国产av日韩一区二区三区精品,成人性爱视频在线观看,国产,欧美,日韩,一区,www.成色av久久成人,2222eeee成人天堂

Home Java javaTutorial lambda expression in Java

lambda expression in Java

Jun 09, 2023 am 10:17 AM
java expression lambda

Lambda expressions in Java

With the release of Java 8, lambda expressions have become one of the most concerned and discussed topics among Java developers. Lambda expressions can simplify Java programmers' tedious writing methods, while also improving program readability and maintainability. In this article, we will take a deep dive into lambda expressions in Java and how they provide a simpler and more intuitive programming experience in Java code.

What is a Lambda expression?

Lambda expression is an anonymous function that can be passed as a parameter to a method or returned from a method. Lambda expressions in Java were mainly introduced to implement functional programming to simplify the writing of anonymous inner classes. In Java, the writing of anonymous inner classes is verbose and unintuitive in some cases. The introduction of lambda expressions makes the writing of code simpler and easier to read.

The syntax of Lambda expression

The lambda expression in Java mainly consists of arrow symbols, parameter list and function body. The following is the basic syntax of lambda expression:

(parameter1, parameter2, ..., parameterN) -> {function body}

The above syntax is explained as follows:

  • parameter1, parameter2, ..., parameterN: Represents the parameters of lambda expression.
  • ->: Arrow symbol, use arrow symbol to separate parameter list and method body.
  • {function body}: Represents the method body of the lambda expression.

The sample code is as follows:

// Lambda expression example
public class LambdaExample {

public static void main(String[] args) {
    // 傳遞 lambda 表達(dá)式給 Thread 類
    Thread t1 = new Thread(() -> System.out.println("Lambda 表達(dá)式"));
    t1.start();
}

}

In the above code, lambda expression() -> System.out.println("Lambda expression") is an anonymous function that will be passed as a parameter to the Thread class in Java.

Type inference for Lambda expressions

In some cases, the Java compiler can automatically infer the type of a lambda expression through the context. For example, when you pass a lambda expression as a parameter to a functional interface, the compiler automatically infers the type of the lambda expression. The sample code is as follows:

// Lambda expression type inference example
public class LambdaTypeInferenceExample {

public static void main(String[] args) {
    // 在 lambda 表達(dá)式作為參數(shù)時(shí)可以自動(dòng)推斷類型
    List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
    numbers.forEach((Integer value) -> System.out.println(value));
}

}

In the above code, Lambda expression (Integer value) -> The type of System.out.println(value) can be automatically inferred without explicitly specifying the type.

Variable scope of Lambda expressions

Unlike anonymous inner classes, lambda expressions can access local variables of the method in which they are located. These local variables are called the "free variables" of the lambda expression. In a lambda expression, free variables can be accessed, but the free variables must be implicitly final or de facto final. The following is a sample code:

// Free variable example of Lambda expression
public class LambdaFreeVariableExample {

public static void main(String[] args) {
    String message = "Hello";
    Runnable runnable = () -> {
        System.out.println(message);
    };
    runnable.run();
}

}

In the above code, the lambda expression () -> System.out.println(message) accesses the free variable message because the message variable is implicitly final.

Lambda Expressions and Stream API

Java 8 also introduces a new Stream API that is closely related to lambda expressions. The Stream API provides a way to operate collections, allowing developers to process collection data more conveniently. Many methods in the Stream API accept lambda expressions as parameters. The following is a sample code:

// Stream API Example
public class StreamExample {

public static void main(String[] args) {
    List<String> list = Arrays.asList("Java", "Spring", "Hibernate", "Struts");
    long count = list.stream()
                    .filter(s -> s.startsWith("S"))
                    .count();
    System.out.println(count);
}

}

In the above code, lambda expressions -> s.startsWith("S") is passed to the Stream API as a parameter of the filter method filter(), which is used to filter strings starting with S.

Summary

The lambda expression in Java is a very important feature, which provides Java programmers with a concise, efficient, easy-to-read, and easy-to-maintain coding method. Not only that, lambda expressions are also closely related to other new features such as Stream API, providing a more convenient and efficient way for Java development. If you are a Java developer, you must actively master and use lambda expressions, which will bring great help to your development work.

The above is the detailed content of lambda expression in Java. For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undress AI Tool

Undress AI Tool

Undress images for free

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Applying Semantic Structure with article, section, and aside in HTML Applying Semantic Structure with article, section, and aside in HTML Jul 05, 2025 am 02:03 AM

The rational use of semantic tags in HTML can improve page structure clarity, accessibility and SEO effects. 1. Used for independent content blocks, such as blog posts or comments, it must be self-contained; 2. Used for classification related content, usually including titles, and is suitable for different modules of the page; 3. Used for auxiliary information related to the main content but not core, such as sidebar recommendations or author profiles. In actual development, labels should be combined and other, avoid excessive nesting, keep the structure simple, and verify the rationality of the structure through developer tools.

Differences Between Callable and Runnable in Java Differences Between Callable and Runnable in Java Jul 04, 2025 am 02:50 AM

There are three main differences between Callable and Runnable in Java. First, the callable method can return the result, suitable for tasks that need to return values, such as Callable; while the run() method of Runnable has no return value, suitable for tasks that do not need to return, such as logging. Second, Callable allows to throw checked exceptions to facilitate error transmission; while Runnable must handle exceptions internally. Third, Runnable can be directly passed to Thread or ExecutorService, while Callable can only be submitted to ExecutorService and returns the Future object to

The requested operation requires elevation Windows The requested operation requires elevation Windows Jul 04, 2025 am 02:58 AM

When you encounter the prompt "This operation requires escalation of permissions", it means that you need administrator permissions to continue. Solutions include: 1. Right-click the "Run as Administrator" program or set the shortcut to always run as an administrator; 2. Check whether the current account is an administrator account, if not, switch or request administrator assistance; 3. Use administrator permissions to open a command prompt or PowerShell to execute relevant commands; 4. Bypass the restrictions by obtaining file ownership or modifying the registry when necessary, but such operations need to be cautious and fully understand the risks. Confirm permission identity and try the above methods usually solve the problem.

How Java ClassLoaders Work Internally How Java ClassLoaders Work Internally Jul 06, 2025 am 02:53 AM

Java's class loading mechanism is implemented through ClassLoader, and its core workflow is divided into three stages: loading, linking and initialization. During the loading phase, ClassLoader dynamically reads the bytecode of the class and creates Class objects; links include verifying the correctness of the class, allocating memory to static variables, and parsing symbol references; initialization performs static code blocks and static variable assignments. Class loading adopts the parent delegation model, and prioritizes the parent class loader to find classes, and try Bootstrap, Extension, and ApplicationClassLoader in turn to ensure that the core class library is safe and avoids duplicate loading. Developers can customize ClassLoader, such as URLClassL

Exploring Different Synchronization Mechanisms in Java Exploring Different Synchronization Mechanisms in Java Jul 04, 2025 am 02:53 AM

Javaprovidesmultiplesynchronizationtoolsforthreadsafety.1.synchronizedblocksensuremutualexclusionbylockingmethodsorspecificcodesections.2.ReentrantLockoffersadvancedcontrol,includingtryLockandfairnesspolicies.3.Conditionvariablesallowthreadstowaitfor

Handling Common Java Exceptions Effectively Handling Common Java Exceptions Effectively Jul 05, 2025 am 02:35 AM

The key to Java exception handling is to distinguish between checked and unchecked exceptions and use try-catch, finally and logging reasonably. 1. Checked exceptions such as IOException need to be forced to handle, which is suitable for expected external problems; 2. Unchecked exceptions such as NullPointerException are usually caused by program logic errors and are runtime errors; 3. When catching exceptions, they should be specific and clear to avoid general capture of Exception; 4. It is recommended to use try-with-resources to automatically close resources to reduce manual cleaning of code; 5. In exception handling, detailed information should be recorded in combination with log frameworks to facilitate later

What is the purpose of the `static` keyword in Java? What is the purpose of the `static` keyword in Java? Jul 05, 2025 am 02:36 AM

Static keywords are used in Java to create variables and methods that belong to the class itself, rather than instances of the class. 1. Static variables are shared by instances of all classes and are suitable for storing data shared by all objects, such as schoolName in the Student class. 2. Static methods belong to classes and do not depend on objects. They are often used in tool functions, such as Math.sqrt(), and can only access other static members. 3. Static code blocks are used to perform initialization operations when class loading, such as loading libraries or setting logs. 4. Static inner classes can be instantiated independently of the external class, but non-static members of the external class cannot be accessed. Rational use of static can effectively manage class-level resources and behaviors.

Explained: Java Polymorphism in Object-Oriented Programming Explained: Java Polymorphism in Object-Oriented Programming Jul 05, 2025 am 02:52 AM

Polymorphism is one of the core features of Java object-oriented programming. Its core lies in "one interface, multiple implementations". It implements a unified interface to handle the behavior of different objects through inheritance, method rewriting and upward transformation. 1. Polymorphism allows the parent class to refer to subclass objects, and the corresponding methods are called according to the actual object during runtime; 2. The implementation needs to meet the three conditions of inheritance relationship, method rewriting and upward transformation; 3. It is often used to uniformly handle different subclass objects, collection storage and framework design; 4. When used, only the methods defined by the parent class can be called. New methods added to subclasses need to be transformed downward and accessed, and pay attention to type safety.

See all articles