Why close the BufferedReader if I'm not using it?

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I wrote this code without using the BufferedReader (as I actually wasn't told to do so). But, according to the validator, I still have to close it.... So, should I use it instead of the Scanner or the InputStream? I'm slightly puzzled;)

package com.codegym.task.task13.task1318; import java.io.BufferedReader; import java.io.InputStreamReader; import java.util.Scanner; import java.io.FileInputStream; import java.io.InputStream; import java.io.IOException; /* Reading a file */ public class Solution { public static void main(String[] args) throws IOException { Scanner console = new Scanner(System.in); String fileName = console.nextLine(); //InputStream inStream = new FileInputStream("c:/source.txt"); InputStream in = new FileInputStream(fileName); /* while (inStream.available() > 0) { int data = inStream.read(); //read one byte from the input stream outStream.write(data); //write that byte to the other stream. } */ while (in.available() > 0) { int data = in.read(); System.out.print((char) data); } in.close(); console.close(); } }

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Evgeniia Shabaeva

Level 27 , Budapest, Hungary

5 July, 11:30

Thank you, everybody! I tried deleting the import of java.io.BufferedReader, but it didn't help:). So I understood I had to use this BufferedReader anyway, even though I'm kinda struggling with it. I tried to use it instead of the Scanner, as we'd been taught previously, but that didn't work. I also tried using it to read the data from the file, whose address I'd read with the help of the Scanner, but that didn't work either. So, finally, I used the BufferedReader at the beginning of the code to get the address of the source file (BufferedReader buffer = new BufferedReader(new InputStreamReader(System.in)); String src = buffer.readLine();), then opened a stream of data from that file (FileInputStream fileInStream = new FileInputStream(src);) and read the lines from it with the help of the Scanner. Than I just printed the data using a while-loop (while(scanner.hasNextLine()) { System.out.println(scanner.nextLine());}). And closed the scanner and the sweet BufferedReader:). This solution is better than my original one also because it lets the program read string lines from the file, not just int values. However, the task does not specify what type of data we need to read, so this advantage is not obvious.

Thomas

Level 41 , Bayreuth, Germany

5 July, 11:49

There are probably uncountable approaches and, as you mentioned, if the requirements aren't totally clear then even some approaches more. Nowadays you usually do not use a plain InputStream (byte) or Reader (text) class anymore but some methods from the Files class (but that probably won't validate). Because you are supposed to print the result on the console I assume CG is looking for a text and not the 'byte' output. So here some ideas: That here should validate

try (BufferedReader console = new BufferedReader(new InputStreamReader(System.in));
     InputStream in = new FileInputStream(console.readLine())) {
    // that's not really understandable and maintainable coding and I would not do that in a team
    for (int c; (c = in.read()) != -1; System.out.print((char) c)) ;
}

Or nio, the Files class I mentioned above and you usually use now - if you want to read the file as bytes (won't validate as it uses newer (> Java 8) functionality)

try (BufferedReader console = new BufferedReader(new InputStreamReader(System.in))) {
    byte[] content = Files.readAllBytes(Path.of(console.readLine()));
    System.out.println(new String(content));
    // or stream it
    new String(content).lines().forEach(System.out::println);
}

If you want to read text lines (alternative: readAllLines(Path path) -> returns a List<String> and not a Stream<String>) To make this validate one could use BufferedReader instead of Files. The first also has a lines method.

try (BufferedReader console = new BufferedReader(new InputStreamReader(System.in));
     Stream<String> in = Files.lines(Path.of(console.readLine()));) {
    in.forEach(System.out::println);
}

Thomas

Level 41 , Bayreuth, Germany

5 July, 12:02

Approach with the BufferdReaders lines() method (probably may validate)

try (BufferedReader console = new BufferedReader(new InputStreamReader(System.in));
     BufferedReader in = new BufferedReader(new FileReader(console.readLine()))) {
    in.lines().forEach(System.out::println);
}

For InputStream and Writer classes there are just a few things to remember InputStream: - for reading bytes - reads single bytes from the file (but returns them as int). You can convert each byte to a char Reader: - for reading text files BufferedReader: - a useful implementation of Reader with some additional functionality. Eg. it is able to read entire lines. Here you need to remember that it strips off the linebreak. So If you need that (like when wanting to print the content), then you need to readd it (eg. using System.out.println() over print()) InputStreamReader: - a bridge between InputStream and Reader classes That's why you can use System.in (InputStream) in a Reader (BufferedReader) object

Nicolae Norocel

Level 26 , Milan, Italy

Expert

4 July, 13:33

Although you cannot see it directly in your code, I think the FileInputStream that reads the fileName uses the BufferedReader behind the curtains so you must close it as well. However, I am not sure.

Anonymous #11492773

Level 31 , Germany, Germany

4 July, 12:10

I think in this task you are expected to use a buffered reader although scanner should be working fine.

MoJo

Level 22 , Cairns, Australia

Expert

2 July, 22:23

Maybe since you imported the package, it's expecting a BufferedReader to be closed. Dunno...

Thomas

Level 41 , Bayreuth, Germany

2 July, 16:10

No clue how the validator is testing this but it might be related to imports. If that's the case then removing unused imports may help... or it really expects you to use a BufferedReader?