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A light weight and high performance Java caching library. Android and Java 6 compatible. This artifact contains the official API of cache2k.

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package org.cache2k.config;

/*
 * #%L
 * cache2k API
 * %%
 * Copyright (C) 2000 - 2021 headissue GmbH, Munich
 * %%
 * 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.
 * #L%
 */

import org.cache2k.annotation.Nullable;

import java.util.AbstractCollection;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

/**
 * Container for configuration objects. The container preserves the order of the sections
 * and checks that one type is only added once.
 *
 * @author Jens Wilke
 * @see ConfigWithSections
 */
public class SectionContainer extends AbstractCollection
  implements Collection {

  private final Map, ConfigSection> class2section = new HashMap<>();

  /**
   * Add a new configuration section to the container.
   *
   * @throws IllegalArgumentException if same type is already present and a singleton
   * @return always {@code true}
   */
  @Override
  public boolean add(ConfigSection section) {
    if (getSection(section.getClass()) !=  null) {
      throw new IllegalArgumentException(
        "Section of same type already inserted: " + section.getClass().getName());
    }
    class2section.put(section.getClass(), section);
    return true;
  }

  /**
   * Retrieve a single section from the container.
   */
  public  T getSection(Class sectionType, T defaultFallback) {
    ConfigSection section = class2section.get(sectionType);
    return section != null ? sectionType.cast(section) : defaultFallback;
  }

  public @Nullable  T getSection(Class sectionType) {
    ConfigSection section = class2section.get(sectionType);
    return sectionType.cast(section);
  }

  @Override
  public Iterator iterator() {
    return class2section.values().iterator();
  }

  @Override
  public int size() {
    return class2section.size();
  }

  public String toString() {
    return getClass().getSimpleName() + class2section.values().toString();
  }

}