Java FileOutputStream Class

The FileOutputStream class in Java is used to write byte data to a file. In this chapter, we will learn what the FileOutputStream class is, when to use it, its methods, and how to write data to a file using simple examples.

What is FileOutputStream in Java?

The FileOutputStream class is an output stream used to write data into a file. It writes data in the form of bytes and is mainly used for byte-oriented file operations.

If you want to write primitive or binary data into a file, the FileOutputStream class is suitable. Although it can also write character data, it is recommended to use the FileWriter class for character-oriented operations.

FileOutputStream class declaration

The following declaration shows how the FileOutputStream class is defined:

Constructors of FileOutputStream Class

The FileOutputStream class provides constructors to create an output stream and connect it to a file.

1. FileOutputStream(String name)

This constructor creates a file output stream to write data to a file with the specified name. If the file already exists, its content is overwritten. If the file does not exist, a new file is created.

Syntax:

Here is the syntax of this constructor:

2. FileOutputStream(String name, boolean append)

This constructor creates a file output stream to write data to a file. If append is set to true, the data is added at the end of the file. If it is false, the existing file content is overwritten.

Syntax:

Here is the syntax of this constructor:

3. FileOutputStream(File file)

This constructor creates a file output stream using a File object instead of a file name.

Syntax:

Here is the syntax of this constructor:

4. FileOutputStream(File file, boolean append)

This constructor creates a file output stream using a File object and allows appending data to the file if required.

Syntax:

Here is the syntax of this constructor:

Example: Using FileOutputStream Constructor with Append Mode

The following example demonstrates how to append data to an existing file using the FileOutputStream constructor.

Output:

data appended successfully

Methods of FileOutputStream Class

The FileOutputStream class provides several methods to write data to a file.

Example 1: Writing a Single Byte Using FileOutputStream

In this example, a single byte value is written to a file. The byte value 65 represents the character A.

Output:

Success...

The content of a text file testout.txt is set with the data A.

testout.txt

A

Example 2: Writing a String Using FileOutputStream

In this example, a string is converted into a byte array and then written to a file using the FileOutputStream class.

Output:

Success...

The content of a text file testout.txt is set with the data Welcome to javaTpoint.

testout.txt

Welcome to javaTpoint.