Read byte array from file with DataInputStream

With this example we are going to demonstrate how to read a byte array from a file with the DataInputStream. The DataInputStream lets an application read primitive Java data types from an underlying input stream in a machine-independent way. In short, to read a byte array from a file with the DataInputStream you should:

  • Create a FileInputStream by opening a connection to an actual file, the file named by the path name name in the file system.
  • Create a DataInputStream with the FileInputStream.
  • Use read(byte[] b) API method. It reads the given byte array.

Let’s take a look at the code snippet that follows:

package com.javacodegeeks.snippets.core;


public class ReadByteArrayFromFileWithDataInputStream {
	public static void main(String[] args) {
		String filename = "input.txt";
		FileInputStream fis = null;
		DataInputStream dis = null;		

		try {
			fis = new FileInputStream(filename);

			dis = new DataInputStream(fis);

			byte b[] = new byte[10];;

		catch (FileNotFoundException fe) {
			System.out.println("File not found: " + fe);
		catch (IOException ioe) {
			System.out.println("Error while reading file: " + ioe);
		finally {
			try {
				if (dis != null) {
				if (fis != null) {
			catch (Exception e) {
				System.out.println("Error while closing streams" + e);

This was an example of how to read a byte array from a file with the DataInputStream in Java.

Byron Kiourtzoglou

Byron is a master software engineer working in the IT and Telecom domains. He is an applications developer in a wide variety of applications/services. He is currently acting as the team leader and technical architect for a proprietary service creation and integration platform for both the IT and Telecom industries in addition to a in-house big data real-time analytics solution. He is always fascinated by SOA, middleware services and mobile development. Byron is co-founder and Executive Editor at Java Code Geeks.
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