Build your Hedera client
Build your client to interact with any of the Hedera network nodes. Mainnet, testnet, and previewnet are the three Hedera networks you can submit transactions and queries to.
V1
Method | Type | Description |
Client.forPreviewnet() | | Constructs a Hedera client pre-configured for Previewnet access |
Client.forTestnet() | | Constructs a Hedera client pre-configured for Testnet access |
Client.forMainnet() | | Constructs a Hedera client pre-configured for Mainnet access |
Client.fromFile(<file>) | File | Configures a client from a file |
Client.fromFile(<fileName>) | String | Constructs a network from a file |
Client.fromJson(<json>) | String | Configure a client from the given JSON string |
Client.fromJson(<json>) | Reader | Configure a client from the given JSON reader |
Client.replaceNodes(<nodes>) | Map<AccountId, String> | Replaces nodes in the network |
Java
// From a pre-configured network
Client client = Client.forTestnet();
//Replace nodes
Map<AccountId, String> nodes = new HashMap<>();
nodes.put(AccountId.fromString("0.0.10"), "34.94.106.61:50211" ,);
client.replaceNodes(nodes);
//v1.3.2
JavaScript
// From a pre-configured network
const client = Client.forTestnet();
//v1.4.4
The operator is the account that will, by default, pay the transaction fee for transactions and queries built with this client. The operator account ID is used to generate the default transaction ID for all transactions executed with this client. The operator private key is used to sign all transactions executed by this client.
Method | Type |
|---|---|
Client.<network>.setOperator(<accountId, privateKey>) | AccountId, PrivateKey |
Client.<network>.setOperatorWith(<accountId, privateKey, transactionSigner>) | AccountId, PrivateKey, Function<byte[ ], byte [ ]> |
Java
JavaScript
Go
// Operator account ID and private key from string value
AccountId OPERATOR_ID = AccountId.fromString("0.0.96928");
Ed25519PrivateKey OPERATOR_KEY = PrivateKey.fromString("302e020100300506032b657004220420b9c3ebac81a72aafa5490cc78111643d016d311e60869436fbb91c7330796928");
// Pre-configured client for test network (testnet)
Client client = Client.forTestnet()
//Set the operator with the operator ID and operator key
client.setOperator(OPERATOR_ID, OPERATOR_KEY);
// Operator account ID and private key from string value
const OPERATOR_ID = AccountId.fromString("0.0.96928");
const OPERATOR_KEY = PrivateKey.fromString("302e020100300506032b657004220420b9c3ebac81a72aafa5490cc78111643d016d311e60869436fbb91c7330796928");
// Pre-configured client for test network (testnet)
const client = Client.forTestnet()
//Set the operator with the operator ID and operator key
client.setOperator(OPERATOR_ID, OPERATOR_KEY);
// Operator account ID and private key from string value
operatorAccountID, err := hedera.AccountIDFromString("0.0.96928")
if err != nil {
panic(err)
}
operatorKey, err := hedera.PrivateKeyFromString("302e020100300506032b65700422042012a4a4add3d885bd61d7ce5cff88c5ef2d510651add00a7f64cb90de33596928")
if err != nil {
panic(err)
}
// Pre-configured client for test network (testnet)
client := hedera.ClientForTestnet()
//Set the operator with the operator ID and operator key
client.SetOperator(operatorAccountID, operatorKey)
The .env file is created in the root directory of the SDK. The .env file stores account ID and the associated private key information to reference throughout your code. You will need to import the relevant dotenv module to your project files. The sample .env file may look something like this:
.env
OPERATOR_ID= 0.0.9410
OPERATOR_KEY= 302e020100300506032b65700422042012a4a4add3d885bd61d7ce5cff88c5ef2d510651add00a7f64cb90de3359bc5e
Java
JavaScript
Go
//Grab the account ID and private key of the operator account from the .env file
AccountId OPERATOR_ID = AccountId.fromString(Objects.requireNonNull(Dotenv.load().get("OPERATOR_ID")));
Ed25519PrivateKey OPERATOR_KEY = Ed25519PrivateKey.fromString(Objects.requireNonNull(Dotenv.load().get("OPERATOR_KEY")));
// Pre-configured client for test network (testnet)
Client client = Client.forTestnet()
//Set the operator with the operator ID and operator key
client.setOperator(OPERATOR_ID, OPERATOR_KEY);
//Grab the account ID and private key of the operator account from the .env file
const operatorAccount = process.env.OPERATOR_ID;
const operatorPrivateKey = process.env.OPERATOR_KEY;
// Pre-configured client for test network (testnet)
const client = Client.forTestnet()
//Set the operator with the operator ID and operator key
client.setOperator(operatorAccount, operatorPrivateKey );
err := godotenv.Load(".env")
if err != nil {
panic(fmt.Errorf("Unable to load environment variables from demo.env file. Error:\n%v\n", err))
}
//Get the operator ID and operator key
OPERATOR_ID := os.Getenv("OPERATOR_ID")
OPERATOR_KEY := os.Getenv("OPERATOR_KEY")
operatorAccountID, err := hedera.AccountIDFromString(OPERATOR_ID)
if err != nil {
panic(err)
}
operatorKey, err := hedera.PrivateKeyFromString(OPERATOR_KEY)
if err != nil {
panic(err)
}
The max transaction fee and max query payment are both set to 100_000_000 tinybar (1 hbar). This amount can be modified by using
setDefaultMaxTransactionFee()and setDefaultMaxQueryPayment().V1
Method | Type | Description |
|---|---|---|
setMaxTransactionFee(<fee>) | Hbar/long | The maximum transaction fee the client is willing to pay. Default: 1 hbar |
setMaxQueryPayment(<maxQueryPayment>) | Hbar/long | The maximum query payment the client will pay. Default: 1 hbar |
Java
Client client = Client.forTestnet();
client.setOperator(OPERATOR_ID, OPERATOR_KEY);
client.setMaxTransactionFee(new Hbar(2));
//v1.3.2
JavaScript
// For test network (testnet)
const client = Client.forTestnet()
//Set the operator and operator private key
client.setOperator(OPERATOR_ID, OPERATOR_KEY);
//Set the max transaction fee the client is willing to pay to 2 hbars
client.setMaxTransactionFee(new Hbar(2));
//v1.4.4
Last modified 3mo ago