Java

Java
Name	Java
Paradigm	Object-oriented, structured, imperative, generic, reflective, concurrent
Designer	James Gosling
Developer	Sun Microsystems (now owned by Oracle Corporation)
Latest release version	Java 21
Latest release date	September 2023
Typing	Static, strong, safe, nominative, manifest
Influenced by	C, C++, Objective-C, Smalltalk, Eiffel
Influenced	C#, Kotlin, Scala, Groovy
Operating system	Microsoft Windows, macOS, Linux, Solaris
License	GPL (OpenJDK), proprietary (Oracle JDK)

Java is a high-level, class-based, object-oriented programming language designed to have as few implementation dependencies as possible. It is a general-purpose language intended to let application developers "write once, run anywhere" (WORA), meaning that compiled Java bytecode can run on all platforms that support Java without the need for recompilation. Originally developed by James Gosling at Sun Microsystems and released in 1995, it has since become one of the most widely used programming languages, particularly for client-server web applications and large-scale enterprise systems.

History

The language was conceived in 1991 by James Gosling, Mike Sheridan, and Patrick Naughton as part of the Green Project at Sun Microsystems. Its initial goal was to develop a language for digital devices such as set-top boxes, but it found its major niche with the rise of the World Wide Web. The language was initially called Oak after an oak tree outside Gosling's office, but was renamed Java in 1995. A pivotal moment in its history was the release of Netscape Navigator with support for Java applets, which propelled its adoption for interactive web content. Key figures in its early development included Bill Joy and Guy L. Steele Jr.. In 2009-2010, Oracle Corporation acquired Sun Microsystems, becoming the language's steward. Major releases have been governed by the Java Community Process (JCP), with significant versions including J2EE, Java SE 8, and the modern six-month release cadence initiated with Java 10.

Features

Java is known for its key design principles of simplicity, portability, and security. A core feature is its use of the Java Virtual Machine (JVM), which executes bytecode and provides platform independence through the Write once, run anywhere principle. The language employs automatic garbage collection for memory management, reducing the burden on developers. It features a robust exception handling mechanism and strong support for multithreading and concurrent computing. The language's security model, including the sandbox for applets and the Java Cryptography Architecture, was historically significant. Other important characteristics include its object-oriented programming nature, static typing, and extensive standard library known as the Java Class Library.

Syntax

The syntax of Java is largely influenced by C and C++, but with a simpler object model and fewer low-level facilities. A fundamental unit is the class, and every application must contain a `main` method. It uses curly braces `{}` to define blocks of code and semicolons to terminate statements. Primitive data types like `int`, `double`, and `boolean` are distinct from object types. Control flow statements, such as `if`, `for`, `while`, and `switch`, are similar to those in C. A distinctive feature is its single inheritance model for classes, but it supports multiple inheritance of types through interfaces. Annotations, introduced in Java 5, provide metadata about the code. The syntax for generics, added in J2SE 5.0, uses angle brackets (e.g., `List`).

Development tools

The primary tool for Java development is the Java Development Kit (JDK), which includes the compiler (`javac`), the Java Virtual Machine (`java`), and other utilities like `jar` and `javadoc`. The most popular Integrated Development Environment (IDE) is Eclipse, followed by IntelliJ IDEA from JetBrains and NetBeans. Build automation tools are essential, with Apache Maven and Gradle being the most widely used. For dependency management, repositories like Maven Central are standard. Other critical tools include the Apache Ant build tool, JUnit for unit testing, and Log4j for logging. Profiling and monitoring tools, such as VisualVM and Java Mission Control, are part of the ecosystem. The OpenJDK project is the primary open-source implementation.

Applications

Java is used in a vast array of application domains. It is a cornerstone of large-scale enterprise software, powering backend systems for major corporations and banks, often using frameworks like Spring Framework and platforms like Jakarta EE. It is historically famous for Java applets in web browsers, though this use has declined. On the server side, it is ubiquitous in web applications, with technologies like JavaServer Pages (JSP) and Apache Tomcat. The Android mobile operating system uses Java as a primary language for application development, via the Android SDK. It is also prevalent in big data technologies like Apache Hadoop and Apache Spark, and in scientific computing. Embedded systems, financial trading platforms, and games like Minecraft are other notable applications.

Platforms

The Java platform is organized into several distinct editions targeting different environments. The Java Platform, Standard Edition (Java SE) provides the core functionality and is the basis for all other editions. The Java Platform, Enterprise Edition (Java EE), now known as Jakarta EE after its transfer to the Eclipse Foundation, extends Java SE with specifications for large-scale, distributed enterprise applications. The Java Platform, Micro Edition (Java ME) is a subset for mobile and embedded devices. The execution environment is centered on the Java Virtual Machine (JVM), with popular implementations including the HotSpot JVM from Oracle Corporation and OpenJ9 from the Eclipse Foundation. The platform's "write once, run anywhere" capability is enabled by these standardized runtime environments across operating systems like Microsoft Windows, Linux, and macOS.

Category:Programming languages Category:Object-oriented programming languages Category:Java (programming language)