Cipher.java

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

public class Cipher {
    private double[] CorpusFreqs;
    
    public Cipher() {
        CorpusFreqs = new double[26];
    }
    
    public void buildCorpusFreq(String filename) {
        try {
	    Scanner sc = new Scanner (new File(filename));
         while (sc.hasNext()) {
	     String s = sc.nextLine();
	     s = s.toLowerCase();
	     for (int i=0;i<s.length();i++) {
                 char c = s.charAt(i);
                 if (c >= 'a' && c <= 'z')
		     CorpusFreqs[c-'a']++;
	     }
         }
        } 
	catch (Exception e) {}
    }
    
    
    public double[] getCorpusFreq() {
        return CorpusFreqs;
    }
    
    public String encode(String s, int diff) {
        char c;
        String result = "";
        s = s.toLowerCase();
        for (int i=0; i<s.length(); i++) {
	    c = s.charAt(i);
	    if (c >= 'a' && c <= 'z') {
                if (c+diff > 'z') {
		    c = (char) (c + diff - 26);
                } else
                 c = (char) (c + diff);
	    }
	    result = result + Character.toString(c);
        }
        return result;
    }   
}