CheerpJ converts Java apps into JavaScript for the web

Convertation of applications and Java libraries  to web applications is no longer challenge. CheerpJ has managed to develop an unique technology
26 June 2017   729

Java is a popular general-purpose programming language and computing platform

CheerpJ is the Java compiler for Web applications which serves to convert any Java application and library to a browser-based Web application effortlessly.

The CheerpJ Applet Viewer extension, created by Leaning Technologies and based on the CheerpJ technology, takes Java bytecode and turns it into JavaScript without needing the Java source or any plugin. Converted applications that can be deployed on a web server via both jar.js JavaScript and .jar files.


JavaScript is a lightweight interpreted or JIT-compiled programming language with first-class functions

Bidirectional liaison between Java and JavaScript is quite challenging for any JavaScript library and browser API from Java as well.

The most important features of Cheerp®J are following:

  • open-source compiler based on LLVM
  • native JavaScript memory model
  • clean access to HTML5 DOM
  • optimized performances and output size
  • JavaScript  interoperability

CheerpJ can generate Java archive (.jar) files as well as one single files including both reflection and dynamic classes.

The Applet Viewer extension compiles the Java applet on the fly, without relying on any remote server. The extension will be available on different popular browsers such as GWT(Google Web Toolkit) and Chrome that are running in a beta release now.

Compared with other technologies, Learning Technologies has no partial implementation of the Java runtime library, they rather convert than adapt to new applications. Technologies, which compile to JavaScript from other languages, include Scala.js, the Kotlin language, and Microsoft’s TypeScript.

Using The CheerpJ Applet Viewer requires no effort and installation of the extension proceeds just one click, creating the icon in the upper right corner of Chrome.
A restricted public release of CheerpJ is expected to be released in the upcoming July. As for a commercial version, it will roll out in the autumn.

What is Web3j?

Small review of lightweight Java and Android library for integration with Ethereum clients
15 December 2017   827

What is webj3?

web3j is a lightweight, highly modular, reactive, type safe Java and Android library for working with Smart Contracts and integrating with clients (nodes) on the Ethereum network:

web3j architecture
Web3j Architecture

This allows you to work with the Ethereum blockchain, without the additional overhead of having to write your own integration code for the platform.

According to the developers, these are the features:

  • Complete implementation of Ethereum's JSON-RPC client API over HTTP and IPC
  • Ethereum wallet support
  • Auto-generation of Java smart contract wrappers to create, deploy, transact with and call smart contracts from native Java code (Solidity and Truffle definition formats supported)
  • Reactive-functional API for working with filters
  • Ethereum Name Service (ENS) support
  • Support for Parity's Personal, and Geth's Personal client APIs
  • Support for Infura, so you don't have to run an Ethereum client yourself
  • Comprehensive integration tests demonstrating a number of the above scenarios
  • Command line tools
  • Android compatible
  • Support for JP Morgan's Quorum via web3j-quorum

It has five runtime dependencies:

  • RxJava for its reactive-functional API
  • OKHttp for HTTP connections
  • Jackson Core for fast JSON serialisation/deserialisation
  • Bouncy Castle (Spongy Castle on Android) for crypto
  • Jnr-unixsocket for *nix IPC (not available on Android)

It also uses JavaPoet for generating smart contract wrappers.

Lear more at GitHub.