Implementing an asynchronous data processing pipeline

You're building an analytics dashboard that needs to fetch user data and activity logs from separate services, then process them to create a user summary. This operation should be performed asynchronously to keep your application responsive. You are tasked to implement this using CompletableFuture.

The UserData and UserSummary classes have been preloaded for you.

This exercise is part of the course

Optimizing Code in Java

View Course

Exercise instructions

Add fetching user data in the CompletableFuture.
Add processing user data in the CompletableFuture.
Add exception handling in the CompletableFuture.

Hands-on interactive exercise

Have a go at this exercise by completing this sample code.

public class AsyncDashboard {
    public static void main(String[] args) throws Exception {        
        CompletableFuture userSummaryFuture = CompletableFuture
            // Fetch the user data
            .____(() -> fetchUserData("user123"))
            
            // Create summary based on fetched data
            .____(userData -> createSummary(userData))
            
            // Add exception handling
            .____(ex -> new UserSummary(new UserData("error", "Error User"))); 
        Thread.sleep(5000);
    }
    
    private static UserData fetchUserData(String userId) {
        simulateNetworkLatency(300);
        return new UserData(userId, "John Doe");
    }
    
    private static UserSummary createSummary(UserData userData) {
        simulateNetworkLatency(200);
        return new UserSummary(userData);
    }
    
    private static void simulateNetworkLatency(int millis) {
        try { Thread.sleep(millis); } catch (InterruptedException e) {}
    }
}

Edit and Run Code