Smart Contract Client¶

SmartContractClient provides APIs for managing smart contracts on a Hiero network, including contract deployment and function execution.

Note

Smart contract operations that submit transactions to the Hiero network require HBAR to pay transaction fees. The configured operator account is used as the transaction payer and must have sufficient HBAR balance.

Methods¶

Method	Description
`createContract(String fileId, ContractParam<?>... constructorParams)`	Creates a smart contract using bytecode stored in a file ID string.
`createContract(FileId fileId, ContractParam<?>... constructorParams)`	Creates a smart contract using an existing bytecode file.
`createContract(byte[] contents, ContractParam<?>... constructorParams)`	Creates a smart contract using bytecode contents.
`createContract(Path pathToBin, ContractParam<?>... constructorParams)`	Creates a smart contract using a bytecode file path.
`createContract(String fileId, Hbar maxTransactionFee, int gas, ContractParam<?>... constructorParams)`	Creates a smart contract using bytecode stored in a file ID string with a custom maximum transaction fee and gas limit.
`createContract(FileId fileId, Hbar maxTransactionFee, int gas, ContractParam<?>... constructorParams)`	Creates a smart contract using an existing bytecode file with a custom maximum transaction fee and gas limit.
`createContract(byte[] contents, Hbar maxTransactionFee, int gas, ContractParam<?>... constructorParams)`	Creates a smart contract using bytecode contents with a custom maximum transaction fee and gas limit.
`createContract(Path pathToBin, Hbar maxTransactionFee, int gas, ContractParam<?>... constructorParams)`	Creates a smart contract using a bytecode file path with a custom maximum transaction fee and gas limit.
`callContractFunction(String contractId, String functionName, ContractParam<?>... params)`	Executes a contract function using a contract ID string.
`callContractFunction(ContractId contractId, String functionName, ContractParam<?>... params)`	Executes a contract function using a contract ID.
`callContractFunction(String contractId, String functionName, Hbar maxTransactionFee, int gas, ContractParam<?>... params)`	Executes a smart contract function using a contract ID string with a custom maximum transaction fee and gas limit.
`callContractFunction(ContractId contractId, String functionName, Hbar maxTransactionFee, int gas, ContractParam<?>... params)`	Executes a smart contract function using a contract ID with a custom maximum transaction fee and gas limit.
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Create Contract¶

Deploys a smart contract to the Hiero network.

createContract(FileId fileId, ContractParam<?>... constructorParams)

FileId fileId =
    FileId.fromString("0.0.1234");


ContractId contractId =
    smartContractClient.createContract(
        fileId,
        ContractParam.string("Hello Hiero")
    );

createContract(byte[] contents, ContractParam<?>... constructorParams)

byte[] bytecode =
    Files.readAllBytes(
        Path.of("contract.bin")
    );

ContractId contractId =
    smartContractClient.createContract(
        bytecode,
        ContractParam.string("Hello Hiero")
    );

createContract(Path pathToBin, ContractParam<?>... constructorParams)

ContractId contractId =
    smartContractClient.createContract(
        Path.of("contract.bin"),
        ContractParam.string("Hello Hiero")
    );

Info

When maxTransactionFee and gas are not specified, the client uses 100 HBAR as the default maximum transaction fee and 5_000_000 as the default gas limit. You can also override these values by using the overload that accepts maxTransactionFee and gas.

createContract(FileId fileId, Hbar maxTransactionFee, int gas, ContractParam<?>... constructorParams)

FileId fileId =
    FileId.fromString("0.0.1234");

ContractId contractId =
    smartContractClient.createContract(
        fileId,
        Hbar.from(20),
        10_000_000,
        ContractParam.string("Hello Hiero")
    );

Call Contract Function¶

Executes a function on an existing smart contract.

callContractFunction(ContractId contractId, String functionName, ContractParam<?>... params)

ContractId contractId =
    ContractId.fromString("0.0.5678");

ContractCallResult result =
    smartContractClient.callContractFunction(
        contractId,
        "getValue",
        ContractParam.string("Hello Hiero")
    );

Info

When maxTransactionFee and gas are not specified, the client uses 100 HBAR as the default maximum transaction fee and 5_000_000 as the default gas limit. You can also override these values by using the overload that accepts maxTransactionFee and gas.

callContractFunction(ContractId contractId, String functionName, Hbar maxTransactionFee, int gas, ContractParam<?>... params)

ContractId contractId =
    ContractId.fromString("0.0.5678");

ContractCallResult result =
    smartContractClient.callContractFunction(
        contractId,
        "getValue",
        Hbar.from(20),
        10_000_000,
        ContractParam.string("Hello Hiero")
    );

Warning

The maximum gas that can be specified for a contract execution is 15_000_000.
The maxTransactionFee and gas values determine the maximum amount you are willing to pay for the transaction. If the required gas exceeds the specified limit or the maximum transaction fee is too low, the transaction may fail.

Tip

See the Contract Parameters documentation for all supported Solidity parameter types, including strings, addresses, booleans, bytes, and numeric types.