Nibble Encode via Shuffle

Building A Shuffle

import java.util.Arrays;
import static   BH.Bytes_Hex.*;

public class nibbleEncode {
    public static void main(String[] args) {
        new nibbleEncode();
    }
    public nibbleEncode(){
        // The string to encode.
        String letters = "Code it.";
        System.out.println("\n"+letters);
        byte[] theBytes = letters.getBytes();
        //As a Hex String
        String hexstring= ByteArray2HexString(theBytes);
        System.out.println("\n"+hexstring);
        //Get ready to apply the permutation.
        char[] theHexBytes=hexstring.toCharArray();
        System.out.println("\n"+Arrays.toString(theHexBytes));
        //Apply the permutation.
        int[] p=Shuffle();
        //int[] p={3,10,8,0,11,6,5,9,2,7,1,4,13,12,15,14};
        char[] Encoded=permute(theHexBytes,p);
        System.out.println("\nEncoded\n"+Arrays.toString(Encoded));
        String toSend=new String(Encoded);
        System.out.println("\nTo Send\n"+toSend);
        System.out.println("\nDecoded");
        char[] Decoded=permute(Encoded,p);
        String theResult=Arrays.toString(Decoded);
        System.out.println(theResult);
        byte[] DecodedBytes= HexArray2ByteArray(Decoded);
        System.out.println( ByteArray2String(DecodedBytes));
    }
    public char[] permute(char[] s, int[] p ){
        char[] encoded=new char[16];
        for (int i=0;i<16;i=i+1) {
            encoded[i]=s[p[i]];
        }
        return encoded;
    }
    public int[] Shuffle(){
        int N = 16;
        int r;
        int[][] a = new int[N][2];
        // insert integers 0..N-1
        for (int i = 0; i < N; i++) {
            a[i][0] = i;a[i][1]=0;
        }

        // shuffle
        for (int i = 0; i < N; i++) {
            if (a[i][1]==0) {
                a[i][1]=1;
                while (true) {
                    r = (int) (Math.random() * (N));
                    if (a[r][1]==0)break;
                }
                int swap = a[r][0];
                a[r][0] = a[i][0];
                a[r][1] =1;
                a[i][0] = swap;
            }
        }
        int [] p=new int[N];
        for (int i=0;i<16;i++)p[i]=a[i][0];
        return p;
    }
}