uk.gov.gchq.gaffer.commonutil.iterable.EmptyClosableIterable Maven / Gradle / Ivy

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/*
 * Copyright 2016-2019 Crown Copyright
 *
 * 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 uk.gov.gchq.gaffer.commonutil.iterable;

import org.apache.commons.lang3.builder.EqualsBuilder;
import org.apache.commons.lang3.builder.HashCodeBuilder;

/**
 * An {@code EmptyCloseableIterable} is an {@link java.lang.Iterable} which is backed by a
 * {@link EmptyCloseableIterator}, and contains no objects.
 *
 * This is useful when a {@link java.lang.Iterable} is required, but there is no data present.
 *
 * @param  the type of items in the iterable.
 */
public class EmptyClosableIterable implements CloseableIterable {

    @Override
    public void close() {
    }

    @Override
    public CloseableIterator iterator() {
        return new EmptyCloseableIterator<>();
    }

    @Override
    public boolean equals(final Object obj) {
        if (this == obj) {
            return true;
        }

        if (obj == null || getClass() != obj.getClass()) {
            return false;
        }

        final EmptyClosableIterable that = (EmptyClosableIterable) obj;

        return new EqualsBuilder()
                .isEquals();
    }

    @Override
    public int hashCode() {
        return new HashCodeBuilder(17, 37)
                .toHashCode();
    }
}