How to simplify the work with databases in Java app?

By using the Java Database Connectivity api you can simplify Java app work with databases greatly
08 August 2017   536


Popular general-purpose programming language and computing platform

Combining database with a Java application can be a complicated task. From one side, Java does not support multi-line string constants, so developers can end up with code that looks like this:

String sql_query = "select *" + "from user_table" + "where name like 'John%

This line of code is not "very pretty" but also has errors. Did you notice the missing space between user_table and where? A further challenge when working with SQL in Java is that we often need to build the SQL dynamically.

Java Database Connectivity (JDBC), is a standard Java API for database-independent connectivity between the Java programming language and a wide range of databases. Using JDBC one can send statements to almost any relational database. Thus, JDBC is a Java API for executing the SQL statements and supports basic SQL functionality.

So, what exactly JDBC do? Here's the list:

  • Making a connection to the database.
  • Creating SQL statements.
  • Executing SQL queries in the database.
  • Viewing and Modifying the resulting records.

Learn more about JDBC. You will be using Eclipse Kepler SR2, JDK 8, MySQL Database and Maven to create JDBC Query Builder.

What is Web3j?

Small review of lightweight Java and Android library for integration with Ethereum clients
15 December 2017   839

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.