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Commons Collections example source code file (UnmodifiableEntrySet.java)

This example Commons Collections source code file (UnmodifiableEntrySet.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Commons Collections tags/keywords

abstractiteratordecorator, abstractmapentrydecorator, abstractsetdecorator, iterator, object, object, reflection, unmodifiable, unmodifiableentry, unmodifiableentryset, unmodifiableentryset, unmodifiableentrysetiterator, unmodifiableentrysetiterator, unsupportedoperationexception, unsupportedoperationexception, util

The Commons Collections UnmodifiableEntrySet.java source code

/*
 *  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.map;

import java.lang.reflect.Array;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import org.apache.commons.collections.Unmodifiable;
import org.apache.commons.collections.iterators.AbstractIteratorDecorator;
import org.apache.commons.collections.keyvalue.AbstractMapEntryDecorator;
import org.apache.commons.collections.set.AbstractSetDecorator;

/**
 * Decorates a map entry <code>Set to ensure it can't be altered.
 *
 * @since Commons Collections 3.0
 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
 * 
 * @author Stephen Colebourne
 */
public final class UnmodifiableEntrySet
        extends AbstractSetDecorator implements Unmodifiable {

    /**
     * Factory method to create an unmodifiable set of Map Entry objects.
     * 
     * @param set  the set to decorate, must not be null
     * @throws IllegalArgumentException if set is null
     */
    public static Set decorate(Set set) {
        if (set instanceof Unmodifiable) {
            return set;
        }
        return new UnmodifiableEntrySet(set);
    }

    //-----------------------------------------------------------------------
    /**
     * Constructor that wraps (not copies).
     * 
     * @param set  the set to decorate, must not be null
     * @throws IllegalArgumentException if set is null
     */
    private UnmodifiableEntrySet(Set set) {
        super(set);
    }

    //-----------------------------------------------------------------------
    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 Iterator iterator() {
        return new UnmodifiableEntrySetIterator(collection.iterator());
    }
    
    public Object[] toArray() {
        Object[] array = collection.toArray();
        for (int i = 0; i < array.length; i++) {
            array[i] = new UnmodifiableEntry((Map.Entry) array[i]);
        }
        return array;
    }
    
    public Object[] toArray(Object array[]) {
        Object[] result = array;
        if (array.length > 0) {
            // we must create a new array to handle multi-threaded situations
            // where another thread could access data before we decorate it
            result = (Object[]) Array.newInstance(array.getClass().getComponentType(), 0);
        }
        result = collection.toArray(result);
        for (int i = 0; i < result.length; i++) {
            result[i] = new UnmodifiableEntry((Map.Entry) result[i]);
        }

        // check to see if result should be returned straight
        if (result.length > array.length) {
            return result;
        }

        // copy back into input array to fulfil the method contract
        System.arraycopy(result, 0, array, 0, result.length);
        if (array.length > result.length) {
            array[result.length] = null;
        }
        return array;
    }
    
    //-----------------------------------------------------------------------
    /**
     * Implementation of an entry set iterator.
     */
    final static class UnmodifiableEntrySetIterator extends AbstractIteratorDecorator {
        
        protected UnmodifiableEntrySetIterator(Iterator iterator) {
            super(iterator);
        }
        
        public Object next() {
            Map.Entry entry = (Map.Entry) iterator.next();
            return new UnmodifiableEntry(entry);
        }
        
        public void remove() {
            throw new UnsupportedOperationException();
        }
    }

    //-----------------------------------------------------------------------
    /**
     * Implementation of a map entry that is unmodifiable.
     */
    final static class UnmodifiableEntry extends AbstractMapEntryDecorator {

        protected UnmodifiableEntry(Map.Entry entry) {
            super(entry);
        }

        public Object setValue(Object obj) {
            throw new UnsupportedOperationException();
        }
    }

}

Other Commons Collections examples (source code examples)

Here is a short list of links related to this Commons Collections UnmodifiableEntrySet.java source code file:

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