Android Open Source - android_rss_reader Feed Item Cache

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License

The source code is released under:

Apache License

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Java Source Code

/***********************************************************************************************************************
 * ==========================================
 */*w  w w .j a  v  a 2  s  .co m*/
 * Copyright (C) 2013 by Paul Oremland
 * http://www.linkedin.com/in/pauloremland
 * https://github.com/poremland
 *
 ***********************************************************************************************************************
 *
 * 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 net.oremland.rss.reader.helpers;

import java.util.*;

import net.oremland.rss.reader.models.*;

public class FeedItemCache
{
  private final static int expirationMilliseconds = 1000 * (15 * 60);
  private ArrayList<CacheItem> items = new ArrayList<CacheItem>();

  public FeedItemCache()
  {
  }

  protected int expireIfOlderThanMilliseconds()
  {
    return expirationMilliseconds;
  }

  public int size()
  {
    return this.asList().size();
  }

  
  public synchronized void add(FeedItem item)
  {
    if(!items.contains(new CacheItem(item)))
    {
      items.add(new CacheItem(item));
    }
  }

  public synchronized List<FeedItem> asList()
  {
    ArrayList<FeedItem> list = new ArrayList<FeedItem>();
    ArrayList<CacheItem> purged = new ArrayList<CacheItem>();
    for(CacheItem item : items)
    {
      if(!this.isExpired(item))
      {
        purged.add(item);
        list.add(item.item);
      }
    }
    items = purged;
    return list;
  }

  private boolean isExpired(CacheItem item)
  {
    long diff = new Date().getTime() - item.cachedAt.getTime();
    return diff >= this.expireIfOlderThanMilliseconds();
  }

  private class CacheItem
  {
    public final Date cachedAt = new Date();
    public final FeedItem item;

    public CacheItem(FeedItem item)
    {
      this.item = item;
    }

    @Override
    public boolean equals(Object obj)
    {
      if(obj == null)
      {
        return false;
      }

      if(obj instanceof CacheItem)
      {
        return ((CacheItem)obj).item.equals(this.item);
      }

      return false;
    }
  }
}

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