Question

Java Code Question:
The program is supposed to read a file and then do a little formatting and produce a new txt file. I have that functionality down.

My problem is that I also need to get my program to correctly identify if a file is empty, but so far I've been unable to. Here is my program in full:

import java.io.*;

import java.util.Scanner;

public class H1_43 {

public static void main(String[] args) {

Scanner scanner = new Scanner(System.in);

System.out.print("Enter java file: ");

String fileName = scanner.nextLine();

if (fileName.isEmpty()) {

System.out.println("This is an empty file");

} else {

try {

Scanner fileReader = new Scanner(new File(fileName));

PrintWriter printWriter = new PrintWriter(new FileWriter(fileName + ".txt"));

int lineNumber = 1;

while (fileReader.hasNextLine()) {

String line = fileReader.nextLine();

printWriter.printf("[%03d]", lineNumber++);

printWriter.println(line);

printWriter.flush();

}

fileReader.close();

printWriter.close();

} catch (FileNotFoundException e) {

System.out.println("Error: Unable to open/read data from file: " + fileName);

System.exit(0);

} catch (IOException e) {

System.out.println("Error: Unable to open/write data to file: " + fileName);

System.exit(0);

}

System.out.println("File generated successfully.");

}

}

}

Answer 1

Answer:

Edited code is as below: You were checking the length of the string (file name) that is entered by the user empty or not, while you have to first read the file then empty test.

I have edited the code at two place only. Please check commented line.

import java.io.*;
import java.util.Scanner;
class Main
{
  public static void main(String[] args) 
  {
    Scanner scanner = new Scanner(System.in);
    System.out.print("Enter java file: ");
    String file = scanner.nextLine();
    //To read a file
    File fileName = new File(file);
      try 
      {
        Scanner fileReader = new Scanner(new File(file));
        if (!fileReader.hasNextLine())
        {
          System.out.println("This is an empty file");
        } 
        else 
        {
          PrintWriter printWriter = new PrintWriter(new FileWriter(fileName + ".txt"));
          int lineNumber = 1;
          while (fileReader.hasNextLine()) 
          {
            String line = fileReader.nextLine();
            printWriter.printf("[%03d]", lineNumber++);
            printWriter.println(line);
            printWriter.flush();
          }
          fileReader.close();
          printWriter.close();
          System.out.println("File generated successfully.");
        }
        
      } 
      catch (FileNotFoundException e) 
      {
        System.out.println("Error: Unable to open/read data from file: " + fileName);
        System.exit(0);
      } 
      catch (IOException e) 
      {
        System.out.println("Error: Unable to open/write data to file: " + fileName);
        System.exit(0);
      }
    }
}

Please give thumbsup, or do comment in case of any query. Thanks.