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Module starknet-jvm

Starknet-jvm is a library allowing for easy interaction with the Starknet JSON-RPC nodes, including querying starknet state, executing transactions and deploying contracts.

Although written in Kotlin, Starknet-jvm has been created with compatibility with Java in mind.

Table of contents

Using provider

Provider is a facade for interacting with Starknet. JsonRpcProvider is a client which interacts with a Starknet full nodes like Pathfinder, Papyrus or Juno. It supports read and write operations, like querying the blockchain state or sending new transactions for execution.

import com.swmansion.starknet.provider.rpc.JsonRpcProvider;

public class Main {
    public static void main(String[] args) {
        JsonRpcProvider provider = new JsonRpcProvider(DemoConfig.rpcNodeUrl);
        
        Request<BlockWithTxs> request = provider.getBlockWithTxs(1);
        BlockWithTxs response = request.send();
    }
}

Reusing providers

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:

Provider provider = new JsonRpcProvider("https://your.node.url/rpc");
Account account1 = new StandardAccount(provider, accountAddress1, privateKey1);
Account account2 = new StandardAccount(provider, accountAddress2, privateKey2);

❌ Don't:

Provider provider1 = new JsonRpcProvider("https://your.node.url/rpc");
Account account1 = new StandardAccount(provider1, accountAddress1, privateKey1);
Provider provider2 = new JsonRpcProvider("https://your.node.url/rpc");
Account account2 = new StandardAccount(provider2, accountAddress2, privateKey2);

Creating account

StandardAccount is the default implementation of Account interface. It supports an account contract which proxies the calls to other contracts on Starknet.

Account can be created in two ways:

  • By constructor (It is required to provide an address and either private key or signer).

  • By methods Account.signDeployAccountV3() or Account.signDeployAccountV3()

There are some examples how to do it:

import com.swmansion.starknet.account.Account;
import com.swmansion.starknet.account.StandardAccount;
import com.swmansion.starknet.data.types.Felt;
import com.swmansion.starknet.data.types.StarknetChainId;

public class Main {
    public static void main(String[] args) {
        // If you don't have a private key, you can generate a random one
        Felt randomPrivateKey = StandardAccount.generatePrivateKey();

        // Create an instance of account which is already deployed
        // providing an address and a private key
        Account account = StandardAccount(
                Felt.fromHex("0x123"),
                Felt.fromHex("0x456"),
                provider,
                StarknetChainId.SEPOLIA
        );

        // It's possible to specify a signer
        Account accountWithSigner = StandardAccount(
                Felt.fromHex("0x123"),
                signer,
                provider,
                StarknetChainId.SEPOLIA
        );
    }
}

Transferring STRK tokens

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

import java.util.List;

public class Main {
    public static void main(String[] args) {
        Provider provider = new JsonRpcProvider("https://your.node.url");

        Account account = new StandardAccount(
                Felt.fromHex("0x123"),
                Felt.fromHex("0x456"),
                provider,
                StarknetChainId.SEPOLIA
        );

        Uint256 amount = new Uint256(new Felt(100));
        Felt recipientAccountAddress = Felt.fromHex("0x789");
        Felt strkContractAddress = Felt.fromHex("0x04718f5a0fc34cc1af16a1cdee98ffb20c31f5cd61d6ab07201858f4287c938d");
        Call call = Call.fromCallArguments(
                strkContractAddress,
                "transfer",
                List.of(recipientAccountAddress, amount)
        );

        Request<InvokeFunctionResponse> executeRequest = account.executeV3(call);
        InvokeFunctionResponse executeResponse = executeRequest.send();
    }
}

Making synchronous requests

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://your.node.url/rpc");

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

        System.out.println(response);
    }
}

Making asynchronous requests

It is also possible to make asynchronous requests. Request.sendAsync() returns a CompletableFuture that can be than handled in preferred way.

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://your.node.url/rpc");

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

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

Deploying account V3

import com.swmansion.starknet.account.Account;
import com.swmansion.starknet.account.StandardAccount;
import com.swmansion.starknet.crypto.StarknetCurve;
import com.swmansion.starknet.data.ContractAddressCalculator;
import com.swmansion.starknet.data.types.*;
import com.swmansion.starknet.provider.Provider;
import com.swmansion.starknet.provider.rpc.JsonRpcProvider;

import java.util.List;

public class Main {
public static void main(String[] args) {
// Create a provider for interacting with Starknet
Provider provider = new JsonRpcProvider("https://your.node.url/rpc");

        // Set up an account
        Felt privateKey = Felt.fromHex("0x123");
        Felt publicKey = StarknetCurve.getPublicKey(privateKey);
        // ⚠️ WARNING ⚠️ Both the account address and private key have examples values for demonstration purposes only.

        // Use the class hash of the desired account contract (i.e. the class hash of OpenZeppelin account contract)
        Felt classHash = Felt.fromHex("0x4d07e40e93398ed3c76981e72dd1fd22557a78ce36c0515f679e27f0bb5bc5f");
        Felt salt = new Felt(789);
        List<Felt> calldata = List.of(publicKey);

        Felt address = ContractAddressCalculator.calculateAddressFromHash(
                classHash,
                calldata,
                salt
        );

        StarknetChainId chainId = provider.getChainId().send();
        Account account = new StandardAccount(address, privateKey, provider, chainId);

        ResourceBounds l1ResourceBounds = new ResourceBounds(
                new Uint64(20000),
                new Uint128(120000000000L)
        );

        DeployAccountParamsV3 params = new DeployAccountParamsV3(Felt.ZERO, l1ResourceBounds);

        // Make sure to prefund the new account address

        DeployAccountTransactionV3 payload = account.signDeployAccountV3(classHash, calldata, salt, params, false);

        DeployAccountResponse response = provider.deployAccount(payload).send();

        // Make sure the address matches the calculated one
        System.out.println("Calculated address: " + address);
        System.out.println("Deployed address: " + response.getAddress());
        System.out.println("Are addresses equal: " + address.equals(response.getAddress()));
    }
}

Estimating fee for deploy account V3 transaction

import com.swmansion.starknet.account.Account;
import com.swmansion.starknet.account.StandardAccount;
import com.swmansion.starknet.crypto.StarknetCurve;
import com.swmansion.starknet.data.types.*;
import com.swmansion.starknet.provider.Provider;
import com.swmansion.starknet.provider.Request;
import com.swmansion.starknet.provider.rpc.JsonRpcProvider;


import java.util.List;

public class Main {
    public static void main(String[] args) {
        // Create a provider for interacting with Starknet
        Provider provider = new JsonRpcProvider("https://your.node.url/rpc");

        // Set up an account
        Felt privateKey = Felt.fromHex("0x1234");
        Felt publicKey = StarknetCurve.getPublicKey(privateKey);
        Felt accountAddress = Felt.fromHex("0x1236789");
        // ⚠️ WARNING ⚠️ Both the account address and private key are for demonstration purposes only.

        StarknetChainId chainId = provider.getChainId().send();
        Account account = new StandardAccount(accountAddress, privateKey, provider, chainId, CairoVersion.ZERO);

        DeployAccountParamsV3 params = new DeployAccountParamsV3(
                Felt.ZERO,
                ResourceBounds.ZERO
        );
        
        Felt salt = new Felt(2);
        List<Felt> calldata = List.of(publicKey);
        // Use the class hash of the desired account contract (i.e. the class hash of OpenZeppelin account contract)
        Felt classHash = Felt.fromHex("0x4d07e40e93398ed3c76981e72dd1fd22557a78ce36c0515f679e27f0bb5bc5f");
        DeployAccountTransactionV3 payloadForFeeEstimation = account.signDeployAccountV3(
                classHash,
                calldata,
                salt,
                params,
                true
        );
        
        Request<EstimateFeeResponseList> request = provider.getEstimateFee(List.of(payloadForFeeEstimation));
        EstimateFeeResponse response = request.send().getValues().get(0);

        System.out.println("The estimated fee is: " + response.getOverallFee().getValue() + ".");
    }
}

Deploying account V1

import com.swmansion.starknet.account.Account;
import com.swmansion.starknet.account.StandardAccount;
import com.swmansion.starknet.crypto.StarknetCurve;
import com.swmansion.starknet.data.ContractAddressCalculator;
import com.swmansion.starknet.data.types.DeployAccountResponse;
import com.swmansion.starknet.data.types.DeployAccountTransactionV1;
import com.swmansion.starknet.data.types.Felt;
import com.swmansion.starknet.data.types.StarknetChainId;
import com.swmansion.starknet.provider.Provider;
import com.swmansion.starknet.provider.rpc.JsonRpcProvider;

import java.util.List;

public class Main {
    public static void main(String[] args) {
        // Create a provider for interacting with Starknet
        Provider provider = new JsonRpcProvider("https://your.node.url/rpc");

        // Set up an account
        Felt privateKey = Felt.fromHex("0x123");
        Felt publicKey = StarknetCurve.getPublicKey(privateKey);
        // ⚠️ WARNING ⚠️ Both the account address and private key have examples values for demonstration purposes only.

        // Use the class hash of the desired account contract (i.e. the class hash of OpenZeppelin account contract)
        Felt classHash = Felt.fromHex("0x4d07e40e93398ed3c76981e72dd1fd22557a78ce36c0515f679e27f0bb5bc5f");
        Felt salt = new Felt(789);
        List<Felt> calldata = List.of(publicKey);

        Felt address = ContractAddressCalculator.calculateAddressFromHash(
                classHash,
                calldata,
                salt
        );

        StarknetChainId chainId = provider.getChainId().send();

        Account newAccount = new StandardAccount(address, privateKey, provider, chainId, CairoVersion.ZERO);

        // Make sure to prefund the new account address with at least maxFee

        // Create and sign deploy account transaction
        DeployAccountTransactionV1 payload = newAccount.signDeployAccountV1(
                classHash,
                calldata,
                salt,
                // 10*fee from estimate deploy account fee
                Felt.fromHex("0x11fcc58c7f7000")
        );

        DeployAccountResponse response = provider.deployAccount(payload).send();

        Thread.sleep(15000); // wait for deploy account tx to complete
        
        // Make sure the address matches the calculated one
        System.out.println("Calculated address: " + address);
        System.out.println("Deployed address: " + response.getAddress());
        System.out.println("Are addresses equal: " + address.equals(response.getAddress()));

    }
}

Estimating fee for deploy account V1 transaction

package org.example;

import com.swmansion.starknet.account.Account;
import com.swmansion.starknet.account.StandardAccount;
import com.swmansion.starknet.crypto.StarknetCurve;
import com.swmansion.starknet.data.ContractAddressCalculator;
import com.swmansion.starknet.data.types.*;
import com.swmansion.starknet.provider.Provider;
import com.swmansion.starknet.provider.Request;
import com.swmansion.starknet.provider.rpc.JsonRpcProvider;


import java.util.List;

public class Main {
    public static void main(String[] args) {
        // Create a provider for interacting with Starknet
        Provider provider = new JsonRpcProvider("https://your.node.url/rpc");

        // Set up an account
        Felt privateKey = Felt.fromHex("0x1234");
        Felt publicKey = StarknetCurve.getPublicKey(privateKey);

        // Use the class hash of the desired account contract (i.e. the class hash of OpenZeppelin account contract)
        Felt classHash = Felt.fromHex("0x4d07e40e93398ed3c76981e72dd1fd22557a78ce36c0515f679e27f0bb5bc5f");
        Felt salt = Felt.ONE;
        List<Felt> calldata = List.of(publicKey);
        Felt accountAddress = ContractAddressCalculator.calculateAddressFromHash(
                classHash,
                calldata,
                salt
        );
        // ⚠️ WARNING ⚠️ Both the account address and private key are for demonstration purposes only.

        StarknetChainId chainId = provider.getChainId().send();
        Account account = new StandardAccount(accountAddress, privateKey, provider, chainId, CairoVersion.ZERO);

        DeployAccountTransactionV1 payloadForFeeEstimation = account.signDeployAccountV1(
                classHash,
                calldata,
                salt,
                Felt.ZERO,
                Felt.ZERO,
                true
        );

        Request<EstimateFeeResponseList> request = provider.getEstimateFee(List.of(payloadForFeeEstimation));
        EstimateFeeResponse feeEstimate = request.send().getValues().get(0);

        System.out.println("The estimated fee is: " + feeEstimate.getOverallFee().getValue() + ".");
    }
}

Invoking contract: Transferring ETH

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

import java.util.ArrayList;
import java.util.List;

public class Main {
    public static void main(String[] args) {
        // Create a provider for interacting with Starknet
        Provider provider = new JsonRpcProvider("https://your.node.url/rpc");
        
        // Set up an account
        Felt privateKey = Felt.fromHex("0x123");
        Felt accountAddress = Felt.fromHex("0x1236789");
        // ⚠️ WARNING ⚠️ Both the account address and private key have examples values for demonstration purposes only.
        StarknetChainId chainId = provider.getChainId().send();
        Account account = new StandardAccount(accountAddress, privateKey, provider, chainId, CairoVersion.ZERO);

        Felt recipientAccountAddress = Felt.fromHex("0x987654321");
        Uint256 amount = new Uint256(new Felt(451));
        
        // Specify the contract address, in this example ERC-20 ETH contract is used
        Felt erc20ContractAddress = Felt.fromHex("0x049d36570d4e46f48e99674bd3fcc84644ddd6b96f7c741b1562b82f9e004dc7");
        
        // Create a call
        List<Felt> calldata = new ArrayList<>();
        calldata.add(recipientAccountAddress);
        calldata.addAll(amount.toCalldata());
        Call invokeCall = new Call(erc20ContractAddress, "transfer", calldata);

        // Create and sign invoke transaction
        Request<InvokeFunctionResponse> executeRequest = account.executeV3(invokeCall);

        // account.executeV3(call) estimates the fee automatically
        // If you want to estimate the fee manually, please refer to the "Estimate Fee" example
        
        // Send the transaction
        InvokeFunctionResponse executeResponse = executeRequest.send();

        Thread.sleep(20000); // wait for invoke tx to complete

        // Make sure that the transaction succeeded
        Request<? extends TransactionReceipt> invokeReceiptRequest = provider.getTransactionReceipt(executeResponse.getTransactionHash());
        TransactionReceipt invokeReceipt = invokeReceiptRequest.send();

        System.out.println("Was invoke transaction accepted? " + invokeReceipt.isAccepted() + ".");
    }
}

Estimating fee for invoke V3 transaction

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

import java.util.List;

public class Main {
    public static void main(String[] args) {
        // Create a provider for interacting with Starknet
        Provider provider = new JsonRpcProvider("https://your.node.url/rpc");

        // Set up an account
        Felt privateKey = Felt.fromHex("0x1234");
        Felt accountAddress = Felt.fromHex("0x1236789");
        // ⚠️ WARNING ⚠️ Both the account address and private key are for demonstration purposes only.

        StarknetChainId chainId = provider.getChainId().send();
        Account account = new StandardAccount(accountAddress, privateKey, provider, chainId, CairoVersion.ZERO);

        Felt contractAddress = Felt.fromHex("0x123456789");

        // In this example we want to increase the balance by 10
        Call call = new Call(contractAddress, "increase_balance", List.of(new Felt(10)));

        Request<EstimateFeeResponseList> request = account.estimateFeeV3(
                call,
                false
        );

        EstimateFeeResponse feeEstimate = request.send().getValues().get(0);
        System.out.println("The estimated fee is: " + feeEstimate.getOverallFee().getValue() + ".");
    }
}

Calling contract: Fetching ETH balance

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

import java.util.List;

public class Main {
    public static void main(String[] args) {
        // Create a provider for interacting with Starknet
        Provider provider = new JsonRpcProvider("https://your.node.url/rpc");
        
        // Set up an account
        Felt privateKey = Felt.fromHex("0x123");
        Felt accountAddress = Felt.fromHex("0x1236789");
        // ⚠️ WARNING ⚠️ Both the account address and key are for demonstration purposes only.

        StarknetChainId chainId = provider.getChainId().send();
        Account account = new StandardAccount(accountAddress, privateKey, provider, chainId, CairoVersion.ZERO);

        // Specify the contract address, in this example ETH ERC20 contract is used
        Felt contractAddress = Felt.fromHex("0x049d36570d4e46f48e99674bd3fcc84644ddd6b96f7c741b1562b82f9e004dc7");

        // Create a call
        List<Felt> calldata = List.of(account.getAddress());
        Call call = new Call(contractAddress, "balanceOf", calldata);
        Request<FeltArray> request = provider.callContract(call);

        // Send the call request
        List<Felt> response = request.send();

        // Output value's type is Uint256 and is represented by two Felt values
        Uint256 balance = new Uint256(response.get(0), response.get(1));

        System.out.println("Balance: " + balance.toString() + ".");
    }
}

Making multiple calls: get multiple transactions data in one request

package com.example.javademo;

import com.swmansion.starknet.data.types.RequestResult;
import com.swmansion.starknet.provider.rpc.JsonRpcProvider;
import com.swmansion.starknet.service.http.requests.HttpBatchRequest;

import java.util.List;

public class Abc {
    public static void main(String[] args) {
        // Create a provider for interacting with Starknet
        JsonRpcProvider provider = new JsonRpcProvider("https://your.node.url/rpc");

        int blockNumber = provider.getBlockNumber().send().getValue();

        // Batch RPC requests
        HttpBatchRequest request = provider.batchRequests(
                provider.getTransactionByBlockIdAndIndex(blockNumber, 0),
                provider.getTransaction(invokeTransactionHash),
                provider.getTransaction(declareTransactionHash),
                provider.getTransaction(deployAccountTransactionHash)
        );

        // Create and send the batch request
        List<RequestResult> response = request.send();
    }
}

Making multiple calls of different types in one request

import com.swmansion.starknet.data.types.*;
import com.swmansion.starknet.data.types.RequestResult;
import com.swmansion.starknet.provider.rpc.JsonRpcProvider;
import com.swmansion.starknet.service.http.requests.HttpBatchRequest;

import java.util.List;

import static com.swmansion.starknet.data.Selector.selectorFromName;

public class Main {
    public static void main(String[] args) {
        // Create a provider for interacting with Starknet
        JsonRpcProvider provider = new JsonRpcProvider("https://your.node.url/rpc");

        // Batch any RPC requests
        // Get block hash and number + Check the initial value of `balance` in contract
        HttpBatchRequest mixedRequest = provider.batchRequestsAny(
                provider.getBlockHashAndNumber(),
                provider.getStorageAt(Felt.fromHex("0x123"), selectorFromName("balance"))
        );

        // Create and send the batch request
        List<RequestResult> mixedResponse = mixedRequest.send();

        GetBlockHashAndNumberResponse blockHashAndNumber = (GetBlockHashAndNumberResponse) mixedResponse.get(0).getOrNull();
        Felt contractBalance = (Felt) mixedResponse.get(1).getOrNull();

        System.out.println("Block hash: " + blockHashAndNumber.getBlockHash() + ".");
        System.out.println("Initial contract balance: " + contractBalance.getValue() + ".");
    }
}

Declaring Cairo 1/2 contract V3

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

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.List;

public class Main {
    public static void main(String[] args) throws IOException, InterruptedException {
        // Create a provider for interacting with Starknet
        Provider provider = new JsonRpcProvider("https://your.node.url/rpc");

        StarknetChainId chainId = provider.getChainId().send();

        // Set up an account
        Felt privateKey = Felt.fromHex("0x1234");
        Felt accountAddress = Felt.fromHex("0x1236789");
        // ⚠️ WARNING ⚠️ Both the account address and private key are for demonstration purposes only.
        Account account = new StandardAccount(accountAddress, privateKey, provider, chainId, CairoVersion.ZERO);

        // Import a compiled contract
        Path contractPath = Paths.get("contract.sierra.json");
        Path casmPath = Paths.get("contract.casm.json");
        String contractCode = String.join("", Files.readAllLines(contractPath));
        String casmCode = String.join("", Files.readAllLines(casmPath));
        Cairo1ContractDefinition contractDefinition = new Cairo1ContractDefinition(contractCode);
        CasmContractDefinition casmContractDefinition = new CasmContractDefinition(casmCode);
        Felt nonce = account.getNonce().send();

        // Estimate fee for declaring a contract
        DeclareTransactionV3 declareTransactionPayloadForFeeEstimate = account.signDeclareV3(contractDefinition, casmContractDefinition, new DeclareParamsV3(nonce, ResourceBounds.ZERO), true);
        Request<EstimateFeeResponseList> feeEstimateRequest = provider.getEstimateFee(List.of(declareTransactionPayloadForFeeEstimate));
        EstimateFeeResponse feeEstimate = feeEstimateRequest.send().getValues().get(0);

        // Make sure to prefund the account with enough funds to cover the fee for declare transaction

        // Declare a contract
        ResourceBounds l1ResourceBounds = feeEstimate.toResourceBounds(1.5, 1.5).getL1Gas();
        DeclareParamsV3 params = new DeclareParamsV3(nonce, l1ResourceBounds);
        DeclareTransactionV3 declareTransactionPayload = account.signDeclareV3(contractDefinition, casmContractDefinition, params, false);

        Request<DeclareResponse> request = provider.declareContract(declareTransactionPayload);
        DeclareResponse response = request.send();

        Thread.sleep(60000); // wait for declare tx to complete

        TransactionReceipt receipt = provider.getTransactionReceipt(response.getTransactionHash()).send();
        System.out.println("Was transaction accepted? " + receipt.isAccepted() + ".");
    }
}

Estimating fee for declare V3 transaction

import com.swmansion.starknet.account.Account;
import com.swmansion.starknet.account.StandardAccount;
import com.swmansion.starknet.crypto.StarknetCurve;
import com.swmansion.starknet.data.types.*;
import com.swmansion.starknet.provider.Provider;
import com.swmansion.starknet.provider.Request;
import com.swmansion.starknet.provider.rpc.JsonRpcProvider;


import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Collections;
import java.util.List;

public class Main {
    public static void main(String[] args) throws IOException {
        // Create a provider for interacting with Starknet
        Provider provider = new JsonRpcProvider("https://your.node.url/rpc");

        // Set up an account
        Felt privateKey = Felt.fromHex("0x1234");
        Felt publicKey = StarknetCurve.getPublicKey(privateKey);
        Felt accountAddress = Felt.fromHex("0x1236789");
        // ⚠️ WARNING ⚠️ Both the account address and private key are for demonstration purposes only.

        StarknetChainId chainId = provider.getChainId().send();
        Account account = new StandardAccount(accountAddress, privateKey, provider, chainId, CairoVersion.ZERO);

        // Import a compiled contract
        Path contractPath = Paths.get("contract.sierra.json");
        Path casmPath = Paths.get("contract.casm.json");
        String contractCode = String.join("", Files.readAllLines(contractPath));
        String casmCode = String.join("", Files.readAllLines(casmPath));
        Cairo1ContractDefinition contractDefinition = new Cairo1ContractDefinition(contractCode);
        CasmContractDefinition casmContractDefinition = new CasmContractDefinition(casmCode);
        Felt nonce = account.getNonce().send();

        DeclareParamsV3 params = new DeclareParamsV3(
                nonce,
                ResourceBounds.ZERO
        );

        DeclareTransactionV3 payload = account.signDeclareV3(
                contractDefinition,
                casmContractDefinition,
                params,
                true
        );

        Request<EstimateFeeResponseList> request = provider.getEstimateFee(List.of(payload), Collections.emptySet());
        EstimateFeeResponse response = request.send().getValues().get(0);

        System.out.println("The estimated fee is: " + response.getOverallFee().getValue() + ".");
    }
}

Declaring Cairo 1/2 contract V2

package org.example;

import com.swmansion.starknet.account.Account;
import com.swmansion.starknet.account.StandardAccount;
import com.swmansion.starknet.crypto.StarknetCurve;
import com.swmansion.starknet.data.types.*;
import com.swmansion.starknet.provider.Provider;
import com.swmansion.starknet.provider.Request;
import com.swmansion.starknet.provider.rpc.JsonRpcProvider;


import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

public class Main {
    public static void main(String[] args) throws IOException, InterruptedException {
        // Create a provider for interacting with Starknet
        Provider provider = new JsonRpcProvider("https://your.node.url/rpc");

        // Set up an account
        Felt privateKey = Felt.fromHex("0x1234");
        Felt publicKey = StarknetCurve.getPublicKey(privateKey);
        Felt accountAddress = Felt.fromHex("0x1236789");
        // ⚠️ WARNING ⚠️ Both the account address and private key are for demonstration purposes only.

        StarknetChainId chainId = provider.getChainId().send();
        Account account = new StandardAccount(accountAddress, privateKey, provider, chainId, CairoVersion.ZERO);

        // Import a compiled contract
        Path contractPath = Paths.get("contract.sierra.json");
        Path casmPath = Paths.get("contract.casm.json");
        String contractCode = String.join("", Files.readAllLines(contractPath));
        String casmCode = String.join("", Files.readAllLines(casmPath));
        Cairo1ContractDefinition contractDefinition = new Cairo1ContractDefinition(contractCode);
        CasmContractDefinition casmContractDefinition = new CasmContractDefinition(casmCode);
        Felt nonce = account.getNonce().send();

        DeclareTransactionV2 payload = account.signDeclareV2(
                contractDefinition,
                casmContractDefinition,
                new ExecutionParams(nonce, new Felt(1000000000000000L)),
                false
        );
        Request<DeclareResponse> request = provider.declareContract(payload);
        DeclareResponse response = request.send();

        Thread.sleep(60000);

        TransactionReceipt receipt = provider.getTransactionReceipt(response.getTransactionHash()).send();

        System.out.println("Was transaction accepted? " + receipt.isAccepted() + ".");
    }
}

Estimating fee for declare V2 transaction

import com.swmansion.starknet.account.Account;
import com.swmansion.starknet.account.StandardAccount;
import com.swmansion.starknet.crypto.StarknetCurve;
import com.swmansion.starknet.data.types.*;
import com.swmansion.starknet.provider.Provider;
import com.swmansion.starknet.provider.Request;
import com.swmansion.starknet.provider.rpc.JsonRpcProvider;


import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Collections;
import java.util.List;

public class Main {
    public static void main(String[] args) throws IOException, InterruptedException {
        // Create a provider for interacting with Starknet
        Provider provider = new JsonRpcProvider("https://your.node.url/rpc");

        // Set up an account
        Felt privateKey = Felt.fromHex("0x1234");
        Felt publicKey = StarknetCurve.getPublicKey(privateKey);
        Felt accountAddress = Felt.fromHex("0x1236789");
        // ⚠️ WARNING ⚠️ Both the account address and private key are for demonstration purposes only.

        StarknetChainId chainId = provider.getChainId().send();
        Account account = new StandardAccount(accountAddress, privateKey, provider, chainId, CairoVersion.ZERO);

        // Import a compiled contract
        Path contractPath = Paths.get("contract.sierra.json");
        Path casmPath = Paths.get("contract.casm.json");
        String contractCode = String.join("", Files.readAllLines(contractPath));
        String casmCode = String.join("", Files.readAllLines(casmPath));

        Cairo1ContractDefinition contractDefinition = new Cairo1ContractDefinition(contractCode);
        CasmContractDefinition casmContractDefinition = new CasmContractDefinition(casmCode);
        Felt nonce = account.getNonce().send();

        DeclareTransactionV2 payload = account.signDeclareV2(
                contractDefinition,
                casmContractDefinition,
                new ExecutionParams(nonce,Felt.ZERO),
                true
        );
        Request<EstimateFeeResponseList> request = provider.getEstimateFee(List.of(payload), Collections.emptySet());
        EstimateFeeResponseList response = request.send();
        EstimateFeeResponse feeEstimate = response.getValues().get(0);
        
        System.out.println("The estimated fee is: " + feeEstimate.getOverallFee().getValue() + ".");
    }
}

Package com.swmansion.starknet.account

Account interface is used to send Starknet transactions for execution. Its base implementation is StandardAccount.

Example usage of StandardAccount

Package com.swmansion.starknet.crypto

Cryptography and signature related classes. This is a low level module. Recommended way of using is through Signer and Account implementations.

Package com.swmansion.starknet.data

Data classes representing Starknet objects and utilities for handling them.

Package com.swmansion.starknet.data.types

Data classes representing Starknet objects and transactions.

Package com.swmansion.starknet.deployercontract

Classes for interacting with Universal Deployer Contract (UDC).

Package com.swmansion.starknet.provider

Provider interface and its implementations.

Package com.swmansion.starknet.provider.exceptions

Exceptions thrown by the Starknet providers.

Request.send() throws RequestFailedException unchecked exception. It can optionally be handled. In the case of Request.sendAsync(), an exception would have to be handled in the returned CompletableFuture.

Package com.swmansion.starknet.provider.rpc

Provider implementing the JSON-RPC interface to communicate with the network.

Package com.swmansion.starknet.service.http

Http service used to communicate with Starknet.

You can create a OkHttpService yourself and pass it whenever creating a provider. This way your whole application can use a single OkHttpClient. Read more here.

import com.swmansion.starknet.service.http.OkHttpService;

// (...)

OkHttpClient httpClient = new OkHttpClient();
OkHttpService httpService = new OkHttpService(httpClient);

Package com.swmansion.starknet.signer

Signer interface and its implementations for manually signing transactions to be sent to Starknet. Recommended way of using Signer is through an Account.

// Create a signer
Signer signer = ...
        
// Sign a transaction
List<Felt> signature = signer.signTransaction(tx);

// Get a public key
Felt publicKey = signer.getPublicKey();