at.molindo.esi4j.rebuild.util.IteratorRebuildSession.java Source code

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Here is the source code for at.molindo.esi4j.rebuild.util.IteratorRebuildSession.java

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/**
 * Copyright 2010 Molindo GmbH
 *
 * 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 at.molindo.esi4j.rebuild.util;

import java.util.Iterator;
import java.util.List;

import at.molindo.esi4j.rebuild.Esi4JRebuildSession;

import com.google.common.collect.Lists;

/**
 * {@link Esi4JRebuildSession} implementation using a simple {@link Iterator}
 */
public class IteratorRebuildSession implements Esi4JRebuildSession {

    private final Class<?> _type;
    private Iterator<?> _iterator;
    private final boolean _ordered;

    public IteratorRebuildSession(Class<?> type, Iterator<?> iterator, boolean ordered) {
        if (type == null) {
            throw new NullPointerException("type");
        }
        if (iterator == null) {
            throw new NullPointerException("iterator");
        }
        _type = type;
        _iterator = iterator;
        _ordered = ordered;
    }

    @Override
    public Class<?> getType() {
        return _type;
    }

    @Override
    public boolean isOrdered() {
        return _ordered;
    }

    @Override
    public List<?> getNext(int batchSize) {
        if (_iterator == null) {
            throw new IllegalStateException("already closed");
        }

        List<Object> list = Lists.newArrayListWithCapacity(batchSize);
        while (list.size() < batchSize && _iterator.hasNext()) {
            list.add(_iterator.next());
        }

        return list;
    }

    @Override
    public Object getMetadata() {
        return null;
    }

    @Override
    public void close() {
        _iterator = null;
    }

}