JShell

Last updated

JShell is a Java read-eval-print loop which was first introduced in the JDK 9. [1] It is tracked by JEP 222 jshell: The Java Shell (Read-Eval-Print Loop). [2] One reason why JShell was proposed for Java 9 is the lack of a standard interactive environment for the language; the de facto library to use a Java REPL was often BeanShell, which has been dormant since 2003, and arbitrarily diverged from the Java language. [3] [4]

Contents

Example

jshell> int a[] = { 0, 1, 3, 5, 8 } a ==> int[5] { 0, 1, 3, 5, 8 }  jshell> int fact(int n) {    ...>     return n < 2 ? 1 : n * fact(n - 1);    ...> } |  created method fact(int)  jshell> for (int i = 0; i < a.length; ++i)    ...>     a[i] = fact(a[i]);  jshell> a a ==> int[5] { 1, 1, 6, 120, 40320 }

See also

Related Research Articles

<span class="mw-page-title-main">Java virtual machine</span> Virtual machine that runs Java programs

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.

Java Platform, Standard Edition is a computing platform for development and deployment of portable code for desktop and server environments. Java SE was formerly known as Java 2 Platform, Standard Edition (J2SE).

Jakarta XML Binding is a software framework that allows Java EE developers to map Java classes to XML representations. JAXB provides two main features: the ability to marshal Java objects into XML and the inverse, i.e. to unmarshal XML back into Java objects. In other words, JAXB allows storing and retrieving data in memory in any XML format, without the need to implement a specific set of XML loading and saving routines for the program's class structure. It is similar to xsd.exe and XmlSerializer in the .NET Framework.

java.nio is a collection of Java programming language APIs that offer features for intensive I/O operations. It was introduced with the J2SE 1.4 release of Java by Sun Microsystems to complement an existing standard I/O. NIO was developed under the Java Community Process as JSR 51. An extension to NIO that offers a new file system API, called NIO.2, was released with Java SE 7 ("Dolphin").

Javadoc is a documentation generator created by Sun Microsystems for the Java language for generating API documentation in HTML format from Java source code. The HTML format is used for adding the convenience of being able to hyperlink related documents together.

BeanShell is a small, free, embeddable Java source interpreter with object scripting language features, written in Java. It runs in the Java Runtime Environment (JRE), dynamically executes standard Java syntax and extends it with common scripting conveniences such as loose types, commands, and method closures, like those in Perl and JavaScript.

A Java compiler is a compiler for the Java programming language.

A read–eval–print loop (REPL), also termed an interactive toplevel or language shell, is a simple interactive computer programming environment that takes single user inputs, executes them, and returns the result to the user; a program written in a REPL environment is executed piecewise. The term usually refers to programming interfaces similar to the classic Lisp machine interactive environment. Common examples include command-line shells and similar environments for programming languages, and the technique is very characteristic of scripting languages.

<span class="mw-page-title-main">GlassFish</span> Application server project

GlassFish is an open-source Jakarta EE platform application server project started by Sun Microsystems, then sponsored by Oracle Corporation, and now living at the Eclipse Foundation and supported by Payara, Oracle and Red Hat. The supported version under Oracle was called Oracle GlassFish Server. GlassFish is free software and was initially dual-licensed under two free software licences: the Common Development and Distribution License (CDDL) and the GNU General Public License (GPL) with the Classpath exception. After having been transferred to Eclipse, GlassFish remained dual-licensed, but the CDDL license was replaced by the Eclipse Public License (EPL).

In the Java computer programming language, an annotation is a form of syntactic metadata that can be added to Java source code. Classes, methods, variables, parameters and Java packages may be annotated. Like Javadoc tags, Java annotations can be read from source files. Unlike Javadoc tags, Java annotations can also be embedded in and read from Java class files generated by the Java compiler. This allows annotations to be retained by the Java virtual machine at run-time and read via reflection. It is possible to create meta-annotations out of the existing ones in Java.

<span class="mw-page-title-main">Java (software platform)</span> Set of computer software and specifications

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.

The Java language has undergone several changes since JDK 1.0 as well as numerous additions of classes and packages to the standard library. Since J2SE 1.4, the evolution of the Java language has been governed by the Java Community Process (JCP), which uses Java Specification Requests (JSRs) to propose and specify additions and changes to the Java platform. The language is specified by the Java Language Specification (JLS); changes to the JLS are managed under JSR 901. In September 2017, Mark Reinhold, chief Architect of the Java Platform, proposed to change the release train to "one feature release every six months" rather than the then-current two-year schedule. This proposal took effect for all following versions, and is still the current release schedule.

<span class="mw-page-title-main">JavaFX</span> Java software platform for GUI

JavaFX is a software platform for creating and delivering desktop applications, as well as rich web applications that can run across a wide variety of devices. JavaFX has support for desktop computers and web browsers on Microsoft Windows, Linux, and macOS, as well as mobile devices running iOS and Android, through Gluon Mobile.

The Java Class Library (JCL) is a set of dynamically loadable libraries that Java Virtual Machine (JVM) languages can call at run time. Because the Java Platform is not dependent on a specific operating system, applications cannot rely on any of the platform-native libraries. Instead, the Java Platform provides a comprehensive set of standard class libraries, containing the functions common to modern operating systems.

The Java Platform Module System specifies a distribution format for collections of Java code and associated resources. It also specifies a repository for storing these collections, or modules, and identifies how they can be discovered, loaded and checked for integrity. It includes features such as namespaces with the aim of fixing some of the shortcomings in the existing JAR format, especially the JAR Hell, which can lead to issues such as classpath and class loading problems.

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.

Java Database Connectivity (JDBC) is an application programming interface (API) for the Java programming language which defines how a client may access a database. It is a Java-based data access technology used for Java database connectivity. It is part of the Java Standard Edition platform, from Oracle Corporation. It provides methods to query and update data in a database, and is oriented toward relational databases. A JDBC-to-ODBC bridge enables connections to any ODBC-accessible data source in the Java virtual machine (JVM) host environment.

Nashorn is a JavaScript engine developed in the Java programming language originally by Oracle and later by the OpenJDK Community. It relies on the support for dynamically typed languages on the Java Platform Nashorn has been included with Java 8 through JDK 14.

The JDK Enhancement Proposal is a process drafted by Oracle Corporation for collecting proposals for enhancements to the Java Development Kit and OpenJDK.

<span class="mw-page-title-main">GraalVM</span> Virtual machine software

GraalVM is a Java Development Kit (JDK), written in Java. The open-source distribution of GraalVM is based on OpenJDK, and the enterprise distribution is based on Oracle JDK. As well as just-in-time (JIT) compilation, GraalVM can compile a Java application ahead-of-time so that it starts instantly, provides peak performance with no warmup, and uses fewer resources. It provides additional programming languages and execution modes. The first production-ready release, GraalVM 19.0, was distributed in May 2019. The most recent release is GraalVM for JDK 21, made available in September 2023.

References

  1. ↑ "Oracle Announces Java SE 9 and Java EE 8". Oracle Corporation. 2017-09-21. Retrieved 2017-09-25.
  2. ↑ "JEP 222: jshell: The Java Shell (Read-Eval-Print Loop)". Oracle Corporation. 2016-10-10. Retrieved 2016-11-01. Provide an interactive tool to evaluate declarations, statements, and expressions of the Java programming language, together with an API so that other applications can leverage this functionality
  3. ↑ "JEP 222: jshell: The Java Shell (Read-Eval-Print Loop)". Oracle Corporation. 2016-10-10. Retrieved 2016-11-01. Another alternative is to maintain the status quo: Use another language or use a third-party REPL such as BeanShell, though that particular REPL has been dormant for many years, is based on JDK 1.3, and makes arbitrary changes to the language.
  4. ↑ "JShell, the Java 9 REPL – What does it do?". jaxenter.com. 2015-09-03. Retrieved 2016-11-01. BeanShell (just like Groovy, too by the way) made an attempt of standardisation by the Java Community Process in JSR 274 – a JSR that did not produce any notable output, in spite of the fact that (or perhaps because?) two major companies, Sun and Google, had joined the expert group. Under the JCP.next initiative this JSR was declared "Dormant".
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.