MyFileWriter.java

import java.io.*;
import java.nio.file.*;
import java.nio.charset.StandardCharsets;
// for sha-356
import java.math.BigInteger;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MyFileWriter {
    public static void main(String[] args) throws IOException {
    String fileName = "example.txt";
    String data = "Talia!"; 

    try (FileWriter writer = new FileWriter(fileName, false)) {
        writer.write(data); 
    } catch (IOException e) {
        e.printStackTrace();
    }

    String hash = hashFile(fileName);
    System.out.println("SHA-256 of " + fileName + ": " + hash);
}


    public static void generateHiddenFile(String password, String fileName) {
        try {
            Files.write(Paths.get(fileName), password.getBytes(StandardCharsets.UTF_8));
        } catch (IOException e) {
            e.printStackTrace();
        }
        //hi!
    }

    // Calculate and print the file size using the File class
    private static void printFileSize(String... fileNames) {
        long totalSize = 0;
        for (String fileName : fileNames) {
            File file = new File(fileName);
            if (file.exists()) {
                totalSize += file.length();
            }
        }
        System.out.println("Total size of all files: " + totalSize + " bytes");
    }

    /**
    * Reads a text file and returns its contents as a string.
    * 
    * @param filePath the path to the file
    * @return the contents of the file as a string
    * @throws IOException if an I/O error occurs
    */
    public static String stringify(String filePath) throws IOException {
        // TODO: Implement this method
        // Read the file at filePath and return its contents as a String
        Path fileP = Paths.get(filePath);
        return Files.readString(fileP);
    }

    public static String hashFile(String filePath){
        try {
            MessageDigest sha256 = MessageDigest.getInstance("SHA-256");
            // reading the file in chunks of 1024 bytes at a time
            try (InputStream fileInputS = new FileInputStream(filePath)) {

            byte[] temporary = new byte[1024];
            int numberBytes = fileInputS.read(temporary);
            while (numberBytes != -1) {
                sha256.update(temporary, 0, numberBytes);
                numberBytes = fileInputS.read(temporary);
            }
            byte[] hashBytes = sha256.digest();
            StringBuilder str = new StringBuilder();
            // Converts the resulting hash to a hexadecimal string format
            for (byte b : hashBytes) {
                String hex = String.format("%02x", b);
                str.append(hex);
            }
            return str.toString();
        }

        } catch (FileNotFoundException e) {
            System.err.println("Error: File not found -> " + filePath);
        } catch (IOException e) {
            System.err.println("Error reading file: " + e.getMessage());
        } catch (NoSuchAlgorithmException e) {
            System.err.println("Error: SHA-256 algorithm not available.");
        }
        return null;
    }

}