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JVM
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. The JVM reference implementation is developed by the OpenJDK project as open source code and includes a JIT compiler called HotSpot. The commercially supported Java releases available from Oracle are based on the OpenJDK runtime. Eclipse OpenJ9 is another open source JVM for OpenJDK. JVM specification The Java virtual machine is an abstract (virtual) computer defined by a specification. It is a part of the Java runtime environment. The garbage collection algo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Java (software Platform)
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, Sandbox (computer security), sandboxed environments to provide many features of native applications through being embedded in HTML pages. Writing in the Java (programming language), Java programming language is the primary way to produce code that will be deployed as Java byte code, byte code in a Java virtual machine (JVM); byte code compilers are also available for other languages, including Ada (programming language), Ada, JavaScript, Kotlin (programming language), Kotlin (Google's preferred Android language), Python (programming language), Python, and Ruby (p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of JVM Languages
This list of JVM languages comprises notable computer programming languages that are used to produce computer software that runs on the Java virtual machine (JVM). Some of these languages are interpreted by a Java program, and some are compiled to Java bytecode and just-in-time (JIT) compiled during execution as regular Java programs to improve performance. The JVM was initially designed to support only the language Java. However, over time, additional languages were adapted or designed to run on the Java platform. JVM languages High-profile languages As of 2024, according to the TIOBE index of the top 100 programming languages, and PyPL, the top JVM languages are: * Java (#3, at one point at #1; #2 at PyPL), a statically-typed object-oriented language * Kotlin (#21, at one point at #18; #13 at PyPL), a statically-typed language from JetBrains, the developers of IntelliJ IDEA and Google's preferred language for Android * Scala (#26, at one point at #20; #22 at P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OpenJ9
Eclipse OpenJ9 (previously known as IBM J9) is a high performance, scalable, Java virtual machine (JVM) implementation that is fully compliant with the Java Virtual Machine Specification. OpenJ9 can be built from source, or can be used with pre-built binaries available at thIBM Semeru Runtimesproject for a number of platforms including Linux, Windows and macOS. OpenJ9 is also a core component of the IBM developer kit, which is embedded in many IBM middleware products, including WebSphere Application Server and Websphere Liberty. OpenJ9 is also a component of Open Liberty. Extensive configuration options ensure that the JVM can be tuned to satisfy the requirements of a wide range of Java applications, from complex enterprise applications that run on mainframe hardware to short-lived applications that run on container-based cloud services. cloud statement: The design of the J9 VM has been aimed at portability to different platforms, as well as scaling from mobile phones all t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Java Bytecode
Java bytecode is the instruction set of the Java virtual machine (JVM), the language to which Java and other JVM-compatible source code is compiled. Each instruction is represented by a single byte, hence the name bytecode, making it a compact form of data. Due to the nature of bytecode, a Java bytecode program is runnable on any machine with a compatible JVM, without the lengthy process of compiling from source code. Java bytecode is used at runtime either interpreted by a JVM or compiled to machine code via just-in-time (JIT) compilation and run as a native application. As Java bytecode is designed for a cross-platform compatibility and security, a Java bytecode application tends to run consistently across various hardware and software configurations. Relation to Java In general, a Java programmer does not need to understand Java bytecode or even be aware of it. However, as suggested in the IBM developerWorks journal, "Understanding bytecode and what bytecode is li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HotSpot (virtual Machine)
HotSpot, released as Java HotSpot Performance Engine, is a Java virtual machine for desktop and server computers, developed by Sun Microsystems which was purchased by and became a division of Oracle Corporation in 2010. Its features improved performance via methods such as just-in-time compilation and adaptive optimization. It is the de facto Java Virtual Machine, serving as the reference implementation of the Java programming language. History The Java HotSpot Performance Engine was released on April 27, 1999, built on technologies from an implementation of the programming language Smalltalk named Strongtalk, originally developed by Longview Technologies, which traded as Animorphic. The Longview virtual machine was based on the Self virtual machine, with an interpreter replacing the fast-and-dumb first compiler. When Sun cancelled the Self project, two key people, Urs Hölzle and Lars Bak left Sun to start Longview. In 1997, Sun Microsystems purchased Animorphic. Shor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OpenJDK
OpenJDK (Open Java Development Kit) is a free and open-source implementation of the Java Platform, Standard Edition (Java SE). It is the result of an effort Sun Microsystems began in 2006, four years before the company was acquired by Oracle Corporation. The implementation is licensed under the GNU General Public License 2 with a linking exception, preventing components that linked to the Java Class Library becoming subject to the terms of the GPL license. OpenJDK is the official reference implementation of Java SE since version 7, and is the most popular distribution of the JDK. History Sun's promise and initial release Sun announced in JavaOne 2006 that Java would become open-source software, and on October 25, 2006, at the Oracle OpenWorld conference, Jonathan Schwartz said that the company intended to announce the open-sourcing of the core Java Platform within 30 to 60 days. Sun released the Java HotSpot virtual machine and compiler as free software under the GNU Gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concurrent Mark Sweep Collector
The concurrent mark sweep collector (concurrent mark-sweep collector, concurrent collector or CMS) was a mark-and-sweep garbage collector in the Oracle HotSpot Java virtual machine 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 descr ... (JVM) available since version 1.4.1. It was deprecated on version 9 and removed on version 14, so from Java 15 it is no longer available. HotSpot garbage collectors The HotSpot JVM selects the default garbage collector based on several factors. The newer Garbage-First collector (G1) was planned to replace CMS. That change was finally done in version 9. To launch the JVM with this garbage collector you can add this property to the java command line -XX:+UseConcMarkSweepGC when using Java version less than 14. See also * List of Java virtual machin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Class (file Format)
A Java class file is a file (with the filename extension) containing Java bytecode that can be executed on the Java Virtual Machine (JVM). A Java class file is usually produced by a Java compiler from Java programming language source files ( files) containing Java classes (alternatively, other JVM languages can also be used to create class files). If a source file has more than one class, each class is compiled into a separate class file. Thus, it is called a file because it contains the bytecode for a single class. JVMs are available for many platforms, and a class file compiled on one platform will execute on a JVM of another platform. This makes Java applications platform-independent. History On 11 December 2006, the class file format was modified under Java Specification Request (JSR) 202. File layout and structure Sections There are 10 basic sections to the Java class file structure: * Magic Number: 0xCAFEBABE * Version of Class File Format: the minor and maj ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Java Development Kit
The Java Development Kit (JDK) is a distribution of Java technology by Oracle Corporation. It implements the Java Language Specification (JLS) and the Java Virtual Machine Specification (JVMS) and provides the Standard Edition (SE) of the Java Application Programming Interface (API). It is derivative of the community driven OpenJDK which Oracle stewards. It provides software for working with Java applications. Examples of included software are the Java virtual machine, a compiler, performance monitoring tools, a debugger, and other utilities that Oracle considers useful for Java programmers. Oracle releases the current version of the software under the Oracle No-Fee Terms and Conditions (NFTC) license. Oracle releases binaries for the x86-64 architecture for Windows, macOS, and Linux based operating systems, and for the aarch64 architecture for macOS and Linux. Previous versions supported the Oracle Solaris operating system and SPARC architecture. Oracle's primary implementat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Garbage-first Collector
Garbage-First (G1) is a garbage collection algorithm introduced in the Oracle HotSpot Java virtual machine (JVM) 6 Update 14 and supported from 7 Update 4. It was planned to replace concurrent mark sweep collector (CMS) in JVM 7 and was made default in Java 9. Garbage collector Garbage-First (G1) collector is a server-style garbage collector, targeted for multiprocessors with large memories, that meets a soft real-time goal with high probability, while achieving high-throughput. G1 preferentially collects regions with the least amount of live data, or "garbage first". G1 is the long term replacement of CMS. Whole-heap operations, such as global marking, are performed concurrently with the application threads, to prevent interruptions proportional to heap or live-data size. Concurrent marking provides both collection completeness and identifies regions ripe for reclamation via compacting evacuation. This evacuation is performed in parallel on multiprocessors, to decrease pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Java Platform, Standard Edition
Java Platform, Standard Edition (Java SE) is a computing platform for development and deployment of porting, portable code for desktop computer, desktop and server (computing), server environments. Java SE was formerly known as Java 2 Platform, Standard Edition (J2SE). The platform uses the Java (programming language), Java programming language and is part of the Java (software platform), Java software-platform family. Java SE defines a range of general-purpose APIs—such as List of Java APIs, Java APIs for the Java Class Library—and also includes the Java Language Specification and the Java Virtual Machine Specification. OpenJDK is the official reference implementation since version 7. Nomenclature, standards and specifications The platform was known as ''Java 2 Platform, Standard Edition'' or ''J2SE'' from version 1.2, until the name was changed to ''Java Platform, Standard Edition'' or ''Java SE'' in version 1.5. The "SE" is used to distinguish the base platform from th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
JIT Compiler
In computing, just-in-time (JIT) compilation (also dynamic translation or run-time compilations) is compiler, compilation (of Source code, computer code) during execution of a program (at run time (program lifecycle phase), run time) rather than before execution. This may consist of source code translation but is more commonly bytecode translation to machine code, which is then executed directly. A system implementing a JIT compiler typically continuously analyses the code being executed and identifies parts of the code where the speedup gained from compilation or recompilation would outweigh the overhead of compiling that code. JIT compilation is a combination of the two traditional approaches to translation to machine code—Ahead-of-time compilation, ahead-of-time compilation (AOT), and Interpreter (computing), interpretation—and combines some advantages and drawbacks of both. Roughly, JIT compilation combines the speed of compiled code with the flexibility of interpre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
