Read and Write to the same text file

Question

I have written this code to read from the file first after hashing the content from the file. It will write the original content plus hash values. But when I try to run the program the program will keep on writing and won't stop. what is the problem with my code?

package Encrypt;

import java.io.*; 
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.Scanner;

public class Test {

public static void main(String[] args) throws Exception {  
    File file = new File("C:\\Users\\Tan\\Desktop\\Test.txt");
    Scanner scan = new Scanner(file);
    FileWriter writer = new FileWriter("C:\\Users\\Tan\\Desktop\\Test.txt", true);
            
        while(scan.hasNextLine()) {
            String password = scan.nextLine();
            MessageDigest md;
            try {
                // Select the message digest for the hash computation -> SHA-256
                md = MessageDigest.getInstance("SHA-256");

                // Generate the random salt
                SecureRandom random = new SecureRandom();
                byte[] salt = new byte[16];
                random.nextBytes(salt);

                // Passing the salt to the digest for the computation
                //md.update(salt);

                // Generate the salted hash
                byte[] hashedPassword = md.digest(password.getBytes(StandardCharsets.UTF_8));
                
                StringBuilder sb = new StringBuilder();
                for (byte b : hashedPassword)
                    sb.append(String.format("%02x", b));
                //Print output
                System.out.println(password + " "  + sb.toString());
                //write output to text file
                writer.write(password + " "  + sb + System.getProperty("line.separator"));
                writer.flush();
            }
            catch (NoSuchAlgorithmException e)
            {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        scan.close();
        writer.close();
    } 
}

Answer 1

You specified true as the append argument of FileWriters constructor. So you are probalby reading what you previously written into the file.