Java BufferedReader and FileReader example read text file

Using Java BufferedReader and FileReader to open a text file and read the contents of it :

In this example, I will show you one basic Java File I/O operation : “Reading the contents” of a text file. We will use ‘BufferedReader’ and ‘FileReader’ class in this example. What these classes are used to do mainly ?

Let’s check.

BufferedReader :

BufferedReader is used to read text from a input stream. It buffers the input reading for more efficiency. Without buffering , reading operations will become more time consuming.

FileReader :

FileReader is used mainly for reading character file. We will use one ‘FileReader’ wrapped with a ‘BufferedReader’. The read() operation of ‘FileReader’ is costly. So if we wrap it with ‘BufferedReader’ , it will buffer the inputs and make the process more smoother.

Let’s take a look into the Java Program :

Java Program to read contents of a text file :

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.util.ArrayList;
import java.util.Scanner;

public class Main {

    /**
     * Utility function to print
     */
    static void print(String string) {
        System.out.print(string);
    }


    public static void main(String[] args) {
        ArrayList readingLines = new ArrayList<>(); //1
        String line;
        try {
            FileReader fileReader = new FileReader("in.txt"); //2

            BufferedReader bufferedReader = new BufferedReader(fileReader); //3
            while ((line = bufferedReader.readLine()) != null) {
                readingLines.add(line); //4
            }

            bufferedReader.close();

            for (int i = 0; i < readingLines.size(); i++) {
                print(readingLines.get(i));
            }

        } catch (Exception e) {

        }
    }
}

How this program works :

First create one ArrayList of String to store the contents of the file.
Create one FileReader object by passing the file location to its constructor.
Wrapped this FileReader object with a BufferedReader.
Now use one while loop, to read lines from the file. And store it in a variable line.
After while loop is completed , close the BufferedReader.
Finally, to print the contents, simply use one ‘for’ loop to print out the contents of the ArrayList readingLines.

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