LRU算法

import java.util.HashMap;
import java.util.LinkedList;

public class LRU {
    public static void main(String[] args) {
        LRU lru = new LRU();
        int[] item=new int[]{4,7,0,7,1,0,1,2,1,2,6};
        for (int i = 0; i < item.length; i++) {
            lru.push(item[i]);
        }
        lru.showList();
    }
    //容量
    private int N=5;

    //存放数组
    private LinkedList<Object> lists=new LinkedList<>();
    private HashMap<Object,Integer> hashMap=new HashMap<>();

    private boolean isFull(){
        return lists.size()>=N;
    }

    //返回插入位置索引
    public int push(Object obj){
        if(hashMap.containsKey(obj)){
            int index=hashMap.get(obj);//找到这个key的索引
            for(int i=index;i<lists.size()-1;i++){
                lists.set(i,lists.get(i+1));
                hashMap.put(lists.get(i),hashMap.get(lists.get(i))-1);
            }
            lists.set(lists.size()-1,obj);
            hashMap.put(obj,lists.size()-1);
        }
        else {
            if(!isFull()){
                hashMap.put(obj,lists.size());//放入索引，因为要在现在的list上追加，索引为lists.size()-1+1
                lists.add(obj);
            }
            else {
                Object first=lists.getFirst();
                hashMap.remove(first);
                lists.removeFirst();
                lists.add(obj);
                for (int i = 0; i < lists.size(); i++) {
                    hashMap.put(lists.get(i),i);
                }
            }
        }
        return hashMap.get(obj);
    }

    public void showList(){
        for (int i = 0; i < lists.size(); i++) {
            System.out.print(lists.get(i)+" ");
        }
    }
}