bval-jsr/src/main/java/org/apache/bval/util/CollectionSet.java

/*
 * 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.bval.util;

import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.Set;

/**
 * Unmodifiable {@link Set} backed by a {@link Collection} obeying {@link Set} semantics.
 *
 * @param <E>
 */
public class CollectionSet<E> implements Set<E> {
    private final Collection<E> wrapped;

    public CollectionSet(Collection<? extends E> wrapped) {
        super();
        this.wrapped = Collections.unmodifiableCollection(Validate.notNull(wrapped));
        Validate.isTrue(wrapped.stream().distinct().count() == wrapped.size(), "Collection values are not distinct");
    }

    @Override
    public int size() {
        return wrapped.size();
    }

    @Override
    public boolean isEmpty() {
        return wrapped.isEmpty();
    }

    @Override
    public boolean contains(Object o) {
        return wrapped.contains(o);
    }

    @Override
    public Iterator<E> iterator() {
        return wrapped.iterator();
    }

    @Override
    public Object[] toArray() {
        return wrapped.toArray();
    }

    @Override
    public <T> T[] toArray(T[] a) {
        return wrapped.toArray(a);
    }

    @Override
    public boolean add(E e) {
        throw new UnsupportedOperationException();
    }

    @Override
    public boolean remove(Object o) {
        throw new UnsupportedOperationException();
    }

    @Override
    public boolean containsAll(Collection<?> c) {
        return wrapped.containsAll(c);
    }

    @Override
    public boolean addAll(Collection<? extends E> c) {
        throw new UnsupportedOperationException();
    }

    @Override
    public boolean retainAll(Collection<?> c) {
        throw new UnsupportedOperationException();
    }

    @Override
    public boolean removeAll(Collection<?> c) {
        throw new UnsupportedOperationException();
    }

    @Override
    public void clear() {
        throw new UnsupportedOperationException();
    }
}