Any object representing a mutable data source in Java exposes methods for reading and writing its data as a stream. Java.io is the main package for most stream-oriented I/O classes.

Abstract classes and interfaces in Java serve fundamentally different purposes. Learn the differences between these Java language elements and how to use them in your programs.

Java 23, now generally available, includes previews of module import declarations, stream gatherers, structured concurrency, scoped values, and a class-file API. And much more.