Error Handling and Async HTTP Pipeline
Handle errors with exceptionally, handle, and whenComplete, then build an async HTTP client pipeline.
Why Async Error Handling Matters
In async pipelines, exceptions don't propagate the same way as in synchronous code. You must explicitly handle errors using exceptionally, handle, or whenComplete.
exceptionally: Recovering From Errors
exceptionally(Function<Throwable, T>) is called only if the future completes with an exception. It provides a fallback value, keeping the pipeline alive.
CompletableFuture<String> safe = fetchUser(id)
.thenApply(User::getName)
.exceptionally(ex -> {
log.warn("Fetch failed: " + ex.getMessage());
return "Anonymous";
});
System.out.println(safe.join()); // "Anonymous" if fetch failedAll lessons in this course
- Creating and Completing CompletableFutures
- Chaining with thenApply and thenCompose
- Combining Futures: allOf and anyOf
- Error Handling and Async HTTP Pipeline