How to store lambdas in list in Java 8?

Learn how to create list with lambdas using Java 8 power
31 October 2017   655

You can certainly create a list with lambdas as:

List<BinaryOperator<Integer>> opcodes = Arrays.asList((x, y) -> y, (x, y) -> ++x);

// sample
int a=14,b=16;
System.out.println(opcodes.get(0).apply(a, b)); // prints 16
System.out.println(opcodes.get(1).apply(a, b)); // prints 15

Or redressing the way you were trying to initializing the list

List<BinaryOperator<Integer>> opcodes = new ArrayList<BinaryOperator<Integer>>() {{
    add((x, y) -> y);
    add((x, y) -> ++x);
    add((x, y) -> --x);
    add((x, y) -> x + y);
    add((x, y) -> x - y);

What is Web3j?

Small review of lightweight Java and Android library for integration with Ethereum clients
15 December 2017   816

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.