File Reader in Java

Question

In java: I am reading a file named fn. It is a text file, and the first number gives the number of lines and characters:

Example:

4
AFBA\n 
BBBB\n 
EFHE\n 
EFJH\n

Theres a new line after each 4 characters. This goes for 4 rows.

What I have so far is:

File fp = new File(fn);
FileReader fr = new FileReader(fp);
BufferedReader bfr = new BufferedReader(fr);

How do I create a java algorithm to store this data in a data structure, such as an array list, array, stack, etc.

Thanks so much. I'm just getting started programming so sorry if this question doesn't match the Stack overflow rhetoric.

1) how do i store the first line in a different int, 2) what data strucutre would be best to store this in? — snowbarr, Jul 28 '20 at 06:36

Ayush28 · Answer 1 · 2020-07-28T06:29:46.387

2

You can use Java 8 Stream API and nio library to store each line as an object in a collection. For example:

import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.stream.Stream;
import java.util.*;

public class streamFileRead {

    public static void main(String args[]) {

        String fileName = "drive://location//fn.txt";
        List<String> list = new ArrayList<String>();
        
        try (Stream<String> stream = Files.lines(Paths.get(fileName))) {

            list = stream.collect(Collectors.toList());

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}

I guarantee this is way more fast and foolproof than reading each line using a loop and identifying line breaks using \n.

edited Jul 28 '20 at 06:29

answered Jul 28 '20 at 06:14

Ayush28

359
3
18

If you use nio, you could also use https://docs.oracle.com/javase/7/docs/api/java/nio/file/Files.html#readAllLines(java.nio.file.Path,%20java.nio.charset.Charset). – dan1st Jul 28 '20 at 06:19
1

There is `BufferedReader#lines`, too. And what apache library do you mean? – dan1st Jul 28 '20 at 06:21
@dan1st the library is `java.nio`. – Ayush28 Jul 28 '20 at 06:27
1

And since when is that an apache library and not default java? – dan1st Jul 28 '20 at 06:29
And where exactly is `Files.lines`, then? Do you mean the method in `BufferedReader`? – dan1st Jul 28 '20 at 06:38

score 0 · Answer 2 · answered Jul 28 '20 at 06:23

You can try this :

class ReadFile{
    public static void main(String[] args) throws IOException {
        File fp = new File(fn);
        FileReader fr = new FileReader(fp);
        BufferedReader bfr = new BufferedReader(fr);
        List<String> list= new ArrayList<>();
        String s="";
        while( (s=(bfr.readLine()))!=null){
            list.add(s);
        }
        System.out.print(list);
    }
}

File Reader in Java

2 Answers2