RLE v2

import java.io.InputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.nio.charset.Charset;

public class RLE{

    private static Byte[] stringToByteArray(String string) {
        byte[] bytes  = string.getBytes(Charset.forName("ASCII"));
        Byte[] result = new Byte[bytes.length];

        for(int i = 0; i < bytes.length; i++)
            result[i] = bytes[i];

        return result;
    }

    public static void main(String[] args){
        if(args.length == 0)
            throw new IllegalArgumentException("É necessário informar a string a ser comprimida.");

        Byte[] data = stringToByteArray(args[0]);

        System.out.println("Entrada......: " + Arrays.toString(data));
        data = compressRLE(data, 2);
        System.out.println("Comprimido...: " + Arrays.toString(data));
        System.out.println("Descomprimido: " + Arrays.toString(decompressRLE(data, 2)));
    }

    private static Byte[] compressRLE(Byte[] data, int n) {
        ArrayList<Byte> result = new ArrayList<Byte>();
        int count = 0;
        Byte last = 0;
        for(Byte b : data) {
            if(b != last || count == 0xFF + n) {
                writeRLE(last, count, n, result);
                last = b;
                count = 1;
            } else {
                count++;
            }
        }

        writeRLE(last, count, n, result);

        return result.toArray(new Byte[result.size()]);
    }

    private static Byte[] decompressRLE(Byte[] data, int n) {
        ArrayList<Byte> result = new ArrayList<Byte>();
        int count = 0;
        Byte last = 0;
        for(Byte b : data) {
            if(count == n) {
                count = b + n;
                for(int i = 0; i < count; i++)
                    result.add(last);
                count = 0;
            } else if (b != last) {
                for(int i = 0; i < count; i++)
                    result.add(last);
                last = b;
                count = 1;
            } else {
                count++;
            }
        }

        return result.toArray(new Byte[result.size()]);
    }

    private static void writeRLE(Byte b, int count, int n, ArrayList<Byte> result) {
        for(int i = 0; i < Math.min(count, n); i++)
            result.add(b);

        if(count >= n) {
            byte c = (byte)(count-n);
            result.add(c);
        }
    }
}