However, in early 2015, the developers determined that the goals of the project could not be accomplished as part of the GWT project and decided to break it out into its own project. Originally, J2CL was associated with the GWT project. The project was open sourced late last year, but talks of the project go as far back as 2014. The developers claim it is production ready and serves as 'the underlying technology of the most advanced GSuite apps developed by Google including GMail, Inbox, Docs, Slides and Calendar.' const HelloWorld = goog.require('com.acme') The following Java class, ran through J2CL: package com.acmeĬan be used in JavaScript like below. A slightly modified excerpt of that example is included below showing an annotated Java class and how it can be used in JavaScript. The project includes a very simple 'hello world' example to demonstrate usage. By default, translated code is not public and a number of Java annotations from JsInterop can be used to identify what classes, methods, instance variables, or other code should be exposed. J2CL can translate most existing Java code from source but not all Java APIs are supported, such as the Java reflection API. Another use might be reusing a library written in Java in a Node.js application. J2CL does the transpilation of all document manipulation and rendering logic from Java -> JS'. For example, Thomas Deegan, a previous contributor to the J2CL project, says 'the code powering Google Docs front end needs to be written for web. One such way is to ensure complex logic running on multiple platforms implemented in different technologies, can be shared across platforms. The tool was developed with flexibility in mind and can be applied in a number of different ways. According to the developers, 'ou can use J2CL to just make some Java code accessible from JavaScript or go all the way to create a whole application with it whatever best suits your needs.' Instead, J2CL is about interoperability and cross-platform code reuse. J2CL attempts to solve a different problem than similar Java-to-Javascript frameworks such as GWT, and it is not meant to compete with or replace existing JavaScript frameworks. J2CL developers say the compiler 'enables seamless use of Java in your JavaScript applications.' Designed, developed, and open-sourced by Google, J2CL is a source-to-source compiler that converts Java to Javascript.

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