最少使用的缓存

import java.util.LinkedHashMap;

import java.util.Map;
/** nowjava.com - 时  代  Java 提供 **/

class LFULeastFrequentUsedCache {


  class CacheEntry {

    private String data;

    private int frequency;


    // default constructor

    private CacheEntry() {

    }


    public String getData() {

      return data;

    }

    /*来自 
     N o w  J a v a  .   c o m*/

    public void setData(String data) {

      this.data = data;

    }


    public int getFrequency() {

      return frequency;

    }


    public void setFrequency(int frequency) {

      this.frequency = frequency;

    }


  }


  private static int initialCapacity;


  private static LinkedHashMap<Integer, CacheEntry> cacheMap = new LinkedHashMap<Integer, CacheEntry>();

  /*

   * LinkedHashMap is used since it has features of both HashMap and LinkedList.

   * Thus, we can get an entry in O(1) and we can iterate over it easily.

   */


  public LFULeastFrequentUsedCache(int initialCapacity) {

    this.initialCapacity = initialCapacity;

  }


  public void addCacheEntry(int key, String data) {

    if (!isFull()) {

      CacheEntry temp = new CacheEntry();

      temp.setData(data);

      temp.setFrequency(0);


      cacheMap.put(key, temp);

    } else {

      int entryKeyToBeRemoved = getLFUKey();

      cacheMap.remove(entryKeyToBeRemoved);


      CacheEntry temp = new CacheEntry();

      temp.setData(data);

      temp.setFrequency(0);


      cacheMap.put(key, temp);

    }

  }


  public int getLFUKey() {

    int key = 0;

    int minFreq = Integer.MAX_VALUE;


    for (Map.Entry<Integer, CacheEntry> entry : cacheMap.entrySet()) {

      if (minFreq > entry.getValue().frequency) {

        key = entry.getKey();

        minFreq = entry.getValue().frequency;

      }

    }


    return key;

  }


  public String getCacheEntry(int key) {

    if (cacheMap.containsKey(key)) // cache hit

    {

      CacheEntry temp = cacheMap.get(key);

      temp.frequency++;

      cacheMap.put(key, temp);

      return temp.data;

    }

    return null; // cache miss

  }


  public static boolean isFull() {

    if (cacheMap.size() == initialCapacity)

      return true;


    return false;

  }



}

public class Main{

  public static void main(String args[]) {


    LFULeastFrequentUsedCache lfu = new LFULeastFrequentUsedCache(4);


    lfu.addCacheEntry(1,