Since we are very familiar with this topic, we put more emphasis on finding the small differences between them. Here we have to read from a file in the local directory which has a text file, for example "gfg.txt". Make the contents of the file look like this:

Geeks for Geeks.
A computer science portal.
Welcome to this portal.
Hello Geek !!!

Note: Keep a check that prior doing anything first create a file on the system repository to deal with our program\writing a program as we will be accessing the same directory through our programs.

Methods:

1. Using Scanner class
2. Using BufferedReaader class

Method 1: Using Scanner class

Scanner is a class in the java.util package, used to obtain primitive types (such as int, double, etc.) and string input. This is the easiest way to read input in a Java program, but if you want an input method for time-constrained scenarios (such as competitive programming), it is not efficient. The Scanner class is used to read large files line by line. Scanner breaks its input into tokens, which match spaces by default.

Example

// Java Program to Read a Large Text File Line by Line
// Using Scanner class

// Importing required classes
import java.io.*;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;
import java.util.Scanner;

// Main class
public class GFG {

	// Main driver method
	public static void main(String[] args)
		throws FileNotFoundException
	{

		// Declaring and initializing the string with
		// custom path of a file
		String path = "C:\\Users\\HP\\Desktop\\gfg.txt";

		// Creating an instance of Inputstream
		InputStream is = new FileInputStream(path);

		// Try block to check for exceptions
		try (Scanner sc = new Scanner(
				is, StandardCharsets.UTF_8.name())) {

			// It holds true till there is single element
			// left in the object with usage of hasNext()
			// method
			while (sc.hasNextLine()) {

				// Printing the content of file
				System.out.println(sc.nextLine());
			}
		}
	}
}

Output: 

Geeks for Geeks.
A computer science portal.
Welcome to this portal.
Hello Geek !!!

Method 2: Using BufferedReader class

BufferedReader is used to read the file line by line. In general, BufferedReader() is used to process large files. BufferedReader is very efficient to read.

Note: Specify the size of the BufferReader or keep that size as a Default size of BufferReader. The default size of BufferReader is 8KB. 

Syntax:

BufferedReader in = new BufferedReader(Reader in, int size);

Example:

// Java Program to Read a Large Text File Line by Line
// Using BufferedReader class

// Importing required classes
import java.io.*;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

// Main class
public class GFG {

	// Main driver method
	public static void main(String[] args)
	{

		// Declaring a string and initializing it with
		// path of file present on the system
		String path = "C:\\Users\\HP\\Desktop\\gfg.txt";

		// Try block to check for exceptions
		try (BufferedReader br
			= new BufferedReader(new FileReader(path))) {

			// Declaring a new string
			String str;

			// It holds true till threre is content in file
			while ((str = br.readLine()) != null) {

				// Printing the file data
				System.out.println(br);
			}
		}

		// Catch block to handle the exceptions
		catch (IOException e) {

			// Display pop up message if exceptionn occurs
			System.out.println(
				"Error while reading a file.");
		}
	}
}

Output: 

Geeks for Geeks.
A computer science portal.
Welcome to this portal.
Hello Geek !!!