☕ starknet jvm ☕

Starknet SDK for JVM languages:

• Java
• Kotlin
• Scala
• Clojure
• Groovy

Table of contents

• Table of contents
• Installation
• Documentation
• Example usages
  • Making synchronous requests
  • Making asynchronous requests
  • Standard flow examples
• Demo applications
  • Android demo
  • Java demo
• Reusing http clients
• Development
  • Hooks
• Running tests
  • Prerequisites
  • Regular Tests
  • Network Tests
  • Ensuring idiomatic Java code
• Building documentation

Installation

Select the latest version from the list and follow installation instructions.

Documentation

Documentation is provided in two formats:

• Java and other jvm languages
• Kotlin

Example usages

Making synchronous requests

import com.swmansion.starknet.account.Account;
import com.swmansion.starknet.account.StandardAccount;
import com.swmansion.starknet.data.types.BlockTag;
import com.swmansion.starknet.data.types.Felt;
import com.swmansion.starknet.provider.Provider;
import com.swmansion.starknet.provider.Request;
import com.swmansion.starknet.provider.rpc.JsonRpcProvider;

public class Main {
    public static void main(String[] args) {
        // Create a provider for interacting with Starknet
        Provider provider = new JsonRpcProvider("https://example-node-url.com/rpc");
        
        // Create an account interface
        Felt accountAddress = Felt.fromHex("0x13241455");
        Felt privateKey = Felt.fromHex("0x425125");
        Account account = new StandardAccount(provider, accountAddress, privateKey);

        // Make a request
        Felt contractAddress = Felt.fromHex("0x42362362436");
        Felt storageKey = Felt.fromHex("0x13241253414");
        Request<Felt> request = account.getStorageAt(contractAddress, storageKey, BlockTag.LATEST);
        Felt response = request.send();

        System.out.println(response);
    }
}

Making asynchronous requests

import com.swmansion.starknet.account.Account;
import com.swmansion.starknet.account.StandardAccount;
import com.swmansion.starknet.data.types.BlockTag;
import com.swmansion.starknet.data.types.Felt;
import com.swmansion.starknet.provider.Provider;
import com.swmansion.starknet.provider.Request;
import com.swmansion.starknet.provider.rpc.JsonRpcProvider;

import java.util.concurrent.CompletableFuture;

public class Main {
    public static void main(String[] args) {
        // Create a provider for interacting with Starknet
        Provider provider = new JsonRpcProvider("https://example-node-url.com/rpc");
        
        // Create an account interface
        Felt accountAddress = Felt.fromHex("0x13241455");
        Felt privateKey = Felt.fromHex("0x425125");
        Account account = new StandardAccount(provider, accountAddress, privateKey);

        // Make a request
        Felt contractAddress = Felt.fromHex("0x42362362436");
        Felt storageKey = Felt.fromHex("0x13241253414");
        Request<Felt> request = account.getStorageAt(contractAddress, storageKey, BlockTag.LATEST);
        CompletableFuture<Felt> response = request.sendAsync();

        response.thenAccept(System.out::println);
    }
}

Standard flow examples

• Deploying account
• Invoking contract: Transferring ETH
• Calling contract: Fetching ETH balance
• Declaring Cairo 1/2 contract

Demo applications

These demo apps can be used with any Starknet RPC node, including devnet. They are intended for demonstration/testing purposes only.

Android demo

Java demo

Reusing http clients

Make sure you don't create a new provider every time you want to use one. Instead, you should reuse existing instance. This way you reuse connections and thread pools.

✅ Do:

var provider = new JsonRpcProvider("https://example-node-url.com/rpc");
var account1 = new StandardAccount(provider, accountAddress1, privateKey1);
var account2 = new StandardAccount(provider, accountAddress2, privateKey2);

❌ Don't:

var provider1 = new JsonRpcProvider("https://example-node-url.com/rpc");
var account1 = new StandardAccount(provider1, accountAddress1, privateKey1);
var provider2 = new JsonRpcProvider("https://example-node-url.com/rpc");
var account2 = new StandardAccount(provider2, accountAddress2, privateKey2);

Development

Hooks

Run

./gradlew installKotlinterPrePushHook

Running tests

Prerequisites

• starknet-devnet-rs
  • Since it has yet to be released, you will need to build it manually and set DEVNET_PATH environment variable that points to a binary:

    DEVNET_PATH=/path/to/starknet-devnet-rs/target/release/starknet-devnet

  • You can do so by using environment variables in your system or IDE, or by sourcing an .env file. Refer to the example config found in test_variables.env.example.
• starknet-foundry - provides sncast cli
• asdf version manager and asdf scarb plugin

Regular Tests

Use the following command to run tests:

./gradlew :lib:test

Network Tests

Running tests on networks requires a valid configuration. It can be set using environment variables in your system or IDE, or by sourcing an .env file. Refer to the example config found in test_variables.env.example. To select the network, please set the NETWORK_TEST_NETWORK_NAME environment variable. Currenty, the allowed options are:

• SEPOLIA_TESTNET
• SEPOLIA_INTEGRATION

Note: The transition of network tests from GOERLI to SEPOLIA networks results in a current limitation of v3 tests. To properly configure your network, ensure the following variables are set with the NETWORK_NAME_ prefix:

• RPC_URL - url of your RPC node
• ACCOUNT_ADDRESS and PRIVATE_KEY - address and private key of your account

Additionally, you can also set:

• CONST_NONCE_ACCOUNT_ADDRESS and CONST_NONCE_PRIVATE_KEY - address and private key exclusively for non-gas network tests, preventing potential inconsistencies (sometimes, getNonce may report higher nonce than expected). Recommended for reliable non-gas testing. These default to ACCOUNT_ADDRESS and PRIVATE_KEY if not set.
• ACCOUNT_CAIRO_VERSION - Cairo version of the ACCOUNT_ADDRESS and CONST_NONCE_ACCOUNT_ADDRESS accounts. Defaults to 0.

Network tests are disabled by default. To enable them, you can set the environment variable:

NETWORK_TEST_MODE=non_gas

Some network tests require gas and are disabled by default. If you want to run them as well, you can set:

NETWORK_TEST_MODE=all

⚠️ WARNING ⚠️ Please be aware that in that case your account address must have a pre-existing balance as these tests will consume some funds.

Alternatively, you can use flag to specify whether to run network and gas tests:

./gradlew :lib:test -PnetworkTestMode=non_gas
./gradlew :lib:test -PnetworkTestMode=all

Flag takes precendece over the environment variable if both are set.

Ensuring idiomatic Java code

We want this library to be used by both kotlin & java users. In order to ensure a nice API for java always follow those rules:

1. When using file level functions use @file:JvmName(NAME) to ensure a nice name without Kt suffix.
2. When using a companion object mark every property/function with @JvmStatic. This way they are accessible as static from the class. Without it Class.INSTANCE would have to be used.
3. When defining an immutable constant use @field:JvmField. This makes them static properties without getters/setters in java.
4. If you are not sure how something would work in java just create a new java class, import your code and check yourself.
5. Avoid using default arguments. It is better to overload a function and specify defaults there.

Building documentation

Documentation is written in Kdoc format and markdown and is generated using Dokka. Execute following commands from /lib to build docs.

• ./gradlew dokkaHtml to build kotlin format docs
• ./gradlew dokkaHtmlJava to build java format docs

Generated documentation can be found in their respective folders inside /build/dokka.