org.solovyev.common.collections.multimap.ObjectsAddedUpdater.java Source code

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Here is the source code for org.solovyev.common.collections.multimap.ObjectsAddedUpdater.java

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/*
 * Copyright 2013 serso aka se.solovyev
 *
 * 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.solovyev.common.collections.multimap;

import java.util.Collection;
import java.util.List;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;

import com.google.common.collect.Iterables;

public final class ObjectsAddedUpdater<V> implements ThreadSafeMultimap.ListUpdater<V> {

    @Nonnull
    private final Collection<V> newObjects;

    public ObjectsAddedUpdater(@Nonnull Collection<V> newObjects) {
        this.newObjects = newObjects;
    }

    @Nullable
    @Override
    public List<V> update(@Nonnull List<V> values) {
        if (values == ThreadSafeMultimap.NO_VALUE) {
            return null;
        } else {
            List<V> result = null;
            for (V newObject : newObjects) {
                if (!Iterables.contains(values, newObject)) {
                    if (result == null) {
                        result = ThreadSafeMultimap.copy(values);
                    }
                    result.add(newObject);
                }
            }
            return result;
        }
    }
}