Question

From aperformance optimization point of view: Reading a file in Java – is a buffered reader or scanner better?

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.logging.Level;
import java.util.logging.Logger;


public class BufferedReaderExample {   

    public static void main(String args[]) {

        //reading file line by line in Java using BufferedReader       
        FileInputStream fis = null;
        BufferedReader reader = null;

        try {
            fis = new FileInputStream("C:/sample.txt");
            reader = new BufferedReader(new InputStreamReader(fis));

            System.out.println("Reading File line by line using BufferedReader");

            String line = reader.readLine();
            while(line != null){
                System.out.println(line);
                line = reader.readLine();
            }           

        } catch (FileNotFoundException ex) {
            Logger.getLogger(BufferedReaderExample.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IOException ex) {
            Logger.getLogger(BufferedReaderExample.class.getName()).log(Level.SEVERE, null, ex);

        } finally {
            try {
                reader.close();
                fis.close();
            } catch (IOException ex) {
                Logger.getLogger(BufferedReaderExample.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
  } 

Output:
Reading File line by line using BufferedReader
first line in file
second line
third line
fourth line
fifth line
last line in file

and the other approach of scanner is..

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.Scanner;

/**
 * @author Javin Paul
 * Java program to read file line by line using Scanner. Scanner is a rather new
 * utility class in Java and introduced in JDK 1.5 and preferred way to read input
 * from console.
 */
public class ScannerExample {


    public static void main(String args[]) throws FileNotFoundException  {

       //Scanner Example - read file line by line in Java using Scanner
        FileInputStream fis = new FileInputStream("C:/sample.txt");
        Scanner scanner = new Scanner(fis);

        //reading file line by line using Scanner in Java
        System.out.println("Reading file line by line in Java using Scanner");

        while(scanner.hasNextLine()){
            System.out.println(scanner.nextLine());
        }

        scanner.close();
    }   

}

Output:
Reading file line by line in Java using Scanner
first line in file
second line
third line
fourth line
fifth line
last line in file

Answer 1

BufferedReader is a lot faster than Scanner because it buffers the character so you don’t have to access the file each time you want to read a char from it.

Scanner are of particular use such as reading primitive data type directly and is also used for regular expressions.

I have used Scanner and BufferedReader both and BufferedReader gives significant fast performance. You can test it yourself too.