2D Arrays in Java Program

Question

My program is supposed to gets a phrase from the user then returns to the user an encrypted code of their choice (either ROT13 or ATBASH) of the phrase they entered. My code compiles and everything and lets the user input the required stuff but when they enter the phrase to be encrypted, nothing happens.. like the new encrypted code doesnt show up, and i dont know what wrong with it! Please help! Thank you!

   import java.io.*;

public class J4_1_EncryptionVer4
{
  public static void main (String [] args) throws IOException
  {
    BufferedReader myInput = new BufferedReader (new InputStreamReader (System.in));//BufferedReader reads user input

    //String array letterA[] is initialized
    String [][] letterA = new String [][]{
    {"A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"},
    {"N","O","P","Q","R","S","T","U","V","W","X","Y","Z","A","B","C","D","E","F","G","H","I","J","K","L","M"},
    {"Z","Y","X","W","V","U","T","S","R","Q","P","O","N","M","L","K","J","I","H","G","F","E","D","C","B","A"},
    };

    System.out.println ("Enter '1' for ROT13 or '2' for ATBASH");//asks user to choose method
    String numA = myInput.readLine();//reads user input and assigns it to string
    int num = Integer.parseInt (numA);//converts string to integer
    int a = 0;//int a is declared

    if (num == 1){//if user enters 1
          a = 1;//set a to 1
    }
    if (num == 2) {//end if//if user enters 2
          a = 2;//set a to 2
        }//end if
    System.out.println ( a);
    System.out.println(num);

    System.out.println ("Please enter a phrase: ");//asks user to enter phrase
    String message = myInput.readLine();//reads user input and assigns it to string

    int x = 0; //declares int var x

    System.out.println ("Your Encrypted code is: ");//prints out scentence


    while (x < message.length())//while loop will run while x is less that the phrase length          
    {
      String text = message.toUpperCase();//converts user input to upper case
      String letter = Character.toString(text.charAt(x));//extracts character from string and assigns it to another string letter

      x++;//increments x by 1 each time

      for(int i=0; i<letterA.length; i++)//for loop declares int i = 0, will run while i is less than the the length of the array letterA, and i will increment by 1 each time
      {
        if(letter.equals(letterA[a][i]))//if the letter is equal to letterA[i]
        {
          System.out.print (letterA[a][i]);//print out the corresponding letter

          break;//breaks from loop

        }//end if

        else if (letter.equals(" "))//else id the letter is equal to a space
        {
          System.out.print(" ");//prints out space
          break;//breaks from loop
        }//end else if        
      }//end for loop
    }//end while loop
  }//end main
}//end class

Answer 1

I think you should change your for loop to

    for (int i= 0; i < letterA[0].length ; i++ ) {
           if (letter.equals(letterA[0][i]) {
               System.out.print(letterA[a][i]);
               break;              
           }
           else {
                // .........,.......
           }
    }

First use the first array as basis. Compare the letters then if they are equal then get the index of that letter to be used in encrypting

I'm using a bloody phone ryt now so I didn't really compile your code

Answer 2

This doesn't work because letterA.length is 3, so your for loop only runs through 3 iterations, instead of 26.