• 基于LinkedHashMap实现LRUCache

public class LRUCache2
    
      extends LinkedHashMap {  private int size;  private HashMap
     
       map;  public LRUCache2(int size) {    this.size = size;    this.map =        new LinkedHashMap
      
       (size, 0.75f, true) {          @Override          protected boolean removeEldestEntry(Map.Entry eldest) {            return size() > size;          }        };  }  public V getValue(K key) {    if (this.map.containsKey(key)) {      return this.map.get(key);    } else {      return null;    }  }  public void set(K key, V value) {    this.map.put(key, value);  }  public void print() {    this.map.forEach((k, v) -> System.out.println(k + "\t" + v));  }}
      
     
    

• 测试案例

public class LRUCacheDemo {  public static void main(String[] args) {    LRUCache2
    
      cache = new LRUCache2(3);    cache.set(1, "One");    cache.set(2, "Two");    cache.set(3, "Three");    cache.print();    System.out.println("----------------------");    // 尝试获取，提高1和3的使用率    cache.getValue(1);    cache.getValue(3);    cache.getValue(3);    // 容器已经满了，插入4的时候会覆盖最少使用的为2    cache.set(4, "Four");    cache.print();  }}