>coll2</i> is not empty.
*
* @param coll1
* the first collection, must not be null
* @param coll2
* the first collection, must not be null
* @return <code>true</code> iff the intersection of the collections15 is
* non-empty
* @see #intersection
* @since 2.1
*/
public static <E> boolean containsAny(final Collection<? extends E> coll1,
final Collection<? extends E> coll2) {
if (coll1.size() < coll2.size()) {
for (Iterator it = coll1.iterator(); it.hasNext();) {
if (coll2.contains(it.next())) {
return true;
}
}
} else {
for (Iterator it = coll2.iterator(); it.hasNext();) {
if (coll1.contains(it.next())) {
return true;
}
}
}
return false;
}
// public static void main(String[] args) {
// List<String> l1 = new ArrayList<String>();
// l1.add("Test");
// List<Integer> l2 = new ArrayList<Integer>();
// l2.add(1);
// containsAny(l1, l2);
// }
/**
* Returns a {@link Map} mapping each unique element in the given
* {@link Iterable} to an {@link Integer} representing the number of
* occurrences of that element in the {@link Iterable}.
* <p/>
* Only those elements present in the Iterable will appear as keys in the
* map.
*
* @param iterable
* the collection to get the cardinality map for, must not be
* null
* @return the populated cardinality map
*/
public static <E> Map<E, java.lang.Integer> getCardinalityMap(
final Iterable<E> iterable) {
Map<E, Integer> count = new HashMap<E, Integer>();
for (Iterator<E> it = iterable.iterator(); it.hasNext();) {
E obj = it.next();
Integer c = count.get(obj);
if (c == null) {
count.put(obj, INTEGER_ONE);
} else {
count.put(obj, Integer.valueOf(c.intValue() + 1));
}
}
return count;
}
/**
* Returns <tt>true</tt> iff <i>a</i> is a sub-collection of <i>b</i>, that
* is, iff the cardinality of <i>e</i> in <i>a</i> is less than or equal to
* the cardinality of <i>e</i> in <i>b</i>, for each element <i>e</i> in
* <i>a</i>.
*
* @param a
* the first (sub?) collection, must not be null
* @param b
* the second (super?) collection, must not be null
* @return <code>true</code> iff <i>a</i> is a sub-collection of <i>b</i>
* @see #isProperSubCollection
* @see Collection#containsAll
*/
public static <E> boolean isSubCollection(final Iterable<? extends E> a,
final Iterable<? extends E> b) {
Map mapa = getCardinalityMap(a);
Map mapb = getCardinalityMap(b);
for (E obj : a) {
if (getFreq(obj, mapa) > getFreq(obj, mapb)) {
return false;
}
}
return true;
}
/**
* Returns <tt>true</tt> iff <i>a</i> is a <i>proper</i> sub-collection of
* <i>b</i>, that is, iff the cardinality of <i>e</i> in <i>a</i> is less
* than or equal to the cardinality of <i>e</i> in <i>b</i>, for each
* element <i>e</i> in <i>a</i>, and there is at least one element <i>f</i>
* such that the cardinality of <i>f</i> in <i>b</i> is strictly greater
* than the cardinality of <i>f</i> in <i>a</i>.
* <p/>
* The implementation assumes
* <ul>
* <li><code>a.size()</code> and <code>b.size()</code> represent the total
* cardinality of <i>a</i> and <i>b</i>, resp.</li>
* <li><code>a.size() < Integer.MAXVALUE</code></li>
* </ul>
*
* @param a
* the first (sub?) collection, must not be null
* @param b
* the second (super?) collection, must not be null
* @return <code>true</code> iff <i>a</i> is a <i>proper</i> sub-collection
* of <i>b</i>
* @see #isSubCollection
* @see Collection#containsAll
*/
public static <E> boolean isProperSubCollection(
final Collection<? extends E> a, final Collection<? extends E> b) {
return (a.size() < b.size()) && CollectionUtils.isSubCollection(a, b);
}
/**
* Returns <tt>true</tt> iff the given {@link Collection}s contain exactly
* the same elements with exactly the same cardinalities.
* <p/>
* That is, iff the cardinality of <i>e</i> in <i>a</i> is equal to the
* cardinality of <i>e</i> in <i>b</i>, for each element <i>e</i> in
* <i>a</i> or <i>b</i>.
*
* @param a
* the first collection, must not be null
* @param b
* the second collection, must not be null
* @return <code>true</code> iff the collections15 contain the same elements
* with the same cardinalities.
*/
public static <E> boolean isEqualCollection(final Collection<? extends E> a,
final Collection<? extends E> b) {
if (a.size() != b.size()) {
return false;
}
Map mapa = getCardinalityMap(a);
Map mapb = getCardinalityMap(b);
if (mapa.size() != mapb.size()) {
return false;
}
Iterator it = mapa.keySet().iterator();
while (it.hasNext()) {
Object obj = it.next();
if (getFreq(obj, mapa) != getFreq(obj, mapb)) {
return false;
}
}
return true;
}
// /**
// * Returns the number of occurrences of <i>obj</i> in <i>coll</i>.
// *
// * @param obj the object to find the cardinality of
// * @param coll the collection to search
// * @return the the number of occurrences of obj in coll
// */
// public static <E> int cardinality(E obj, final Collection<? super E>
// coll) {
// if (coll instanceof Set) {
// return (coll.contains(obj) ? 1 : 0);
// }
// if (coll instanceof Bag) {
// return ((Bag) coll).getCount(obj);
// }
// int count = 0;
// if (obj == null) {
// for (Iterator it = coll.iterator(); it.hasNext();) {
// if (it.next() == null) {
// count++;
// }
// }
// } else {
// for (Iterator it = coll.iterator(); it.hasNext();) {
// if (obj.equals(it.next())) {
// count++;
// }
// }
// }
// return count;
// }
/**
* Finds the first element in the given iterable which matches the given
* predicate.
* <p/>
* If the input iterable or predicate is null, or no element of the iterable
* matches the predicate, null is returned.
*
* @param iterable
* the iterable to search, may be null
* @param predicate
* the predicate to use, may be null
* @return the first element of the iterable which matches the predicate or
* null if none could be found
*/
public static <E> E find(Iterable<E> iterable,
Predicate<? super E> predicate) {
if (iterable != null && predicate != null) {
for (Iterator<E> iter = iterable.iterator(); iter.hasNext();) {
E item = iter.next();
if (predicate.evaluate(item)) {
return item;
}
}
}
return null;
}
/**
* Executes the given closure on each element in the iterable.
* <p/>
* If the input iterable or closure is null, there is no change made.
*
* @param iterable
* the iterable to get the input from, may be null
* @param closure
* the closure to perform, may be null
*/
public static <E> void forAllDo(Iterable<E> iterable,
Closure<? super E> closure) {
if (iterable != null && closure != null) {
for (Iterator<E> it = iterable.iterator(); it.hasNext();) {
closure.execute(it.next());
}
}
}
/**
* Filter the iterable by applying a Predicate to each element. If the
* predicate returns false, remove the element.
* <p/>
* If the input iterable or predicate is null, there is no change made.
*
* @param iterable
* the iterable to get the input from, may be null
* @param predicate
* the predicate to use as a filter, may be null
*/
public static <E> void filter(Iterable<E> iterable,
Predicate<? super E> predicate) {
if (iterable != null && predicate != null) {
for (Iterator<E> it = iterable.iterator(); it.hasNext();) {
if (predicate.evaluate(it.next()) == false) {
it.remove();
}
}
}
}
/**
* Transform the collection by applying a Transformer to each element.
* <p/>
* If the input collection or transformer is null, there is no change made.
* <p/>
* This routine is best for Lists, for which set() is used to do the
* transformations "in place." For other Collections, clear() and addAll()
* are used to replace elements.
* <p/>
* If the input collection controls its input, such as a Set, and the
* Transformer creates duplicates (or are otherwise invalid), the collection
* may reduce in size due to calling this method.
*
* @param collection
* the collection to get the input from, may be null
* @param transformer
* the transformer to perform, may be null
*/
public static <E> void transform(Collection<E> collection,
Transformer<? super E, ? extends E> transformer) {
if (collection != null && transformer != null) {
if (collection instanceof List) {
List<E> list = (List<E>) collection;
for (ListIterator<E> it = list.listIterator(); it.hasNext();) {
it.set(transformer.transform(it.next()));
}
} else {
Collection<E> resultCollection = collect(collection,
transformer);
collection.clear();
collection.addAll(resultCollection);
}
}
}
/**
* Counts the number of elements in the input collection that match the
* predicate.
* <p/>
* A <code>null</code> collection or predicate matches no elements.
*
* @param inputIterable
* the collection to get the input from, may be null
* @param predicate
* the predicate to use, may be null
* @return the number of matches for the predicate in the collection
*/
public static <E> int countMatches(Iterable<E> inputIterable,
Predicate<? super E> predicate) {
int count = 0;
if (inputIterable != null && predicate != null) {
for (Iterator<E> it = inputIterable.iterator(); it.hasNext();) {
if (predicate.evaluate(it.next())) {
count++;
}
}
}
return count;
}
/**
* Answers true if a predicate is true for at least one element of a
* iterable.
* <p/>
* A <code>null</code> iterable or predicate returns false.
*
* @param iterable
* the iterable to get the input from, may be null
* @param predicate
* the predicate to use, may be null
* @return true if at least one element of the iterable matches the
* predicate
*/
public static <E> boolean exists(Iterable<E> iterable,
Predicate<? super E> predicate) {
if (iterable != null && predicate != null) {
for (Iterator<E> it = iterable.iterator(); it.hasNext();) {
if (predicate.evaluate(it.next())) {
return true;
}
}
}
return false;
}
/**
* Selects all elements from input collection which match the given
* predicate into an output collection.
* <p/>
* A <code>null</code> predicate matches no elements.
*
* @param inputCollection
* the collection to get the input from, may not be null
* @param predicate
* the predicate to use, may be null
* @return the elements matching the predicate (new list)
* @throws NullPointerException
* if the input collection is null
*/
public static <E> Collection<E> select(Collection<E> inputCollection,
Predicate<? super E> predicate) {
return select(inputCollection, predicate,
new ArrayList<E>(inputCollection.size()));
}
/**
* Selects all elements from input collection which match the given
* predicate and adds them to outputCollection.
* <p/>
* If the input collection or predicate is null, there is no change to the
* output collection.
*
* @param inputCollection
* the collection to get the input from, may be null
* @param predicate
* the predicate to use, may be null
* @param outputCollection
* the collection to output into, may not be null
*/
public static <E, C extends Collection<? super E>> C select(
Iterable<E> inputCollection, Predicate<? super E> predicate,
C outputCollection) {
if (inputCollection != null && predicate != null) {
for (Iterator<E> iter = inputCollection.iterator(); iter
.hasNext();) {
E item = iter.next();
if (predicate.evaluate(item)) {
outputCollection.add(item);
}
}
}
return outputCollection;
}
/**
* Selects all elements from inputCollection which don't match the given
* predicate into an output collection.
* <p/>
* If the input predicate is <code>null</code>, the result is an empty list.
*
* @param inputCollection
* the collection to get the input from, may not be null
* @param predicate
* the predicate to use, may be null
* @return the elements <b>not</b> matching the predicate (new list)
* @throws NullPointerException
* if the input collection is null
*/
public static <E> Collection<E> selectRejected(
Collection<E> inputCollection, Predicate<? super E> predicate) {
ArrayList<E> answer = new ArrayList<E>(inputCollection.size());
selectRejected(inputCollection, predicate, answer);
return answer;
}
/**
* Selects all elements from inputIterable which don't match the given
* predicate and adds them to outputCollection.
* <p/>
* If the input predicate is <code>null</code>, no elements are added to
* <code>outputCollection</code>.
*
* @param inputIterable
* the collection to get the input from, may be null
* @param predicate
* the predicate to use, may be null
* @param outputCollection
* the collection to output into, may not be null
*/
public static <E> void selectRejected(Iterable<E> inputIterable,
Predicate<? super E> predicate,
Collection<? super E> outputCollection) {
if (inputIterable != null && predicate != null) {
for (Iterator<E> iter = inputIterable.iterator(); iter.hasNext();) {
E item = iter.next();
if (predicate.evaluate(item) == false) {
outputCollection.add(item);
}
}
}
}
/**
* Returns a new Collection consisting of the elements of inputCollection
* transformed by the given transformer.
* <p/>
* If the input transformer is null, the result is an empty list.
*
* @param inputCollection
* the collection to get the input from, may not be null
* @param transformer
* the transformer to use, may be null
* @return the transformed result (new list)
* @throws NullPointerException
* if the input collection is null
*/
public static <I, O> Collection<O> collect(Collection<I> inputCollection,
Transformer<? super I, ? extends O> transformer) {
ArrayList<O> answer = new ArrayList<O>(inputCollection.size());
collect(inputCollection, transformer, answer);
return answer;
}
/**
* Transforms all elements from the inputIterator with the given transformer
* and adds them to the outputCollection.
* <p/>
* If the input iterator or transformer is null, the result is an empty
* list.
*
* @param inputIterator
* the iterator to get the input from, may be null
* @param transformer
* the transformer to use, may be null
* @return the transformed result (new list)
*/
public static <I, O> Collection<O> collect(Iterator<I> inputIterator,
Transformer<? super I, ? extends O> transformer) {
ArrayList<O> answer = new ArrayList<O>();
collect(inputIterator, transformer, answer);
return answer;
}
/**
* Transforms all elements from inputCollection with the given transformer
* and adds them to the outputCollection.
* <p/>
* If the input collection or transformer is null, there is no change to the
* output collection.
*
* @param inputCollection
* the collection to get the input from, may be null
* @param transformer
* the transformer to use, may not be null
* @param outputCollection
* the collection to output into, may not be null
* @return the outputCollection with the transformed input added
* @throws NullPointerException
* if the output collection is null
*/
public static <I, O, C extends Collection<O>> C collect(
Iterable<I> inputCollection,
final Transformer<? super I, ? extends O> transformer,
final C outputCollection) {
if (inputCollection != null) {
return collect(inputCollection.iterator(), transformer,
outputCollection);
}
return outputCollection;
}
/**
* Transforms all elements from the inputIterator with the given transformer
* and adds them to the outputCollection.
* <p/>
* If the input iterator or transformer is null, there is no change to the
* output collection.
*
* @param inputIterator
* the iterator to get the input from, may be null
* @param transformer
* the transformer to use, may not be null
* @param outputCollection
* the collection to output into, may not be null
* @return the outputCollection with the transformed input added
* @throws NullPointerException
* if the output collection is null
*/
public static <I, O, C extends Collection<O>> C collect(
Iterator<I> inputIterator,
final Transformer<? super I, ? extends O> transformer,
final C outputCollection) {
if (inputIterator != null && transformer != null) {
while (inputIterator.hasNext()) {
I item = inputIterator.next();
O value = transformer.transform(item);
outputCollection.add(value);
}
}
return outputCollection;
}
/**
* Adds all elements in the iteration to the given collection.
*
* deprecated Replaced by {@link Collection#addAll(java.util.Collection<?
* extends E>)}
*
* @param collection
* the collection to add to
* @param iterator
* the iterator of elements to add, may not be null
* @throws NullPointerException
* if the collection or iterator is null
*/
public static <E> void addAll(Collection<E> collection,
Iterator<? extends E> iterator) {
while (iterator.hasNext()) {
collection.add(iterator.next());
}
}
/**
* Adds all elements in the enumeration to the given collection.
*
* deprecated Replaced by {@link Collection#addAll(java.util.Collection<?
* extends E>)}
*
* @param collection
* the collection to add to
* @param enumeration
* the enumeration of elements to add, may not be null
* @throws NullPointerException
* if the collection or enumeration is null
*/
public static <E> void addAll(Collection<E> collection,
Enumeration<? extends E> enumeration) {
while (enumeration.hasMoreElements()) {
collection.add(enumeration.nextElement());
}
}
/**
* Adds all elements in the array to the given collection.
*
* @param collection
* the collection to add to, may not be null
* @param elements
* the array of elements to add, may not be null
* @throws NullPointerException
* if the collection or array is null
*/
public static <E, T extends E> void addAll(Collection<E> collection,
T... elements) {
for (int i = 0, size = elements.length; i < size; i++) {
collection.add(elements[i]);
}
}
/**
* Given an Object, and an index, returns the nth value in the object.
* <ul>
* <li>If obj is a Map, returns the nth value from the <b>keySet</b>
* iterator, unless the Map contains an Integer key with integer value =
* idx, in which case the corresponding map entry value is returned. If idx
* exceeds the number of entries in the map, an empty Iterator is returned.
* <li>If obj is a List or an array, returns the nth value, throwing
* IndexOutOfBoundsException, ArrayIndexOutOfBoundsException, resp. if the
* nth value does not exist.
* <li>If obj is an iterator, enumeration or Collection, returns the nth
* value from the iterator, returning an empty Iterator (resp. Enumeration)
* if the nth value does not exist.
* <li>Returns the original obj if it is null or not a Collection or
* Iterator.
* </ul>
*
* @param obj
* the object to get an index of, may be null
* @param idx
* the index to get
* @throws IndexOutOfBoundsException
* @throws ArrayIndexOutOfBoundsException
* deprecated use {@link #get(Object, int)} instead. Will be removed in
* v4.0
*/
public static Object index(Object obj, int idx) {
return index(obj, Integer.valueOf(idx));
}
/**
* Given an Object, and a key (index), returns the value associated with
* that key in the Object. The following checks are made:
* <ul>
* <li>If obj is a Map, use the index as a key to get a value. If no match
* continue.
* <li>Check key is an Integer. If not, return the object passed in.
* <li>If obj is a Map, get the nth value from the <b>keySet</b> iterator.
* If the Map has fewer than n entries, return an empty Iterator.
* <li>If obj is a List or an array, get the nth value, throwing
* IndexOutOfBoundsException, ArrayIndexOutOfBoundsException, resp. if the
* nth value does not exist.
* <li>If obj is an iterator, enumeration or Collection, get the nth value
* from the iterator, returning an empty Iterator (resp. Enumeration) if the
* nth value does not exist.
* <li>Return the original obj.
* </ul>
*
* @param obj
* the object to get an index of
* @param index
* the index to get
* @return the object at the specified index
* @throws IndexOutOfBoundsException
* @throws ArrayIndexOutOfBoundsException
* deprecated use {@link #get(Object, int)} instead. Will be removed in
* v4.0
*/
public static Object index(Object obj, Object index) {
if (obj instanceof Map) {
Map map = (Map) obj;
if (map.containsKey(index)) {
return map.get(index);
}
}
int idx = -1;
if (index instanceof Integer) {
idx = ((Integer) index).intValue();
}
if (idx < 0) {
return obj;
} else if (obj instanceof Map) {
Map map = (Map) obj;
Iterator iterator = map.keySet().iterator();
return index(iterator, idx);
} else if (obj instanceof List) {
return ((List) obj).get(idx);
} else if (obj instanceof Object[]) {
return ((Object[]) obj)[idx];
} else if (obj instanceof Enumeration) {
Enumeration it = (Enumeration) obj;
while (it.hasMoreElements()) {
idx--;
if (idx == -1) {
return it.nextElement();
}
it.nextElement();
}
} else if (obj instanceof Iterator) {
return index((Iterator) obj, idx);
} else if (obj instanceof Collection) {
Iterator iterator = ((Collection) obj).iterator();
return index(iterator, idx);
}
return obj;
}
private static Object index(Iterator iterator, int idx) {
while (iterator.hasNext()) {
idx--;
if (idx == -1) {
return iterator.next();
}
iterator.next();
}
return iterator;
}
/**
* Returns the <code>index</code>-th value in <code>object</code>, throwing
* <code>IndexOutOfBoundsException</code> if there is no such element or
* <code>IllegalArgumentException</code> if <code>object</code> is not an
* instance of one of the supported types.
* <p/>
* The supported types, and associated semantics are:
* <ul>
* <li>Map -- the value returned is the <code>Map.Entry</code> in position
* <code>index</code> in the map's <code>entrySet</code> iterator, if there
* is such an entry.</li>
* <li>List -- this method is equivalent to the list's get method.</li>
* <li>Array -- the <code>index</code>-th array entry is returned, if there
* is such an entry; otherwise an <code>IndexOutOfBoundsException</code> is
* thrown.</li>
* <li>Collection -- the value returned is the <code>index</code>-th object
* returned by the collection's default iterator, if there is such an
* element.</li>
* <li>Iterator or Enumeration -- the value returned is the
* <code>index</code>-th object in the Iterator/Enumeration, if there is
* such an element. The Iterator/Enumeration is advanced to
* <code>index</code> (or to the end, if <code>index</code> exceeds the
* number of entries) as a side effect of this method.</li>
* </ul>
*
* @param object
* the object to get a value from
* @param index
* the index to get
* @return the object at the specified index
* @throws IndexOutOfBoundsException
* if the index is invalid
* @throws IllegalArgumentException
* if the object type is invalid
*/
public static Object get(Object object, int index) {
/*
* if (index < 0) { throw new IndexOutOfBoundsException(
* "Index cannot be negative: " + index); } if (object instanceof Map) {
* Map map = (Map) object; Iterator iterator =
* map.entrySet().iterator(); return get(iterator, index); } else if
* (object instanceof List) { return ((List) object).get(index); } else
* if (object instanceof Object[]) { return ((Object[]) object)[index];
* } else if (object instanceof Iterator) { Iterator it = (Iterator)
* object; while (it.hasNext()) { index--; if (index == -1) { return
* it.next(); } else { it.next(); } } throw new
* IndexOutOfBoundsException("Entry does not exist: " + index); } else
* if (object instanceof Collection) { Iterator iterator = ((Collection)
* object).iterator(); return get(iterator, index); } else if (object
* instanceof Enumeration) { Enumeration it = (Enumeration) object;
* while (it.hasMoreElements()) { index--; if (index == -1) { return
* it.nextElement(); } else { it.nextElement(); } } throw new
* IndexOutOfBoundsException("Entry does not exist: " + index); } else
* if (object == null) { throw new IllegalArgumentException(
* "Unsupported object type: null"); } else { try { return
* Array.get(object, index); } catch (IllegalArgumentException ex) {
* throw new IllegalArgumentException("Unsupported object type: " +
* object.getClass().getName()); } }
*/
throw new RuntimeException(
"java.lang.reflect.Array is not available in GWT");
}
/**
* Gets the size of the collection/iterator specified.
* <p/>
* This method can handles objects as follows
* <ul>
* <li>Collection - the collection size
* <li>Map - the map size
* <li>Array - the array size
* <li>Iterator - the number of elements remaining in the iterator
* <li>Enumeration - the number of elements remaining in the enumeration
* </ul>
*
* @param object
* the object to get the size of
* @return the size of the specified collection
* @throws IllegalArgumentException
* thrown if object is not recognised or null
* @since Commons Collections 3.1
*/
public static int size(Object object) {
throw new RuntimeException(
"java.lang.reflect.Array is not available in GWT");
/*
* int total = 0; if (object instanceof Map) { total = ((Map)
* object).size(); } else if (object instanceof Collection) { total =
* ((Collection) object).size(); } else if (object instanceof Object[])
* { total = ((Object[]) object).length; } else if (object instanceof
* Iterator) { Iterator it = (Iterator) object; while (it.hasNext()) {
* total++; it.next(); } } else if (object instanceof Enumeration) {
* Enumeration it = (Enumeration) object; while (it.hasMoreElements()) {
* total++; it.nextElement(); } } else if (object == null) { throw new
* IllegalArgumentException("Unsupported object type: null"); } else {
* try { total = Array.getLength(object); } catch
* (IllegalArgumentException ex) { throw new IllegalArgumentException(
* "Unsupported object type: " + object.getClass().getName()); } }
* return total;
*/
}
/**
* Reverses the order of the given array.
*
* @param array
* the array to reverse
*/
public static void reverseArray(Object[] array) {
int i = 0;
int j = array.length - 1;
Object tmp;
while (j > i) {
tmp = array[j];
array[j] = array[i];
array[i] = tmp;
j--;
i++;
}
}
private static final int getFreq(final Object obj, final Map freqMap) {
Integer count = (Integer) freqMap.get(obj);
if (count != null) {
return count.intValue();
}
return 0;
}
/**
* Returns true if no more elements can be added to the Collection.
* <p/>
* This method uses the {@link BoundedCollection} interface to determine the
* full status. If the collection does not implement this interface then
* false is returned.
* <p/>
* The collection does not have to implement this interface directly. If the
* collection has been decorated using the decorators subpackage then these
* will be removed to access the BoundedCollection.
*
* @param coll
* the collection to check
* @return true if the BoundedCollection is full
* @throws NullPointerException
* if the collection is null
*/
// public static boolean isFull(Collection coll) {
// if (coll == null) {
// throw new NullPointerException("The collection must not be null");
// }
// if (coll instanceof BoundedCollection) {
// return ((BoundedCollection) coll).isFull();
// }
// try {
// BoundedCollection bcoll =
// UnmodifiableBoundedCollection.decorateUsing(coll);
// return bcoll.isFull();
//
// } catch (IllegalArgumentException ex) {
// return false;
// }
// }
/**
* Get the maximum number of elements that the Collection can contain.
* <p/>
* This method uses the {@link BoundedCollection} interface to determine the
* maximum size. If the collection does not implement this interface then -1
* is returned.
* <p/>
* The collection does not have to implement this interface directly. If the
* collection has been decorated using the decorators subpackage then these
* will be removed to access the BoundedCollection.
*
* @param coll
* the collection to check
* @return the maximum size of the BoundedCollection, -1 if no maximum size
* @throws NullPointerException
* if the collection is null
*/
// public static int maxSize(Collection coll) {
// if (coll == null) {
// throw new NullPointerException("The collection must not be null");
// }
// if (coll instanceof BoundedCollection) {
// return ((BoundedCollection) coll).maxSize();
// }
// try {
// BoundedCollection bcoll =
// UnmodifiableBoundedCollection.decorateUsing(coll);
// return bcoll.maxSize();
//
// } catch (IllegalArgumentException ex) {
// return -1;
// }
// }
// -----------------------------------------------------------------------
/**
* Returns a synchronized collection backed by the given collection.
* <p/>
* You must manually synchronize on the returned buffer's iterator to avoid
* non-deterministic behavior:
* <p/>
*
* <pre>
* Collection c = CollectionUtils.synchronizedCollection(myCollection);
* synchronized (c) {
* Iterator i = c.iterator();
* while (i.hasNext()) {
* process(i.next());
* }
* }
* </pre>
* <p/>
* This method uses the implementation in the decorators subpackage.
*
* @param collection
* the collection to synchronize, must not be null
* @return a synchronized collection backed by the given collection
* @throws IllegalArgumentException
* if the collection is null
*/
// public static <E> Collection<E> synchronizedCollection(Collection<E>
// collection) {
// return SynchronizedCollection.decorate(collection);
// }
/**
* Returns an unmodifiable collection backed by the given collection.
* <p/>
* This method uses the implementation in the decorators subpackage.
*
* @param collection
* the collection to make unmodifiable, must not be null
* @return an unmodifiable collection backed by the given collection
* @throws IllegalArgumentException
* if the collection is null
*/
public static <E> Collection<E> unmodifiableCollection(
Collection<E> collection) {
return UnmodifiableCollection.decorate(collection);
}
/**
* Returns a predicated (validating) collection backed by the given
* collection.
* <p/>
* Only objects that pass the test in the given predicate can be added to
* the collection. Trying to add an invalid object results in an
* IllegalArgumentException. It is important not to use the original
* collection after invoking this method, as it is a backdoor for adding
* invalid objects.
*
* @param collection
* the collection to predicate, must not be null
* @param predicate
* the predicate for the collection, must not be null
* @return a predicated collection backed by the given collection
* @throws IllegalArgumentException
* if the Collection is null
*/
// public static <E> Collection<E> predicatedCollection(Collection<E>
// collection, Predicate<? super E> predicate) {
// return PredicatedCollection.decorate(collection, predicate);
// }
/**
* Returns a typed collection backed by the given collection.
* <p/>
* Only objects of the specified type can be added to the collection.
*
* @param collection
* the collection to limit to a specific type, must not be null
* @param type
* the type of objects which may be added to the collection
* @return a typed collection backed by the specified collection
* deprecated Obsoleted by Java 1.5 Generics.
*/
// public static <E> Collection<E> typedCollection(Collection<E> collection,
// Class<E> type) {
// return TypedCollection.decorate(collection, type);
// }
/**
* Returns a transformed bag backed by the given collection.
* <p/>
* Each object is passed through the transformer as it is added to the
* Collection. It is important not to use the original collection after
* invoking this method, as it is a backdoor for adding untransformed
* objects.
*
* @param collection
* the collection to predicate, must not be null
* @param transformer
* the transformer for the collection, must not be null
* @return a transformed collection backed by the given collection
* @throws IllegalArgumentException
* if the Collection or Transformer is null
*/
// public static <I,O> Collection<O> transformedCollection(Collection<I>
// collection, Transformer<? super I, ? extends O> transformer) {
// return TransformedCollection.decorate(collection, transformer);
// }
}