Application cases of functional framework in the Java library

Application cases of functional programming in modern Java libraries The application of functional programming in the Java library is increasingly welcomed by developers.By using the characteristics of functional programming paradigms, it can be more concise, maintained and tested.This article will introduce some application cases that use functional programming in the Java library, and include the corresponding Java code example. 1. Fire Stream （流 API） Stream API is a functional programming style flow processing tool introduced by Java 8, which provides a more concise and expressive way to process collection data.The following is an example: List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5); // Use stream to filter out the even number and seek peace int sum = numbers.stream() .filter(n -> n % 2 == 0) .mapToInt(Integer::intValue) .sum(); System.out.println("Sum of even numbers: " + sum); // 输出：Sum of even numbers: 6 By using the Stream API, we can chain the process of setting data processing, which is very intuitive.The data can be filtered by the `Filter` method, the data is converted through the` Maptoint` method, and then the operation of the operation is to find the sum of the even. 2. CompletableFuture (asynchronous programming) CompletableFuture is a class introduced in Java 8 for asynchronous programming.It allows developers to combine and assemble asynchronous tasks and process the results through functional callbacks.The following is an example: // asynchronous execution task CompletableFuture<String> future1 = CompletableFuture.supplyAsync(() -> { // Simulation time -consuming operation try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } return "Hello"; }); // asynchronous execution task CompletableFuture<String> future2 = CompletableFuture.supplyAsync(() -> "World"); // The results of the two tasks of the combination CompletableFuture<String> combinedFuture = future1.thenCombine(future2, (s1, s2) -> s1 + " " + s2); // Waiting for the task to complete and print the results CombineDFUTURE.THENACCEPT (System.out :: Println); // Output: Hello Worldd By using CompletableFuture, we can perform asynchronous programming in a more concise way.You can create an asynchronous execution task through the `SUPPLYASYNC` method, and use the method of combining the method of the` Theencombine` method.Finally, the results after the combination are processed through the `TheenacCEPT` method. 3. Function interface (function interface) Java 8 introduces a set of functional interfaces, the most commonly used is the `Function` interface.Function interface represents a mapping relationship between input and output.The following is an example: List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5); // Use funion for numerical calculation List<Integer> doubledNumbers = numbers.stream() .map(n -> n * 2) .collect(Collectors.toList()); System.out.println("Doubled numbers: " + doubledNumbers); // 输出：Doubled numbers: [2, 4, 6, 8, 10] By using the `Map` method of the Function interface, we can change each element in the set.In the above example, we doubled each value. in conclusion The application cases of functional programming in the Java library are very rich.By using STREAM API, CompletableFuture, and functional interface functions, you can write more concise, maintenance and test -available code.Developers can flexibly use functional programming in the Java library according to specific needs to improve development efficiency and code quality.