[JAVA] HEX from File

import java.io.FileInputStream;

import java.io.IOException;

import java.nio.file.Files;

import java.nio.file.Paths;

import org.apache.commons.codec.binary.Hex;

public class HexFileUtil {

    public static void main(String[] args) {

        String filePath = "path/to/your/file.txt";

        try {

            // Example 1: Read and convert hex string to byte array

            String hexString = Files.readString(Paths.get(filePath)).trim();

            byte[] byteArray = hexStringToByteArray(hexString);

            System.out.println("Byte array from hex string: " + java.util.Arrays.toString(byteArray));

            // Example 2: Read file as bytes and convert to hex string

            byte[] fileBytes = Files.readAllBytes(Paths.get(filePath));

            String hexStringFromFile = byteArrayToHexString(fileBytes);

            System.out.println("Hex string from file bytes: " + hexStringFromFile);

             // Example 3: Read file as bytes and convert to hex string using Apache Commons Codec

             byte[] fileBytes2 = Files.readAllBytes(Paths.get(filePath));

             String hexStringFromBytes = Hex.encodeHexString(fileBytes2);

             System.out.println("Hex string from file bytes using Apache Commons Codec: " + hexStringFromBytes);

            // Example 4: Read file and print it in hex representation using FileInputStream

            printHexStream(new FileInputStream(filePath), 16);

        } catch (IOException e) {

            System.err.println("Error reading file: " + e.getMessage());

        }

    }

    public static void printHexStream(final FileInputStream inputStream, final int numberOfColumns) throws IOException{

         long streamPtr=0;

         while (inputStream.available() > 0) {

             final long col = streamPtr++ % numberOfColumns;

             System.out.printf("%02x ",inputStream.read());

             if (col == (numberOfColumns-1)) {

                 System.out.printf("\n");

             }

         }

    }

    public static byte[] hexStringToByteArray(String hexString) {

        int len = hexString.length();

        byte[] data = new byte[len / 2];

        for (int i = 0; i < len; i += 2) {

            data[i / 2] = (byte) ((Character.digit(hexString.charAt(i), 16) << 4)

                                 + Character.digit(hexString.charAt(i + 1), 16));

        }

        return data;

    }

    public static String byteArrayToHexString(byte[] bytes) {

        StringBuilder sb = new StringBuilder();

        for (byte b : bytes) {

            sb.append(String.format("%02x", b));

        }

        return sb.toString();

    }

}