用JAVA实现FIFO算法和LUR算法

FIFO算法和LUR算法都是常见的缓存置换算法，下面分别给出JAVA实现。

FIFO算法实现：

import java.util.*;

public class FIFO {
    private Queue<Integer> cache;
    private int capacity;

    public FIFO(int capacity) {
        this.capacity = capacity;
        cache = new LinkedList<>();
    }

    public void refer(int page) {
        if (!cache.contains(page)) {
            if (cache.size() == capacity) {
                cache.remove();
            }
            cache.add(page);
        }
    }

    public void display() {
        System.out.println(cache);
    }

    public static void main(String[] args) {
        FIFO cache = new FIFO(3);
        cache.refer(1);
        cache.refer(2);
        cache.refer(3);
        cache.refer(4);
        cache.refer(1);
        cache.refer(2);
        cache.display();
    }
}

LUR算法实现：

import java.util.*;

public class LRU {
    private LinkedHashMap<Integer, Integer> cache;
    private int capacity;

    public LRU(int capacity) {
        this.capacity = capacity;
        cache = new LinkedHashMap<>();
    }

    public void refer(int page) {
        if (cache.containsKey(page)) {
            cache.remove(page);
        } else if (cache.size() == capacity) {
            Iterator<Map.Entry<Integer, Integer>> iterator = cache.entrySet().iterator();
            iterator.next();
            iterator.remove();
        }
        cache.put(page, page);
    }

    public void display() {
        System.out.println(cache.keySet());
    }

    public static void main(String[] args) {
        LRU cache = new LRU(3);
        cache.refer(1);
        cache.refer(2);
        cache.refer(3);
        cache.refer(4);
        cache.refer(1);
        cache.refer(2);
        cache.display();
    }
}