servidor que cambia un valor de un archivo de texto

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;
 
public class FileEditor{
   
public static void main(String[] args) throws IOException{
      File file = new File("file.txt");
      if(!file.exists()){
         file.createNewFile();
      }
      FileWriter writer = new FileWriter(file);
      Scanner reader = new Scanner(file);
 
      String line = "";
      int choice = 0;
     
      do{
         Scanner scan = new Scanner(System.in);
         System.out.println("1. add a line");
         System.out.println("2. Exit");
         choice = scan.nextInt();
         if(choice == 1){
            System.out.print("Enter: ");
            line = scan.nextLine();
            line = scan.nextLine();
            writer.write(line + "\n");
            writer.flush();
            System.out.println