Convert File to a Byte Array in Java

1. Use readAllBytes() to Convert a File to Byte Array in Java
2. Use FileUtils.readFileToByteArray() to Convert a File to Byte Array in Java

This tutorial discusses methods to convert a file to byte array in Java.

Use readAllBytes() to Convert a File to Byte Array in Java

The simplest way to convert a file to byte array in Java is to use the readAllBytes() method provided by the Files class. In the example below, we will first read a file and then convert it to a byte array.

import java.io.File;
import java.nio.file.Files;
import java.nio.file.Path;

public class MyClass {
    public static void main(String args[]) throws IOException {
        File file = new File('sample.txt')
        byte[] fileContent = Files.readAllBytes(file.toPath());
    }
}

Use FileUtils.readFileToByteArray() to Convert a File to Byte Array in Java

Another method to convert a file to byte array in Java is to use FileUtils.readFileToByteArray() provided by Apache Commons File Utils. The below example illustrates this:

import org.apache.commons.io.FileUtils;

public class MyClass {
    public static void main(String[] args) throws IOException {
        File file = new File('sample.txt');
        byte[] fileContent = FileUtils.readFileToByteArray(file);
    }
}