Hello first of all what the program does.
A: It takes in a password
B: It creates an arraylist for each character of the password from the user.
C: It stores the created array lists in a Arraylist (ArrayList>)
D: Program reads in a book Character by character. Encrypts the character (using the ADFGVX polybius square cipher) and adds the encrypted characters to the arraylists.
If the password is lid the First character goes in list one, 2nd character into list 2, 3rd into list 3 and 4th into list 1 again. Till all characters are read in.
E: It sorts the lists in alphabetical order of the first character. So The password [l,i,d] would be sorted to [d,i,l]
F: The program then decrypts the characters back into its original form adds them into an array list what is printed to a file.
The hole code is below. The file i read in is 3,120KB in size and it contains about 3.2 million characters. On my machine the hole program will do everything in 0.7 seconds.
Is there a way I can get it to run faster? One Idea I had was using a linkedhashmap to store the arraylists instead of using ArrayList>.
I have never used a linked hashmap and don't know how i would sort the lists then in alphabetical order.
Any ideas or suggestions that could help me speed up the program would be greatly appreciated. (I am running 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 -----------------------------------
}
EDIT:
On advice of Andy Turner I have changed System.currentTimeMillis() to System.nanoTime();
So the time measuring has changed. (Code above is edited to that way)
