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
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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
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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
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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
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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服务器之家。
原文链接：https://blog.csdn.net/cnkeysky/article/details/80639376
