FileInputStream & FileOutputStream

The File class from the previous lesson reports that a file exists, where it lives, and how big it is. It does not read or write a single byte of its contents. For that, Java's java.io package provides a pair of low-level classes that treat a file as a raw sequence of bytes: FileInputStream for reading and FileOutputStream for writing. This lesson covers what byte streams are, when to use them, and how to read and write binary data like product images, inventory snapshots, and order blobs without corrupting them.