What is the purpose of the CompletableFuture class in Java and in what scenarios is it usually used?

The CompletableFuture class in Java is an enhanced implementation of the Future interface, allowing for more flexible and convenient handling of asynchronous computations.

Main features and purposes:

• Enables launching asynchronous tasks and obtaining results in the future.
• Supports chaining, which simplifies result and error handling.
• Allows combining multiple asynchronous operations (e.g., thenCombine, thenCompose).
• Provides convenient methods for exception handling.

Typical use cases:

• Executing long-running operations asynchronously (database queries, network calls).
• Parallel data processing with subsequent result aggregation.
• Implementing reactive and non-blocking applications.

Example usage:

CompletableFuture.supplyAsync(() -> {
    // Long operation
    return "Result";
}).thenApply(result -> {
    // Process result
    return result.toUpperCase();
}).thenAccept(finalResult -> {
    System.out.println(finalResult);
});

Thus, CompletableFuture significantly simplifies working with asynchrony in Java.