Elegant way to read file into byte[] array in Java [duplicate]

A long time ago:

Call any of these

byte[] org.apache.commons.io.FileUtils.readFileToByteArray(File file)byte[] org.apache.commons.io.IOUtils.toByteArray(InputStream input) 

From

http://commons.apache.org/io/

If the library footprint is too big for your Android app, you can just use relevant classes from the commons-io library

Today (Java 7+ or Android API Level 26+)

Luckily, we now have a couple of convenience methods in the nio packages. For instance:

byte[] java.nio.file.Files.readAllBytes(Path path)

Javadoc here

This will also work:

import java.io.*;public class IOUtil {    public static byte[] readFile(String file) throws IOException {        return readFile(new File(file));    }    public static byte[] readFile(File file) throws IOException {        // Open file        RandomAccessFile f = new RandomAccessFile(file, "r");        try {            // Get and check length            long longlength = f.length();            int length = (int) longlength;            if (length != longlength)                throw new IOException("File size >= 2 GB");            // Read file and return data            byte[] data = new byte[length];            f.readFully(data);            return data;        } finally {            f.close();        }    }}

If you use Google Guava (and if you don't, you should), you can call: ByteStreams.toByteArray(InputStream) or Files.toByteArray(File)