首先问一下程序的功能。
答：它需要一个密码
B：它为用户的每个密码字符创建一个arraylist。
C：它将创建的数组列表存储在Arraylist（ArrayList＆gt;）
中D：程序逐字逐句读入。加密字符（使用ADFGVX polybius方形密码）并将加密字符添加到arraylists。
如果密码是盖子，则第一个字符在列表1中，第二个字符在列表2中，第三个字符在列表3中，第四个字符再次列在列表1中。直到读完所有字符。
E：它按照第一个字符的字母顺序对列表进行排序。 所以密码[l，i，d]将排序为[d，i，l]
F：程序然后将字符解密回原始形式，将它们添加到打印到文件的数组列表中。
孔代码如下。我读入的文件大小为3,120KB，包含大约320万个字符。 在我的机器上，孔程序将在0.7秒内完成所有操作。
有没有办法让它跑得更快？ 我有一个想法是使用linkedhashmap存储arraylists而不是使用ArrayList＆gt;。
我从未使用过链接的hashmap，也不知道我将如何按字母顺序对列表进行排序。
任何可以帮助我加快计划的想法或建议都将不胜感激。 （我正在运行java 1.8）
package gmit;
import java.util.*;
import java.io.*;
import java.nio.charset.Charset;
public class project {
// Creating Hashmap
private static HashMap<String, String> stringmap = new HashMap<String, String>();
// Creating String Array lists
private static ArrayList<ArrayList<String>> mylist = new ArrayList<ArrayList<String>>();
private static ArrayList<String> lol = new ArrayList<String>();
// Declaring int variables
private static int encryptioncounter=0,decryptioncounter=0,lastindexcounter=0,mylistindexcounter=0;
// Declaring String variables
private static String password,value;
private static String result;
// ----------------------------------------------- Main start --------------------------------------------------------
public static void main(String[] args) throws IOException {
// Method to populate HashMap
putstuffinstrinmap();
System.out.println("Pleaseinput your passphrase");
// Gets user Input
Scanner in = new Scanner(System.in);
password = in.nextLine();
// Starts for loop
// Creates Array list in number of the amount of characters of the password
// Adds created arraylists to Arraylist<List> mylist.
for (int i = 0; i < password.length(); i++) {
List<String> firstCharandMore= new ArrayList<>();
char c = password.charAt(i);
firstCharandMore.add(String.valueOf(c));
mylist.add((ArrayList<String>) firstCharandMore);
}
//Starts Timer
long startTime = System.currentTimeMillis();
// Reads in File in UTF-8 format
// gets back a character
BufferedReader reader = new BufferedReader(
new InputStreamReader(
new FileInputStream("WarAndPeace-LeoTolstoy.txt"),
Charset.forName("UTF-8")));
int c;
while((c = reader.read()) != -1) {
char string = (char) c;
// Converts Character to upper case String
// Passes the string into encryption method
encrypt(Character.toString(string).toUpperCase());
// Adds one to counter
decryptioncounter++;
}
// Creates new Arraylist listToSort (Copy of mylist)
// Sorts Array lists in alphabetic order by first character from each list
List<List<String>> listToSort = new ArrayList<>(mylist);
listToSort.sort((l1, l2) -> l1.get(0).compareTo(l2.get(0)));
// Calls decryption method
decrypt();
writetofile();
// Ends Timer
long endTime = System.nanoTime();
long totalTime = endTime - startTime;
// Prints Time
double seconds = (double)totalTime / 1000000000.0;
System.out.println(seconds+" Total time");
}
// ------------------------------------ End Main -----------------------------------------
private static void writetofile() throws FileNotFoundException, UnsupportedEncodingException {
PrintWriter writer = new PrintWriter("finished.txt", "UTF-8");
StringBuilder builder = new StringBuilder();
for (String value : lol) {
builder.append(value);
}
String s = builder.toString();
//String s = lol.toString();
writer.println(s);
writer.close();
}
// -------------------------------- Encryption Start -------------------------------------
private static void encrypt(String string) {
// Gets
value= stringmap.get(string);
mylist.get(encryptioncounter).add(value);
// Adds one to counter
encryptioncounter++;
if(encryptioncounter>=password.length()){
encryptioncounter=0;
// Adds one to counter
lastindexcounter++;
}
}
// --------------------------------- Encryption End ---------------------------------------
// --------------------------------- Decryption Start -------------------------------------
private static void decrypt() {
int thiscounter=0;
while(decryptioncounter != thiscounter ){
for(int i=0;i <password.length() ;i++){
String ba = mylist.get(i).get(mylistindexcounter);
result= stringmap.get(ba);
lol.add(result);
thiscounter++;
if(mylistindexcounter >=lastindexcounter){
decryptioncounter =thiscounter;
}
}
mylistindexcounter++;
}
}
// ---------------------------------- Decryption End ---------------------------------------
// --------------------------------- Map population start ---------------------------------
public static void putstuffinstrinmap(){
stringmap.put("AA", "P");//AA - P
stringmap.put("AD", "H");//AD - H
stringmap.put("AF", "0");//
stringmap.put("AG", "Q");//
stringmap.put("AV", "G");//
stringmap.put("AX", "6");//
stringmap.put("DA", "4");//
stringmap.put("DD", "M");//
stringmap.put("DF", "E");//
stringmap.put("DG", "A");//
stringmap.put("DV", "1");//
stringmap.put("DX", "Y");//
stringmap.put("FA", "L");//
stringmap.put("FD", "2");//
stringmap.put("FF", "N");//
stringmap.put("FG", "O");//
stringmap.put("FV", "F");//
stringmap.put("FX", "D");//
stringmap.put("GA", "X");//
stringmap.put("GD", "K");//
stringmap.put("GF", "R");//
stringmap.put("GG", "3");//
stringmap.put("GV", "C");//
stringmap.put("GX", "V");//
stringmap.put("VA", "S");//
stringmap.put("VD", "5");//
stringmap.put("VF", "Z");//
stringmap.put("VG", "W");//
stringmap.put("VV", "7");//
stringmap.put("VX", "B");//
stringmap.put("XA", "J");//
stringmap.put("XD", "9");//
stringmap.put("XF", "U");//
stringmap.put("XG", "T");//
stringmap.put("XV", "I");//
stringmap.put("XX", "8");//
stringmap.put("P", "AA");//
stringmap.put("H", "AD");//
stringmap.put("0", "AF");//
stringmap.put("Q", "AG");//
stringmap.put("G", "AV");//
stringmap.put("6", "AX");//
stringmap.put("4", "DA");//
stringmap.put("M", "DD");//
stringmap.put("E", "DF");//
stringmap.put("A", "DG");//
stringmap.put("1", "DV");//
stringmap.put("Y", "DX");//
stringmap.put("L", "FA");//
stringmap.put("2", "FD");//
stringmap.put("N", "FF");//
stringmap.put("O", "FG");//
stringmap.put("F", "FV");//
stringmap.put("D", "FX");//
stringmap.put("X", "GA");//
stringmap.put("K", "GD");//
stringmap.put("R", "GF");//
stringmap.put("3", "GG");//
stringmap.put("C", "GV");//
stringmap.put("V", "GX");//
stringmap.put("S", "VA");//
stringmap.put("5", "VD");//
stringmap.put("Z", "VF");//
stringmap.put("W", "VG");//
stringmap.put("7", "VV");//
stringmap.put("B", "VX");//
stringmap.put("J", "XA");//
stringmap.put("9", "XD");//
stringmap.put("U", "XF");//
stringmap.put("T", "XG");//
stringmap.put("I", "XV");//
stringmap.put("8", "XX");//
stringmap.put("AH", ".");//
stringmap.put("DH", "!");//
stringmap.put("FH", "?");//
stringmap.put("GH", " ");//
stringmap.put("VH", "'");//
stringmap.put("XH", ",");//
stringmap.put(".", "AH");//
stringmap.put("!", "DH");//
stringmap.put("?", "FH");//
stringmap.put(" ", "GH");//
stringmap.put("'", "VH");//
stringmap.put(",", "XH");//
stringmap.put("AP", "]");//
stringmap.put("DP", "[");//
stringmap.put("FP", "~");//
stringmap.put("GP", "&");//
stringmap.put("VP", ":");//
stringmap.put("XP", ";");//
stringmap.put("AP", "-");//"
stringmap.put("DP", "");//
stringmap.put("FP", "*");//
stringmap.put("GP", "^");//
stringmap.put("VP", "\"");//
stringmap.put(null, " ");//
}
// --------------------------------- Map population End -----------------------------------
}
修改
根据Andy Turner的建议，我已将System.currentTimeMillis()更改为System.nanoTime();
所以时间测量已经改变了。 （上面的代码按此方式编辑）