LeetCode 146 LRU Cache

class LRUCache {
    //创建一个私有的变量有序哈希map
    private LinkedHashMap<Integer,Integer> cache;
    static class LRUCacheImpl extends LinkedHashMap<Integer,Integer>{
        private int maxSize;
        public LRUCacheImpl(int capacity){
            //这里指定maxsize为true，类似于HashMap和concurrentHashMap，最后一个参数true说明可以指定该hashmap的大小
            super(capacity*2,0.75f,true);
            maxSize=capacity;
        }
        @Override
        protected boolean removeEldestEntry(Map.Entry<Integer,Integer> eldest){
            return size()>maxSize;
        }
    }
    public LRUCache(int capacity) {
        cache=new LRUCacheImpl(capacity);
    }
    
    public int get(int key) {
        return cache.getOrDefault(key,-1);
    }
    
    public void put(int key, int value) {
        cache.put(key,value);
    }
}