LinkedHashMap实现LRU缓存机制

public class LRUCache extends LinkedHashMap <Integer,Integer>{
    private int capacity;
    public LRUCache(int capacity){
        super(capacity,0.75f,true);
        this.capacity=capacity;
    }

    public int get(int key){
        return super.getOrDefault(key,-1);
    }
    public void put(int key,int value){
        super.put(key,value);
    }

    @Override
    protected boolean removeEldestEntry(Map.Entry<Integer, Integer> eldest) {
        return size()>capacity;
    }
}
/**
 * LRUCache 对象会以如下语句构造和调用:
 * LRUCache obj=new LRUCache(capacity)
 * int param_1=obj.get(key)
 * obj.put(key,value)
 *
 * 时间复杂度：O(1),因为是有序字典
 * 空间复杂度：O(capacity)
 */