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Ilias is a software developer turned online entrepreneur. He is co-founder and Executive Editor at Java Code Geeks.

Write String as bytes to file with DataOutputStream

In this example we shall show you how to write a String as bytes to file with the DataOutputStream. The DataOutputStream lets an application write primitive Java data types to an output stream in a portable way. An application can then use a data input stream to read the data back in. To write a String as bytes to file with the DataOutputStream one should perform the following steps:

  • Create a FileOutputStream to write to the file with the specified name.
  • Create a DataOutputStream with the FileOutputStream.
  • Use writeBytes(String s) API method. It writes out the string to the underlying output stream as a sequence of bytes,

as described in the code snippet below.

package com.javacodegeeks.snippets.core;

import java.io.DataOutputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

public class WriteStringAsBytesToFileWithDataOutputStream {
	public static void main(String[] args) {
		String filename = "output.txt";
		String output = "Java Code Geeks - Java Examples";
		FileOutputStream fos = null;
		DataOutputStream dos = null;

		try {
			fos = new FileOutputStream(filename);
			dos = new DataOutputStream(fos);
		catch (FileNotFoundException fnfe) {
			System.out.println("File not found" + fnfe);
		catch (IOException ioe) {
			System.out.println("Error while writing to file" + ioe);
		finally {
			try {
				if (dos != null) {
				if (fos != null) {
			catch (Exception e) {
				System.out.println("Error while closing streams" + e);

This was an example of how to write a String as bytes to file with the DataOutputStream in Java.

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