Vignere Cipher

Vignere.java

import java.util.Scanner;

/*
 * IsonProjects
 */

public class Vignere {
	private final String alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    
	private char matrix[][];
	
	public Vignere(){
		matrix = new char[26][26];
		
		int pos = 0;
		for (int i = 0; i<alphabet.length(); i++){
			for (int j = 0; j < alphabet.length(); j++){
				int mov = (pos + j) % alphabet.length();
				matrix[i][j] = alphabet.charAt(mov);
			}
			pos++;
		}
	}
	
	public Vignere(String alphabet){
		matrix = new char[alphabet.length()][alphabet.length()];
		
		int pos = 0;
		for (int i = 0; i<alphabet.length(); i++){
			for (int j = 0; j < alphabet.length(); j++){
				int mov = (pos + j) % alphabet.length();
				matrix[i][j] = alphabet.charAt(mov);
			}
			pos++;
		}
	}
	
	public String encode(String key, String input){
		String out = "";
		String strippedInput = input.replace(" ", "");	// remove spaces
		
		key = key.toUpperCase();
		strippedInput = strippedInput.toUpperCase();
		
		int repeat = strippedInput.length() / key.length();
		String keyStr = "";
		
		for (int i = 0; i < repeat; i++){
			keyStr += key;
		}
		
		int surplass = strippedInput.length() % key.length();
		keyStr += key.substring(0, surplass);
		
		
		int k = 0;
		for (int i=0; i<input.length(); i++){
			if(input.charAt(i) == ' '){
				out += ' ';
			}
			else{
				int row = keyStr.charAt(k) - 'A';
				int col = strippedInput.charAt(k) - 'A';
				
				out += matrix[row][col];
				k++;
			}
		}
				
		return out;
	}
	
	public String decode(String key, String input){
		String out = "";
		String strippedInput = input.replace(" ", "");	// remove spaces
		
		key = key.toUpperCase();
		strippedInput = strippedInput.toUpperCase();
		
		int repeat = strippedInput.length() / key.length();
		String keyStr = "";
		
		for (int i = 0; i < repeat; i++){
			keyStr += key;
		}
		
		int surplass = strippedInput.length() % key.length();
		keyStr += key.substring(0, surplass);
		
		int k = 0;
		for (int i=0; i<input.length(); i++){
			if (input.charAt(i) == ' '){
				out += ' ';
			}
			else{
				int row = keyStr.charAt(k) - 'A';
				int col = 0;
				
				for (int j=0; j<matrix[i].length; j++){
					if (matrix[row][j] == strippedInput.charAt(k)){
						col = j;
						k++;
						break;
					}
				}
				
				out += (char)('A' + col);
			}
		}
				
		return out;
	}
	
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		
		Vignere vignere = new Vignere("ABCDEFGHIJKLMNOPQRSTUVWXYZ");
		
		System.out.print("Enter key(without space): ");
		String key = scanner.nextLine();
		while(true){
			System.out.print("Enter choice (0. Exit 1. Encode 2. Decode): ");
			int choice = Integer.parseInt(scanner.nextLine());
			
			if (choice == 0){
				break;
			}else{
				if (choice == 1){
					System.out.print("Enter string to encode: ");
					String input = scanner.nextLine();
					System.out.println("Encoded output: " + vignere.encode(key, input));
				}
				else{
					System.out.print("Enter string to encode: ");
					String input = scanner.nextLine();
					System.out.println("Decoded output: " + vignere.decode(key, input));
				}
			}
		}
		
		System.out.println("-----EXIT-----");
	}
}