In Java, the FileInputStream and FileOutputStream classes are used for reading from and writing to files, respectively. They provide a way to interact with binary data in files, allowing you to read bytes from a file or write bytes to a file.

The FileInputStream class is used to open a connection to a file and read data from it. It inherits from the InputStream class and provides methods like read() to read bytes from the file. You can read data in chunks or individual bytes, depending on your requirements. This class is commonly used for tasks such as reading images, audio files, or any other binary data stored in a file.

Here’s an example of using FileInputStream to read data from a file:

<span class="hljs-keyword">try</span> {
<span class="hljs-type">FileInputStream</span> <span class="hljs-variable">inputStream</span> <span class="hljs-operator">=</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">FileInputStream</span>(<span class="hljs-string">"input.txt"</span>);
<span class="hljs-type">int</span> data;
<span class="hljs-keyword">while</span> ((data = inputStream.read()) != -<span class="hljs-number">1</span>) {
<span class="hljs-comment">// Process the data</span>
System.out.print((<span class="hljs-type">char</span>) data);
}
inputStream.close();
} <span class="hljs-keyword">catch</span> (IOException e) {
e.printStackTrace();
}


The FileOutputStream class, on the other hand, is used to create an output stream that you can use to write data to a file. It inherits from the OutputStream class and provides methods like write() to write bytes to the file. You can write data in chunks or individual bytes, depending on your requirements. This class is commonly used for tasks such as saving binary data or generating files dynamically.

Here’s an example of using FileOutputStream to write data to a file:

<span class="hljs-keyword">try</span> {
<span class="hljs-type">FileOutputStream</span> <span class="hljs-variable">outputStream</span> <span class="hljs-operator">=</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">FileOutputStream</span>(<span class="hljs-string">"output.txt"</span>);
<span class="hljs-type">String</span> <span class="hljs-variable">data</span> <span class="hljs-operator">=</span> <span class="hljs-string">"Hello, World!"</span>;
outputStream.write(data.getBytes());
outputStream.close();
} <span class="hljs-keyword">catch</span> (IOException e) {
e.printStackTrace();
}


In both examples, it’s important to close the streams after you’re done using them. This ensures that system resources are freed up and the file is properly closed.

Using FileInputStream and FileOutputStream, you can read and write binary data to files, giving you the ability to handle file-based operations in your Java programs.