What is the Stream API in Java?

The Stream API in Java is a powerful feature introduced in Java 8 that enables developers to process sequences of elements in a functional style. This API provides a new way to work with collections and other data sources, allowing for more expressive and concise code. Instead of writing loops to iterate over collections, the Stream API allows you to focus on what you want to achieve rather than how you achieve it.

One of the key advantages of the Stream API is its ability to support operations like filtering, mapping, and reducing in a declarative manner. These operations can be chained together to create a pipeline of data processing steps, which can be executed efficiently. The Stream API also supports lazy evaluation, meaning that intermediate operations are not executed until a terminal operation, such as collect() or forEach(), is invoked.

The Stream API also allows for parallel processing, which can improve performance on multi-core systems. By simply using a parallel stream, you can take advantage of parallelism without the need to manage threads explicitly. This makes the Stream API a powerful tool for writing clean, efficient, and maintainable code in Java.