import java.util.ArrayList;

 public class LRUCache {

     private int cacheMaxSize = 0;

     private ArrayList<Integer> pages = null; // Interger means page id

     public LRUCache(int cacheMaxSize) {

         this.cacheMaxSize = cacheMaxSize;

         pages = new ArrayList<Integer>();

     }

     public void add(Integer p) {

         if (pages.contains(p)) {

             pages.remove(p);

             pages.add(p);

         } else if (pages.size() == cacheMaxSize) {

             pages.remove(0);

             pages.add(p);

         } else {

             pages.add(p);

         }     }

 }

import java.util.ArrayList;

import java.util.Scanner;

import xqy.been.LRUCache;

public class LRU {

    private Scanner sc;

    private LRUCache lc = null;

    private ArrayList<Integer> pages = null;

    public LRU() {

        sc = new Scanner(System.in);

        pages = new ArrayList<Integer>();

        init();

        op();

    }

    private void init() {

        int key = -2;

        System.out.print("<LRU> 请输入物理块个数：");

        lc = new LRUCache(sc.nextInt());

        System.out.println("<LRU> 请按顺序输入页号(exit: -1): ");

        while (key != -1) {

            key = sc.nextInt();

            if (key > 0) {

                pages.add(key);

            }

        }

    }

    private void op() {

        for (int i = 0; i < pages.size(); i++) {

            lc.add(pages.get(i));

        }

    }

    public static void main(String[] args) {

        new LRU();

    }

}