completablefuture usage guide

CompletableFuture Usage: A Comprehensive Guide

1. How does CompletableFuture handle the concurrency of asynchronous tasks?

CompletableFuture uses a thread pool to manage the concurrency of asynchronous tasks. When a CompletableFuture is created, it is automatically associated with a default or custom thread pool that is responsible for performing asynchronous operations.

For multiple asynchronous tasks that need to be executed in parallel, CompletableFuture provides join() and allOf() methods. The join() method waits for all associated tasks to complete, while the allOf() method returns a CompletableFuture that completes after all associated tasks complete.

2. How to build a composable asynchronous pipeline through CompletableFuture?

The thenCompose() and thenAcceptBoth() methods of CompletableFuture provide a mechanism for combining asynchronous calls. The thenCompose() method takes the result of the current CompletableFuture as a parameter of the function and returns a new CompletableFuture. This feature allows asynchronous tasks to be chained together to form a pipeline.

3. What are the comparisons and advantages of CompletableFuture and Future?

CompletableFuture is a more modern implementation of Future introduced in Java 8. It provides the following advantages:

• Composability: The thenCompose() and thenAcceptBoth() methods of CompletableFuture allow the construction of composable asynchronous pipelines.
• Cancellation support: CompletableFuture supports cancellation operations, allowing unfinished asynchronous tasks to be explicitly terminated.
• Exception handling: CompletableFuture provides dedicated methods for handling exceptions, such as the exceptionally() and handle() methods.

4. Example usage of CompletableFuture

CompletableFuture<Integer> future = CompletableFuture.supplyAsync(() -> {
    return 10;
});

future.thenAccept(result -> {
    System.out.println("Result: " + result);
});

In this example, CompletableFuture is used to asynchronously calculate an integer value. The thenAccept() method specifies a callback function that handles the result. When the asynchronous operation completes, this function will be called and the result will be printed.

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