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neow3j Documentation and Tutorials

License: Apache License 2.0

neow3j-docs's Introduction

neow3j: A Java/Kotlin/Android Development Toolkit for the Neo Blockchain

Neow3j is a development toolkit that provides easy and reliable tools to build Neo dApps and Smart Contracts using the Java platform (Java, Kotlin, Android). It is an open-source project developed by the community and maintained by AxLabs.

Visit neow3j.io for more information and technical documentation.

If you are in need of a testnet or mainnet Neo node for your dApp but don't want to spend hours on setup, check out 1ClickNode.

Quickstart

Neow3j is composed of an SDK for dApp development and a devpack for smart contract development -- which also includes a compiler (JVM to NeoVM). The following sections describe how to get started with them! 🚀

SDK

To make use of all neow3j SDK features, add io.neow3j:contract to your dependencies.

Gradle

implementation 'io.neow3j:contract:3.22.1'

Maven

<dependency>
    <groupId>io.neow3j</groupId>
    <artifactId>contract</artifactId>
    <version>3.22.1</version>
</dependency>

Releases are available for Neo Legacy and Neo N3. The example above shows the newest release of neow3j for Neo N3. To use the latest release for Neo Legacy, use the version 2.4.0.

Devpack/Compiler

For smart contract development, you need the io.neow3j:devpack dependency. It provides all Neo-related utilities to write your first smart contract on the Neo blockchain!

Then, add the following dependency to your project.

Gradle

implementation 'io.neow3j:devpack:3.22.1'

Maven

<dependency>
    <groupId>io.neow3j</groupId>
    <artifactId>devpack</artifactId>
    <version>3.22.1</version>
</dependency>

Note: The devpack and compiler are only available for Neo N3. Thus, Java cannot be used to compile smart contracts that are compatible with Neo Legacy.

Who's using neow3j? 🚀

Binance
OKEx
AxLabs
GrantShares
Flamingo (FUSD)
NeoCompounder (cNEO)
Neo Blockchain Toolkit
NekoHit
NeoCandy
Neo Playground
Elements
intellij-neo
Would like to be listed here? Contact us or open an issue.

Donate 💰

Help the development of neow3j by sponsoring us using the following addresses:

Crypto	Address
Neo N3	`NfhQyNmMCLCKaaazL6gbvYxtkZNGVb8kRn`
Neo Legacy	`AHb3PPUY6a36Gd6JXCkn8j8LKtbEUr3UfZ`
ETH	`0xe85EbabD96943655e2DcaC44d3F21DC75F403B2f`
BTC	`3L4br7KQ8DCJEZ77nBjJfrukWEdVRXoKiy`

Thanks and Credits 🙏

NEO Foundation & NEO Global Development (NGD)
This project was strongly based on web3j latest on this commit. We are really thankful for it. 😃

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neow3j-docs's Issues

Document signatures in FAQ

Add Documentation for native Contracts' Interface Classes in Devpack

Create FAQ section

Include questions, such as:

call invoke vs invoke
handle iterators

improve docs for the Storage

Provide more examples about the Storage. Check the TODOs in the file docs/neo3_guides/compiler_devpack/devpack.md.

Update addresses for Donation

URL redirect list

Sometimes we change how neow3j docs pages are structured and then it breaks a bunch of URLs that were spread in the past.

Let's say, that, for example, we tweet about the Smart Contract testing and spread the following link:
https://neow3j.io/#/neo-n3/smart_contract_development/testing

But, in some months we change how the page is structured and we rename smart_contract_development to smart_contract_dev. Then the link above will be broken and will not lead to the correct page.

We would need to have a list of paths (i.e., /neo-n3-testing, etc) that we could change to pages. This would give us a lot of flexibility and less maintenance cost.

Create a tutorial on how to design smart contract's storage

We've got the following message on Discord:

Hey guys, sorry again, but another annoying question from this noob.

Basically, I'm trying to conceptually understand how to use the ''storage'' function, but am having trouble. I combed through the various documentation for different implementations but cannot find a satisfactory answer.

If storage is composed of ''key: value'' pairs, then how would multiple variables get attached to a certain address within storage? > For example, let's say I create a smart contract that accepts not only GAS from different users, but also their metadata as well (i.e. their first name, favorite color, etc), how would this metadata get placed into storage and tied to a specific user's address, since the key (from address, in this case) can only be attached to one variable at a time?

Would I need to create a prefix for each individual user and then create an object of ''key:value" pairs affiliated with each prefix/ user? Also, is it possible for keys to be overwritten?

Secondly, is there an easy way to broadly get a glimpse of what has been put into storage? I tried returning just Storage.get() but that doesn't work... Seeing what is in ''storage'' would help me to better design my getter methods to return what the data I'm looking for.

Anyways, any advice in this area would be really helpful. So far, I think the documentation for neow3j exceeds that of any of the other implementations I've used. Thanks again.

I believe it would make sense to discuss, in detail, how to design storage for a smart contract -- taking a real-world example, of a token, or smth like that.

Then, we could explore more advanced topics like: "based on X smart contract, how to migrate storage uppon smart contract's updates?"