本文实例为大家分享了java实现页面置换算法的具体代码,供大家参考,具体内容如下
原理就不说了,直接上代码
fifo
import java.util.arraylist; import java.util.list; import utils.listutils; /** * * * @author cnkeysky * */ public class fifo { public void run() { string[] inputstr = {"1", "2", "3", "4", "2", "1", "2", "3", "5", "2", "3", "7", "6"}; // 内存块 int memory = 3; list<string> list = new arraylist<>(); for(int i = 0; i < inputstr.length; i++){ if(i == 0){ list.add(inputstr[i]); system.out.println("第"+ i +"次访问:\t\t" + listutils.listtostring(list)); }else { if(listutils.find(list, inputstr[i])){ system.out.println("第" + i + "次" + "访问:\t\t" + listutils.listtostring(list)); }else{ if(list.size() < memory){ list.add(inputstr[i]); }else{ list.remove(0); list.add(inputstr[i]); } system.out.println("第" + i + "次" + "访问:\t\t" + listutils.listtostring(list)); } } } } }
lru
import utils.listutils; import java.util.arraylist; import java.util.list; /** * 最近最久未用置换算法 * @author cnkeysky * */ public class lru { public static void main(string[] args) { string[] inputstr = {"6", "7", "6", "5", "9", "6", "8", "9", "7", "6", "9", "6"}; // 内存块 int memory = 3; list<string> list = new arraylist<>(); for(int i = 0; i < inputstr.length; i++){ if(i == 0){ list.add(inputstr[i]); system.out.println("第"+ i +"次访问:\t\t" + listutils.listtostring(list)); }else { if(listutils.find(list, inputstr[i])){ // 存在字符串,则获取该下标 int index = listutils.findindex(list, inputstr[i]); // 下标不位于栈顶时,且list大小不为1时 if(!(list.get(list.size() - 1)).equals(inputstr[i]) && list.size() != 1) { string str = list.get(index); list.remove(index); list.add(str); } system.out.println("第" + i + "次" + "访问:\t\t" + listutils.listtostring(list)); }else{ if(list.size()>= memory) { list.remove(0); list.add(inputstr[i]); system.out.println("第" + i + "次" + "访问:\t\t" + listutils.listtostring(list)); }else { list.add(inputstr[i]); system.out.println("第" + i + "次" + "访问:\t\t" + listutils.listtostring(list)); } } } } } }
clock
import java.util.arraylist; import java.util.list; import utils.listutils; /** * * * @author cnkeysky * */ public class clock { public static void main(string[] args) { string[] inputstr = {"6", "7", "6", "5", "9", "6", "8", "9", "7", "6", "9", "6"}; list<string> list = new arraylist<>(); // 内存块 int memory = 3; // 缺页次数 int count = 0; string[] clock = new string[memory]; int indexnext = 0; int index = 0; // 初始化时钟 for(int i = 0; i < memory; i++) { clock[i] = "0"; } for(int i = 0; i < inputstr.length; i++) { int indexpre = 0; if (i == 0) { list.add(inputstr[i]); clock[indexnext] = "1"; indexnext++; system.out.println("第"+ i +"次访问:\t\t" + listutils.listtostring(list)); }else { if(listutils.find(list, inputstr[i])) { indexpre = listutils.findindex(list, inputstr[i]); if(clock[indexpre].equals("0")) { clock[indexpre] = "1"; } count++; system.out.println("第"+ i +"次访问:\t\t" + listutils.listtostring(list)); }else { if(list.size() < memory) { list.add(inputstr[i]); clock[indexnext] = "1"; indexnext++; system.out.println("第"+ i +"次访问:\t\t" + listutils.listtostring(list)); }else { index = listutils.findzero(indexnext, clock, memory); list.remove(index); list.add(index, inputstr[i]); clock[index] = "1"; indexnext = index + 1; system.out.println("第"+ i +"次访问:\t\t" + listutils.listtostring(list)); } } } if(indexnext > memory - 1) { indexnext = math.abs(memory - indexnext); } } system.out.println("缺页次数:" + (inputstr.length-count)); } }
工具类listutils
import java.util.list; public class listutils { public listutils() { } /** * 输出 * @param list 将list转为数组并输出, out: 2, 3, 4 * @return */ public static string listtostring(list list){ stringbuffer content = new stringbuffer(); for(int i = 0; i < list.size(); i++){ content.append(list.get(i)); if(i < list.size() - 1){ content.append(","); } } return content.tostring(); } /** * 在list中查找是否有str * @param list * @param str * @return */ public static boolean find(list<string> list, string str){ boolean flag = false; for(string lis : list){ if(lis.equals(str)){ flag = true; } } return flag; } /** * 在list中查找是否有string,如果有返回下标, 否则返回 -1 * @param list * @param str * @return */ public static int findindex(list<string> list, string str) { int index = 0; for(string lis : list) { if(lis.equals(str)) { return index; } index++; } return -1; } public static boolean clockjudge(string[] clock, int index) { if(clock[index].equals("0")) { return true; } return false; } /** * * @param index 下标 * @param clock 时钟 * @param range 当前使用内存块 * @return */ public static int findzero(int index, string[] clock, int range) { while(true) { if(clock[index].equals("0")) { break; }else { clock[index] = "0"; index++; if(index > range-1) { index = math.abs(range - index); } } } return index; } /** * 在数组中查找是否存在该字符串 * @param obj * @param str * @return */ public static boolean strjudge(object[] obj, string str) { boolean flag = false; if(obj == null) { return flag; } for(int i = 0; i < obj.length; i++) { if(str.equals(obj[i])) { flag = true; break; } } return flag; } /** * 获取二维数组中同一列的行的长度 * @param str 数据 * @param length 二维数组的列 * @param memory 内存块 * @return * */ public static int findnull(object[][] str, int length, int memory) { int index = 0; if(str == null) { return -1; } for(int i = 0; i < memory; i++) { if(str[i][length] != null) { index = i; } } return index; } }
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持移动技术网。
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