org.apache.commons.collections.bag.UnmodifiableBag 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.bag;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.Collection;
import java.util.Iterator;
import java.util.Set;
import org.apache.commons.collections.Bag;
import org.apache.commons.collections.Unmodifiable;
import org.apache.commons.collections.iterators.UnmodifiableIterator;
import org.apache.commons.collections.set.UnmodifiableSet;
/**
* Decorates another Bag to ensure it can't be altered.
*
* This class is Serializable from Commons Collections 3.1.
*
* @since Commons Collections 3.0
* @version $Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $
*
* @author Stephen Colebourne
*/
public final class UnmodifiableBag
extends AbstractBagDecorator implements Unmodifiable, Serializable {
/** Serialization version */
private static final long serialVersionUID = -1873799975157099624L;
/**
* Factory method to create an unmodifiable bag.
*
* If the bag passed in is already unmodifiable, it is returned.
*
* @param bag the bag to decorate, must not be null
* @return an unmodifiable Bag
* @throws IllegalArgumentException if bag is null
*/
public static Bag decorate(Bag bag) {
if (bag instanceof Unmodifiable) {
return bag;
}
return new UnmodifiableBag(bag);
}
//-----------------------------------------------------------------------
/**
* Constructor that wraps (not copies).
*
* @param bag the bag to decorate, must not be null
* @throws IllegalArgumentException if bag is null
*/
private UnmodifiableBag(Bag bag) {
super(bag);
}
//-----------------------------------------------------------------------
/**
* Write the collection out using a custom routine.
*
* @param out the output stream
* @throws IOException
*/
private void writeObject(ObjectOutputStream out) throws IOException {
out.defaultWriteObject();
out.writeObject(collection);
}
/**
* Read the collection in using a custom routine.
*
* @param in the input stream
* @throws IOException
* @throws ClassNotFoundException
*/
private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
in.defaultReadObject();
collection = (Collection) in.readObject();
}
//-----------------------------------------------------------------------
public Iterator iterator() {
return UnmodifiableIterator.decorate(getCollection().iterator());
}
public boolean add(Object object) {
throw new UnsupportedOperationException();
}
public boolean addAll(Collection coll) {
throw new UnsupportedOperationException();
}
public void clear() {
throw new UnsupportedOperationException();
}
public boolean remove(Object object) {
throw new UnsupportedOperationException();
}
public boolean removeAll(Collection coll) {
throw new UnsupportedOperationException();
}
public boolean retainAll(Collection coll) {
throw new UnsupportedOperationException();
}
//-----------------------------------------------------------------------
public boolean add(Object object, int count) {
throw new UnsupportedOperationException();
}
public boolean remove(Object object, int count) {
throw new UnsupportedOperationException();
}
public Set uniqueSet() {
Set set = getBag().uniqueSet();
return UnmodifiableSet.decorate(set);
}
}