Here, we will go through the different ways to convert file to byte array in Java.
Note: Keep a check that prior doing anything first. Create a file on the system repository to deal with our program\writing a program as we will be accessing the same directory through our programs.
Methods:
- Using read(byte[]) method of FileInputStream class
- Using Files.readAllBytes() method
Method 1: Using read(byte[]) method of FileInputStream class
FileInputStream is useful to read data from a file in the form of a sequence of bytes. FileInputStream is meant for reading streams of raw bytes such as image data. For reading streams of characters, consider using FileReader. read(byte[]) method of FileInputStream class which reads up to the length of the file and then converts bytes of data from this input stream into the byte array.
Procedure:
- Create an instance of File Input Stream with the file path.
- Create a byte array of the same length as the file.
- Read that file content to an array.
- Print the byte array.
- Close the instance of the file input stream as it is a good practice in order to avoid any exception or error being faced during runtime and to release the memory resources making our program optimized leading to faster execution.
Implementation: In order to illustrate the conversion of a text file present in the local directory on a machine to the byte array, we will be considering a random file named say it be ‘demo.rtf’ which is present in the local directory.
Example:
Java
// Java Program to Convert File to a Byte Array// Using read(byte[]) Method // Importing required classesimport java.io.*;import java.io.File;import java.io.FileInputStream;import java.io.IOException;import java.util.Arrays; // Main classpublic class GFG { // Method 1 // To convert file to byte array public static byte[] method(File file) throws IOException { // Creating an object of FileInputStream to // read from a file FileInputStream fl = new FileInputStream(file); // Now creating byte array of same length as file byte[] arr = new byte[(int)file.length()]; // Reading file content to byte array // using standard read() method fl.read(arr); // lastly closing an instance of file input stream // to avoid memory leakage fl.close(); // Returning above byte array return arr; } // Method 2 // Main driver method public static void main(String[] args) throws IOException { // Creating an object of File class and // providing local directory path of a file File path = new File( "/Users/mayanksolanki/Desktop/demo.rtf"); // Calling the Method1 in main() to // convert file to byte array byte[] array = method(path); // Printing the byte array System.out.print(Arrays.toString(array)); }} |
Output:
Method 2: Using readAllBytes() method of Files class
java.nio.file.Files class has pre-defined readAllBytes() method which reads all the bytes from a file.
Procedure:
- Take a text file path
- Convert that file into a byte array by calling Files.readAllBytes().
- Print the byte array.
Example:
Java
// Java Program to Convert File to a Byte Array// Using Files.readAllBytes() Method // Importing required classesimport java.io.*;import java.io.IOException;import java.nio.file.Files;import java.nio.file.Path;import java.nio.file.Paths;import java.util.Arrays; // Main classpublic class GFG { // Main driver method public static void main(String[] args) throws IOException { // Creating an object of Path class and // assigning local directory path of file to it Path path = Paths.get( "/Users/mayanksolanki/Desktop/demo.rtf"); // Converting the file into a byte array // using Files.readAllBytes() method byte[] arr = Files.readAllBytes(path); // Printing the above byte array System.out.println(Arrays.toString(arr)); }} |
Output:
