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Java get file size

Published on August 3, 2022
Default avatar
By Pankaj
Developer and author at DigitalOcean.
Java get file size

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Today we will look into different ways to get file size in Java.

Java get file size

There are different classes that we can use for java get file size program. Some of them are;

  1. Java get file size using File class
  2. Get file size in java using FileChannel class
  3. Java get file size using Apache Commons IO FileUtils class

Before we look into an example program to get file size, we have a sample pdf file with size 2969575 bytes. java file size, java get file size

Java get file size using File class

Java File length() method returns the file size in bytes. The return value is unspecified if this file denotes a directory. So before calling this method to get file size in java, make sure file exists and it’s not a directory. Below is a simple java get file size example program using File class.

package com.journaldev.getfilesize;

import java.io.File;

public class JavaGetFileSize {

	static final String FILE_NAME = "/Users/pankaj/Downloads/file.pdf";

	public static void main(String[] args) {
		File file = new File(FILE_NAME);
		if (!file.exists() || !file.isFile()) return;

		System.out.println(getFileSizeBytes(file));
		System.out.println(getFileSizeKiloBytes(file));
		System.out.println(getFileSizeMegaBytes(file));
	}

	private static String getFileSizeMegaBytes(File file) {
		return (double) file.length() / (1024 * 1024) + " mb";
	}
	
	private static String getFileSizeKiloBytes(File file) {
		return (double) file.length() / 1024 + "  kb";
	}

	private static String getFileSizeBytes(File file) {
		return file.length() + " bytes";
	}
}

java get file size

Get file size in java using FileChannel class

We can use FileChannel size() method to get file size in bytes.

package com.journaldev.getfilesize;

import java.io.IOException;
import java.nio.channels.FileChannel;
import java.nio.file.Path;
import java.nio.file.Paths;

public class JavaGetFileSizeUsingFileChannel {

	static final String FILE_NAME = "/Users/pankaj/Downloads/file.pdf";

	public static void main(String[] args) {

		Path filePath = Paths.get(FILE_NAME);
		FileChannel fileChannel;
		try {
			fileChannel = FileChannel.open(filePath);
			long fileSize = fileChannel.size();
			System.out.println(fileSize + " bytes");
			fileChannel.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

Java get file size using Apache Commons IO FileUtils class

If you are already using Apache Commons IO in your project, then you can use FileUtils sizeOf method to get file size in java.

package com.journaldev.getfilesize;

import java.io.File;

import org.apache.commons.io.FileUtils;

public class JavaGetFileSizeUsingApacheCommonsIO {

	static final String FILE_NAME = "/Users/pankaj/Downloads/file.pdf";

	public static void main(String[] args) {
		File file = new File(FILE_NAME);

		long fileSize = FileUtils.sizeOf(file);

		System.out.println(fileSize + " bytes");
	}
}

That’s all for java get file size programs.

You can checkout more Java IO examples from our GitHub Repository.


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About the authors
Default avatar
Pankaj

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Developer and author at DigitalOcean.

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Was this helpful?

Thanks for the code, helped me in my assignment

- Mukta

    About File vs FileUtils vs FileChannel: Is there any reason to choose one above the other or is it just that people choose whatever they like?

    - Arjan

      Iam sending pdf filename to java through ajax call.While saving that filename in a folder it showing only filename content is not displaying.

      - test1234