Multithreading Vs. Asynchronous in Java

Creating stable and responsive apps in the dynamic world of Java development requires effective task management. Java concurrency can be achieved using asynchronous programming and multithreading.

Multithreading in Java

Programming's notion of multithreading allows for the simultaneous operation of several threads inside a single program. Writing programs that can handle numerous tasks at once is possible with Java. Each thread represents a separate flow of control. Key classes in Java for multithreading include Thread and Runnable.

Features of Multithreading

Parallel Execution: Several threads may run simultaneously and independently of one another.
Resource Sharing: When threads share a memory or other resources, it can cause problems with data synchronization.
Complexity: Because multithreaded code uses shared resources, writing it can be difficult and prone to errors.

Multithreading.java

class MyThread extends Thread {
    public void run() {
        for (int j = 1; j <= 3; j++) {
            System.out.println("Child Thread: " + j);
            try {
                Thread.sleep(1000); 
            } catch (InterruptedException e) {
                System.out.println(e);
            }
        }
    }
}
public class Multithreading {
    public static void main(String[] args) {
        MyThread thread = new MyThread();
        thread.start(); 
        for (int  t = 1; t <= 2; t++) {
            System.out.println("Main Thread: " + t);
            try {
                Thread.sleep(1000); 
            } catch (InterruptedException e) {
                System.out.println(e);
            }
        }
    }
}

Output:

Child Thread: 1
Main Thread: 1
Child Thread: 2
Main Thread: 2
Child Thread: 3

Asynchronous in Java

Asynchronous programming is a programming paradigm that permits task execution to occur independently of the main program flow. The CompletableFuture class is available in Java for asynchronous programming.

Features of Asynchronous Programming:

Non-Blocking: The main program's execution is not impeded by asynchronous code.
Callback Mechanism: Handles outcomes after the task is finished using callbacks or futures.
Concurrency without Threads: This method accomplishes concurrency without using numerous threads.

Asynchronous.java

import java.util.concurrent.CompletableFuture;
public class Asynchronous {
    public static void main(String[] args) {
        CompletableFuture<Void> future = CompletableFuture.runAsync(() -> {
            for (int r = 1; r <= 5; r++) {
                System.out.println("Asynchronous Task: " + r);
                try {
                    Thread.sleep(500); 
                } catch (InterruptedException e) {
                    System.out.println(e);
                }
            }
        });
        // Code in the main thread, not blocked by the asynchronous task
        System.out.println("Main Thread: Doing other work");
        future.join(); // Wait for the asynchronous task to complete if needed
    }
}

Output:

Main Thread: Doing other work
Asynchronous Task: 1
Asynchronous Task: 2
Asynchronous Task: 3
Asynchronous Task: 4
Asynchronous Task: 5

Difference Between Multithreading and Asynchronous in Java

Feature	Multithreading	Asynchronous Programming
Concurrency Model	Parallel execution of threads.	Non-blocking execution of tasks.
Resource Sharing	Shared memory space, potential for conflicts.	Separate memory space, reduced conflicts.
Complexity	More complex due to shared resources.	Simplified, avoids many synchronization issues.
Performance	May be resource-intensive due to thread creation and management.	Efficient resource usage.
Programming Model	Threads explicitly created and managed.	Uses features like CompletableFuture for asynchronous programming.
Error Handling	Difficult to manage errors across threads.	Easier error handling with CompletableFuture.
Context Switching	Involves context switching between threads, incurring potential overhead.	Typically involves less context switching overhead.
Scalability	Can face scalability challenges with a large number of threads.	Generally scales better, suitable for a large number of concurrent tasks.
Deadlocks and Race Conditions	Prone to deadlocks and race conditions with shared resources.	Reduces the likelihood of deadlocks and race conditions.
Debugging Complexity	Debugging can be complex due to shared resources and multiple threads.	Offers more straightforward debugging and identification of issues.
Task Independence	Threads may share resources, leading to dependencies.	Tasks are often independent, reducing dependencies.
Task Coordination	Requires explicit coordination mechanisms like wait, notify, and join.	Coordination is often implicit, utilizing callbacks, futures, and promises.
Blocking Operations	Blocking operations may lead to thread contention and delays.	Non-blocking operations, reducing contention and improving responsiveness.
Resource Utilization	Resource-intensive due to the potential creation of many threads.	Efficient resource utilization, suitable for scenarios with limited resources.
User Interface (UI) Thread	Common for UI applications, may lead to unresponsive interfaces.	Well-suited for UI applications, as it avoids blocking the UI thread.
Flexibility	Offers fine-grained control over thread creation and execution.	Provides a more flexible and high-level abstraction with CompletableFuture.
Library Support	Traditional thread-related classes like Thread and ExecutorService.	Modern APIs like CompletableFuture and reactive programming libraries.
Compatibility	Widely compatible with older Java versions.	Requires Java 8 or later for comprehensive support of CompletableFuture.
Task Cancelation	Limited support for canceling individual tasks.	Supports cancelation of asynchronous tasks through CompletableFuture.cancel().
Wait and Notify	Utilizes wait and notify for inter-thread communication.	Often relies on callback mechanisms and the completion of futures.
Blocking vs. Non-blocking	More inclined towards blocking operations.	Primarily employs non-blocking operations for better responsiveness.
Ease of Learning	It may have a steeper learning curve, especially for beginners.	More approachable and intuitive, making it easier to grasp for some developers.