What is async in java interview questions

What is async in java interview questions

I'd be happy to help you with that!

In Java, "async" refers to asynchronous programming, which allows your program to perform multiple tasks simultaneously without blocking the main thread. In traditional synchronous programming, when you call a method or make an API request, the program waits for the response before continuing with the next task.

Async programming in Java is typically achieved using libraries and frameworks such as:

In a typical async scenario in Java, you'd:

Some common interview questions related to async programming in Java include:

You should use try-catch blocks and exception handlers, just as you would in synchronous code. However, since async code can be more complex, it's essential to consider how exceptions will propagate through the call stack.

Some potential issues include:

To achieve optimal performance, consider:

In brief: A Callable is a task that returns a value when completed, while a Future represents the result of such a task. When you call a Callable, it's like starting an async operation; when you get a Future, you can check its status (e.g., complete or pending) and retrieve the result if it has completed.

You should use mechanisms such as Cancelables or CompletableFutures to control the cancellation process. It's crucial to ensure that your code handles both successful completion and cancellation scenarios correctly.

These are just a few examples of the types of questions you might encounter when discussing async programming in Java. Remember to be prepared to talk about best practices, common pitfalls, and optimization strategies for writing effective asynchronous code!

Asynchronous call in Java Spring Boot

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Asynchronous calls in Java Spring Boot can be achieved using various techniques, such as:

public class MyService {
public String asynchronousCall() {
ForkJoinPool pool = new ForkJoinPool();
MyCallable task = new MyCallable();
Future future = pool.submit(task);
try {
return future.get(); // blocks until the computation completes
} catch (InterruptedException | ExecutionException e) {
throw new RuntimeException(e);
}
}
}
class MyCallable implements Callable {
@Override
public String call() {
// Your long-running task goes here
return "Hello from MyCallable!";
}
}

@Service
public class MyService {
@Async
public void asynchronousCall() {
// Your long-running task goes here
System.out.println("Hello from asynchronousCall!");
}
}

public class MyService {
public String asynchronousCall() {
Executor executor = Executors.newSingleThreadExecutor();
Callable callable = new MyCallable();
Future future = executor.submit(callable);
try {
return future.get(); // blocks until the computation completes
} catch (InterruptedException | ExecutionException e) {
throw new RuntimeException(e);
}
}
}
class MyCallable implements Callable {
@Override
public String call() {
// Your long-running task goes here
return "Hello from MyCallable!";
}
}

public class MyService {
public String asynchronousCall() {
CompletableFuture future = CompletableFuture.supplyAsync(() -> {
// Your long-running task goes here
return "Hello from CompletableFuture!";
});
try {
return future.get(); // blocks until the computation completes
} catch (InterruptedException | ExecutionException e) {
throw new RuntimeException(e);
}
}
}

When dealing with Spring Boot, you can use the @Async annotation on a method to enable asynchronous execution. This is especially useful when handling requests that require long-running computations.

For example:

@RestController
public class MyController {
@Autowired
private AsyncService asyncService;
@PostMapping("/async")
public String handleRequest() {
asyncService.asynchronousCall();
return "Hello from MyController!";
}
}
@Service
public class AsyncService {
@Async
public void asynchronousCall() {
// Your long-running task goes here
System.out.println("Hello from asynchronousCall!");
}
}

In this example, the handleRequest method in the controller class calls the asynchronousCall method in the AsyncService class asynchronously using the @Async annotation. This allows the request to be handled immediately without blocking for the long-running computation.

Remember to always handle potential exceptions and errors properly when dealing with asynchronous computations!