How to find length of given file in Java?

Problem Description :

Write a program in Java that finds the length of given file.

How to find the length of given file in Java?

Concept :

We need to use following method of File class that is present in java.io.* package.

public long length()

Java Program :

	package com.javamultiplex.FileHandling;
	import java.io.File;
	import java.io.IOException;
	import java.util.Scanner;
	/**
	*
	* @author Rohit Agarwal
	* @category File Handling
	* @problem How to find length of given file in Java?
	*
	*/
	public class LengthFinder {
	public static void main(String[] args) throws IOException {
	Scanner input = null;
	try {
	input = new Scanner(System.in);
	System.out.println("Enter file name with extension : ");
	String fileName = input.nextLine();
	if (isValidFileName(fileName)) {
	// File is present in current working directory.
	File file = new File(fileName);
	long length = file.length();
	System.out.println("Length of file is : " + length + " bytes.");
	} else {
	System.out.println("File name is invalid.");
	}
	} finally {
	if (input != null) {
	input.close();
	}
	}
	}
	private static boolean isValidFileName(String fileName) {
	// Regular expression for validating file name.
	String pattern = "^.+\\..+$";
	boolean result = false;
	if (fileName.matches(pattern)) {
	result = true;
	}
	return result;
	}
	}

view raw LengthFinder.java hosted with ❤ by GitHub

Output :

Output - How to find the length of given file in Java?

Demo of file length finder

References :

https://docs.oracle.com/javase/7/docs/api/java/io/File.html

https://docs.oracle.com/javase/7/docs/api/java/io/File.html#length()

https://en.wikipedia.org/wiki/Regular_expression

Thank you friends, I hope you have clearly understood the solution of this problem. If you have any doubt, suggestion or query please feel free to comment below. You can also discuss this solution in our forum.

Tags : File Handling, file length finder, if else, Scanner, String, File, Regular expression, length(), java.io.

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