How Java implements asynchronous programming using JDeferred

JDeferred is a Java asynchronous programming framework that provides a concise way to handle asynchronous tasks and callbacks. It allows developers to write code in a sequential manner without worrying about the details of asynchronous tasks, thus simplifying asynchronous programming. The commonly used key methods are as follows: 1. Promise(): Create a new Promise object that represents the results of an asynchronous task. 2. Resolve(): Pass a value or object as a successful result to Promise. 3. reject(): Pass an error object as the result of a failure to Promise. 4. done(): Add a callback function that will be called when Promise is successful. 5. fail (): Add a callback function that will be called when Promise fails. 6. always(): Add a callback function that is called when Promise succeeds or fails. The following is a Java example code for implementing asynchronous programming using JDeferred: Firstly, add the JDeferred dependency in the pom.xml file: <dependency> <groupId>org.jdeferred</groupId> <artifactId>jdeferred-core</artifactId> <version>1.2.12</version> </dependency> Then, the following example code can be used to demonstrate the usage of JDeferred: import org.jdeferred.Deferred; import org.jdeferred.Promise; import org.jdeferred.impl.DeferredObject; public class JDeferredExample { public static void main(String[] args) { Deferred<String, Integer, Integer> deferred = new DeferredObject<>(); Promise<String, Integer, Integer> promise = deferred.promise(); promise.done(result -> System.out.println("Success: " + result)) .fail(e -> System.out.println("Error: " + e)) .always((state, result, rejection) -> System.out.println("Always executed")); //Simulate asynchronous operations new Thread(() -> { try { Thread.sleep(2000); deferred.resolve("Hello, JDeferred!"); } catch (InterruptedException e) { deferred.reject(500); } }).start(); } } In the above example code, we created a Deferred object that represents the results of an asynchronous task. Then, we created a Promise object using the promise() method to listen on the results. In the done() method, we define a callback function that is called when the asynchronous task is successful. In the fail () method, we define a callback function that is called when an asynchronous task fails. In the always () method, we define a callback function that will be called regardless of whether the asynchronous task succeeds or fails. In the simulated asynchronous operation, we pass the successful result to the Promise object by calling the resolve() method. In practical applications, asynchronous code can be replaced with specific business logic. From the above example code, we can see that the JDeferred framework simplifies the complexity of asynchronous programming, making the processing of asynchronous tasks more intuitive and sequential.