Cipher.java

import java.io.*;
import java.util.*;

public class Cipher {

    public static void main(String[] args) {
        Cipher c = new Cipher();
        System.out.println(c.encode("moopers!!! moop Moop moop DOOPA loop! azAZ`{} :)", 17));
        c.buildCorpusFreq("shakespeare.txt");
        System.out.println(Arrays.toString(c.getCF()));
    }

    private double[] CorpusFreqs;

    public Cipher() {
        CorpusFreqs = new double[26];
    }

    public double[] getCF() {
        return CorpusFreqs;
    }

    public String encode (String input, int shift) {
        shift = shift%26;
        input = input.toLowerCase();
        String output = "";
        for (int i=0;i<input.length();i++) {
            int asc = (int) input.charAt(i);
            if (96 < asc && 123 > asc) {
                asc+=shift;
                if (asc > 122)
                    asc = asc-26;
            }
            output+= (char)asc;
        }
        return output;
    }

    private void buildCorpusFreq(String filename) {
        int count = 0;
        int[] freqs = new int[26];
        try {
            Scanner sc = new Scanner (new File(filename));
            while (sc.hasNext()) {
                String s = sc.nextLine();
                for (int i=0;i<s.length();i++) {
                    char c = s.charAt(i);
                    c=Character.toLowerCase(c);
                    if ('a' <= c && c <= 'z') {
                        count+=1;
                        freqs[c-'a']+=1;
                    }
                }
            }
        }  catch (Exception e) {}
        for (int i=0;i<26;i++) {
            CorpusFreqs[i]=(freqs[i]*1.0/count);
        }
    }

    public Double vectDist (double[] a, double[] b,int length) {
	Double resulta = 0.0;
	
	for (int i=0;i<length;i++) {
	    resulta += (a[i]*a[i]);
	}
	
    }

    public String decipher(String filename) {
	double[] fileFreq = new double[26];
	 int count = 0;
        int[] freqs = new int[26];
        try {
            Scanner sc = new Scanner (new File(filename));
            while (sc.hasNext()) {
                String s = sc.nextLine();
                for (int i=0;i<s.length();i++) {
                    char c = s.charAt(i);
                    c=Character.toLowerCase(c);
                    if ('a' <= c && c <= 'z') {
                        count+=1;
                        freqs[c-'a']+=1;
                    }
                }
            }
        }  catch (Exception e) {}
        for (int i=0;i<26;i++) {
            fileFreq[i]=(freqs[i]*1.0/count);
        }
	return "moop";
    }
}