com.groupbyinc.common.apache.commons.collections4.collection.UnmodifiableBoundedCollection 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.collections4.collection;
import java.util.Collection;
import java.util.Iterator;
import org.apache.commons.collections4.BoundedCollection;
import org.apache.commons.collections4.Unmodifiable;
import org.apache.commons.collections4.iterators.UnmodifiableIterator;
/**
* {@link UnmodifiableBoundedCollection} decorates another
* {@link BoundedCollection} to ensure it can't be altered.
*
* If a BoundedCollection is first wrapped in some other collection decorator,
* such as synchronized or predicated, the BoundedCollection methods are no
* longer accessible.
* The factory on this class will attempt to retrieve the bounded nature by
* examining the package scope variables.
*
* This class is Serializable from Commons Collections 3.1.
*
* Attempts to modify it will result in an UnsupportedOperationException.
*
* @since 3.0
* @version $Id: UnmodifiableBoundedCollection.java 1686855 2015-06-22 13:00:27Z tn $
*/
public final class UnmodifiableBoundedCollection extends AbstractCollectionDecorator
implements BoundedCollection, Unmodifiable {
/** Serialization version */
private static final long serialVersionUID = -7112672385450340330L;
/**
* Factory method to create an unmodifiable bounded collection.
*
* @param the type of the elements in the collection
* @param coll the BoundedCollection to decorate, must not be null
* @return a new unmodifiable bounded collection
* @throws NullPointerException if {@code coll} is {@code null}
* @since 4.0
*/
public static BoundedCollection unmodifiableBoundedCollection(final BoundedCollection coll) {
if (coll instanceof Unmodifiable) {
@SuppressWarnings("unchecked") // safe to upcast
final BoundedCollection tmpColl = (BoundedCollection) coll;
return tmpColl;
}
return new UnmodifiableBoundedCollection(coll);
}
/**
* Factory method to create an unmodifiable bounded collection.
*
* This method is capable of drilling down through up to 1000 other decorators
* to find a suitable BoundedCollection.
*
* @param the type of the elements in the collection
* @param coll the BoundedCollection to decorate, must not be null
* @return a new unmodifiable bounded collection
* @throws NullPointerException if coll is null
* @throws IllegalArgumentException if coll is not a {@code BoundedCollection}
* @since 4.0
*/
@SuppressWarnings("unchecked")
public static BoundedCollection unmodifiableBoundedCollection(Collection coll) {
if (coll == null) {
throw new NullPointerException("Collection must not be null.");
}
// handle decorators
for (int i = 0; i < 1000; i++) { // counter to prevent infinite looping
if (coll instanceof BoundedCollection) {
break; // normal loop exit
}
if (coll instanceof AbstractCollectionDecorator) {
coll = ((AbstractCollectionDecorator) coll).decorated();
} else if (coll instanceof SynchronizedCollection) {
coll = ((SynchronizedCollection) coll).decorated();
}
}
if (coll instanceof BoundedCollection == false) {
throw new IllegalArgumentException("Collection is not a bounded collection.");
}
return new UnmodifiableBoundedCollection((BoundedCollection) coll);
}
/**
* Constructor that wraps (not copies).
*
* @param coll the collection to decorate, must not be null
* @throws NullPointerException if coll is null
*/
@SuppressWarnings("unchecked") // safe to upcast
private UnmodifiableBoundedCollection(final BoundedCollection coll) {
super((BoundedCollection) coll);
}
//-----------------------------------------------------------------------
@Override
public Iterator iterator() {
return UnmodifiableIterator.unmodifiableIterator(decorated().iterator());
}
@Override
public boolean add(final E object) {
throw new UnsupportedOperationException();
}
@Override
public boolean addAll(final Collection coll) {
throw new UnsupportedOperationException();
}
@Override
public void clear() {
throw new UnsupportedOperationException();
}
@Override
public boolean remove(final Object object) {
throw new UnsupportedOperationException();
}
@Override
public boolean removeAll(final Collection coll) {
throw new UnsupportedOperationException();
}
@Override
public boolean retainAll(final Collection coll) {
throw new UnsupportedOperationException();
}
//-----------------------------------------------------------------------
@Override
public boolean isFull() {
return decorated().isFull();
}
@Override
public int maxSize() {
return decorated().maxSize();
}
@Override
protected BoundedCollection decorated() {
return (BoundedCollection) super.decorated();
}
}