Java 11: handling when using CompletableFuture with Retry Logic on HTTP Requests
I'm wondering if anyone has experience with I tried several approaches but none seem to work. After trying multiple solutions online, I still can't figure this out. I'm working with an scenario while implementing a retry mechanism using `CompletableFuture` for making HTTP requests in Java 11. The goal is to retry failed requests a couple of times before giving up, but I keep receiving a `java.util.concurrent.CompletionException` with a nested `java.net.UnknownHostException` for failed requests. I want to ensure that if a request fails due to a transient network scenario, it retries correctly. Here’s a simplified version of my implementation: ```java import java.net.HttpURLConnection; import java.net.URL; import java.util.concurrent.CompletableFuture; import java.util.concurrent.ExecutionException; public class HttpClient { public CompletableFuture<String> makeRequest(String url) { return CompletableFuture.supplyAsync(() -> { try { HttpURLConnection connection = (HttpURLConnection) new URL(url).openConnection(); connection.setRequestMethod("GET"); return String.valueOf(connection.getResponseCode()); } catch (Exception e) { throw new CompletionException(e); } }); } public CompletableFuture<String> makeRequestWithRetry(String url, int retries) { return makeRequest(url).handle((result, throwable) -> { if (throwable != null && retries > 0) { System.out.println("Request failed, retrying... Remaining attempts: " + (retries - 1)); return makeRequestWithRetry(url, retries - 1).join(); } else if (throwable != null) { throw new RuntimeException(throwable); } return result; }); } } ``` When I run the following test: ```java public class Main { public static void main(String[] args) throws ExecutionException, InterruptedException { HttpClient client = new HttpClient(); String response = client.makeRequestWithRetry("http://invalid-url.com", 3).get(); System.out.println("Response Code: " + response); } } ``` I receive the following behavior: `java.util.concurrent.CompletionException: java.net.UnknownHostException: invalid-url.com`. I suspect the scenario might be due to how I'm handling the exceptions and the nested futures. I'm also unsure if using `join()` in the `handle` method is the right approach. I've tried using `thenCompose`, but I couldn't get it to work as intended. Any suggestions on how to properly implement this retry logic with behavior handling for transient failures? What's the best practice here? This is part of a larger service I'm building. Any ideas what could be causing this? Thanks, I really appreciate it!