Java is a high-level, class-based, object-oriented programming language that is designed to have as few implementation dependencies as possible. It is a general-purpose programming language intended to let programmers write once, run anywhere (WORA), meaning that compiled Java code can run on all platforms that support Java without the need to recompile. Java applications are typically compiled to bytecode that can run on any Java virtual machine (JVM) regardless of the underlying computer architecture. The syntax of Java is similar to C and C++, but has fewer low-level facilities than either of them. The Java runtime provides dynamic capabilities that are typically not available in traditional compiled languages.
A Java virtual machine (JVM) is a virtual machine that enables a computer to run Java programs as well as programs written in other languages that are also compiled to Java bytecode. The JVM is detailed by a specification that formally describes what is required in a JVM implementation. Having a specification ensures interoperability of Java programs across different implementations so that program authors using the Java Development Kit (JDK) need not worry about idiosyncrasies of the underlying hardware platform.
Jakarta EE, formerly Java Platform, Enterprise Edition and Java 2 Platform, Enterprise Edition (J2EE), is a set of specifications, extending Java SE with specifications for enterprise features such as distributed computing and web services. Jakarta EE applications are run on reference runtimes, which can be microservices or application servers, which handle transactions, security, scalability, concurrency and management of the components they are deploying.
The Jakarta Project created and maintained open source software for the Java platform. It operated as an umbrella project under the auspices of the Apache Software Foundation, and all Jakarta products are released under the Apache License. As of December 21, 2011 the Jakarta project was retired because no subprojects were remaining.
The GNU Compiler for Java (GCJ) is a discontinued free compiler for the Java programming language. It was part of the GNU Compiler Collection.
AspectJ is an aspect-oriented programming (AOP) extension for the Java programming language, created at PARC. It is available in Eclipse Foundation open-source projects, both stand-alone and integrated into Eclipse. AspectJ has become a widely used de facto standard for AOP by emphasizing simplicity and usability for end users. It uses Java-like syntax, and included IDE integrations for displaying crosscutting structure since its initial public release in 2001.
WebObjects is a discontinued Java web application server and a server-based web application framework originally developed by NeXT Software, Inc.
GNU Classpath is a free software implementation of the standard class library for the Java programming language. Most classes from J2SE 1.4 and 5.0 are implemented. Classpath can thus be used to run Java-based applications. GNU Classpath is a part of the GNU Project. It was originally developed in parallel with libgcj due to license incompatibilities, but later the two projects merged.
Apache Harmony is a retired open source, free Java implementation, developed by the Apache Software Foundation. It was announced in early May 2005 and on October 25, 2006, the board of directors voted to make Apache Harmony a top-level project. The Harmony project achieved 99% completeness for J2SE 5.0, and 97% for Java SE 6. The Android operating system has historically been a major user of Harmony, although since Android Nougat it increasingly relies on OpenJDK libraries.
Apache Tapestry is an open-source component-oriented Java web application framework conceptually similar to JavaServer Faces and Apache Wicket. Tapestry was created by Howard Lewis Ship, and was adopted by the Apache Software Foundation as a top-level project in 2006.
Java is a set of computer software and specifications that provides a software platform for developing application software and deploying it in a cross-platform computing environment. Java is used in a wide variety of computing platforms from embedded devices and mobile phones to enterprise servers and supercomputers. Java applets, which are less common than standalone Java applications, were commonly run in secure, sandboxed environments to provide many features of native applications through being embedded in HTML pages.
Google Web Toolkit, or GWT Web Toolkit, is an open-source set of tools that allows web developers to create and maintain JavaScript front-end applications in Java. It is licensed under Apache License 2.0.
The Spring Framework is an application framework and inversion of control container for the Java platform. The framework's core features can be used by any Java application, but there are extensions for building web applications on top of the Java EE platform. The framework does not impose any specific programming model.. The framework has become popular in the Java community as an addition to the Enterprise JavaBeans (EJB) model. The Spring Framework is free and open source software.
The ASM library is a project of the OW2 consortium. It provides a simple API for decomposing, modifying, and recomposing binary Java classes. The project was originally conceived and developed by Eric Bruneton. ASM is Java-centric at present, and does not currently have a backend that exposes other bytecode implementations.
The Java Class Loader, part of the Java Runtime Environment, dynamically loads Java classes into the Java Virtual Machine. Usually classes are only loaded on demand. The virtual machine will only load the class files required for executing the program. The Java run time system does not need to know about files and file systems as this is delegated to the class loader.
The Jakarta Expression Language is a special purpose programming language mostly used in Jakarta EE web applications for embedding and evaluating expressions in web pages. The specification writers and expert groups of the Java EE web-tier technologies have worked on a unified expression language which was first included in the JSP 2.1 specification (JSR-245), and later specified by itself in JSR-341, part of Java EE 7.
Eclipse OpenJ9 is a high performance, scalable, Java virtual machine (JVM) implementation that is fully compliant with the Java Virtual Machine Specification.
This article compares the application programming interfaces (APIs) and virtual machines (VMs) of the programming language Java and operating system Android.
Java code coverage tools are of two types: first, tools that add statements to the Java source code and require its recompilation. Second, tools that instrument the bytecode, either before or during execution. The goal is to find out which parts of the code are tested by registering the lines of code executed when running a test.
