Cfrgtkky

I have to make a program that reads input from a file, encodes it with random characters and integers into a random file and then decode the randomfile to print the original data from the input file in the console.

I did this for the encoding part:

public class Encoder implements IEncoder {



    public void encode(String inputFileName, String outputFilePath) throws IOException{

        File file = new File(inputFileName);



        //load characters into the character array 

        char chars = {'a', 'b', 'c', 'd','e', 'f', 'g', 'h', 'i', 'j', 'k', 'l'};



        RandomAccessFile randFile = new RandomAccessFile(outputFilePath, "rw");



        ArrayList<Character> list = new ArrayList<Character>();



        String k = "";



        //scan  input file, save into string 



        try {

            Scanner scan = new Scanner(file);

            while(scan.hasNextLine()) {

                k=k+scan.nextLine();

            }



        scan.close();

        } catch (FileNotFoundException e) {

            System.out.println("There was an issue with the file...");

        }



        //save data from the input file into the ArrayList 



        for(int i = 0; i < k.length(); i++) {

            list.add(k.charAt(i));

        }



        //write each character into a binary file, along with a random integer n, followed by n random characters



        for(int j = 0; j< list.size()-1; j++) {

            int n = ThreadLocalRandom.current().nextInt(1, 20 + 1);

            randFile.writeChar(list.get(j));

            randFile.writeInt(n);



            for (int m = 0; m < n; m++) {

                int z = ThreadLocalRandom.current().nextInt(1, 11 + 1);

                randFile.writeChar(chars[z]);

            }

        }



        randFile.writeChar(list.get(list.size() - 1));

        randFile.writeInt(-1);

        randFile.close();

    }

}

This is for the decoder.

public class Decoder implements IDecoder {



    @Override

    public void decode(String filePath) throws IOException {



        //read the random access file 

        RandomAccessFile randFile = new RandomAccessFile(filePath, "r");



        //create a string to print the output to console

        String k ="";



        //initialize the array list 

        ArrayList<Character> list = new ArrayList<Character>();







        for(int i = list.size()-1 ; i> 0 ; i--) {

            char c = randFile.readChar();

            int n = randFile.readInt();

            // int z = ThreadLocalRandom.current().nextInt(1, 20 + 1);



            for(int m = 0; m < n; m++) {

                // int x = ThreadLocalRandom.current().nextInt(1, 11 + 1);

                k = k + c;

            }

        }



        //print the output and close the random access file 

        System.out.println("The data is" + k);

        randFile.close();

    }



}

My main issue is that I can't figure out a way to store the characters from the randomfile skipping all those random stuff.

this is the question:

You are to write a Java program to encode and decode a text file. The encoder reads a message stored in a plain text file, encodes it, and stores it in a binary file. The decoder reads the binary file, decodes the message and prints it to the console.

The encoding algorithm works as follows:

• Each character c in the message is followed by a randomly-generated number n ranging from 1 to 20. n is the number of bytes of random data between c and the next character in the message. So, after writing c followed by n to the file, there should be n byte locations (with random data) before the next character c is written.

• The last character is followed by the number -1 which indicates the end of the message.

• Each character stored in the binary file occupies 2 bytes while each integer occupies 4 bytes. Random data is stored between the integer following each character and the next character.

My main issue is that I can't figure out a way to store the characters from the randomfile skipping all those random stuff.

The builder you are looking for is a StringBUilder.

Additionally you should look at the skipBytes method of your reader.

Putting those together, your decoder would look something like this (not accounting for edge cases):

   public class Decoder implements IDecoder {



    @Override

    public void decode(String filePath) throws IOException {



        //read the random access file 

        RandomAccessFile randFile = new RandomAccessFile(filePath, "r");



        //create a string to print the output to console

        StringBuilder builder = new StringBuilder();



        while(true) {

            char c = randFile.readChar();

            builder.append(c);

            int n = randFile.readInt();

            if(n == -1) break;

            randFile.skipBytes(n);



        }



        //print the output and close the random access file 

        System.out.println("The data is" + builder.toString());

        randFile.close();

    }



}