Get file size in bytes in Java

This post will discuss how to get file size in bytes in Java.

1. Using `File#length()` method

A simple solution is to call the File#length() method that returns the size of the file in bytes. To get the file size in MB, you can divide the length (in bytes) by 1024 * 1024. Note that the File#length() method returns length 0 if the file is a directory, or an I/O exception occurred.

import java.io.File;

public class Main {

public static void main(String[] args) {

File file = new File("/var/system.logs");

long size = file.length();

System.out.println("The file size is " + size + " bytes");

}

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2. Using `Files.size()` method

Java NIO Files class provides several utility methods for operations on files. To get the size of a file in bytes, you can use the Files.size() method. Note that the actual file size might be different, due to compression, support for sparse files, or other reasons.

import java.io.IOException;

import java.nio.file.Files;

import java.nio.file.Path;

public class Main {

public static void main(String[] args) {

String filePath = "/var/system.logs";

try {

long size = Files.size(Path.of(filePath));

System.out.println("The file size is " + size + " bytes");

} catch (IOException e) {

e.printStackTrace();

}

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3. Using `FileChannel#size()` method

Another option is to obtain a file input stream for the file in a file system and get the associated file channel. Then you can use the size() method that returns the current size of the channel’s file, measured in bytes.

import java.io.File;

import java.io.FileInputStream;

import java.io.IOException;

public class Main {

public static void main(String[] args) {

String filePath = "/var/system.logs";

try (FileInputStream fis = new FileInputStream(new File(filePath))) {

long size = fis.getChannel().size();

System.out.println("The file size is " + size + " bytes");

} catch (IOException e) {

e.printStackTrace();

}

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That’s all about getting file size in bytes in Java.

Get file size in bytes in Java

1. Using File#length() method

2. Using Files.size() method

3. Using FileChannel#size() method

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1. Using `File#length()` method

2. Using `Files.size()` method

3. Using `FileChannel#size()` method