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.
For a predefined network (preview, testnet, and mainnet), the mirror node client is configured to the corresponding network mirror node.
Method | Type | Description |
| ​ | Constructs a Hedera client pre-configured for Previewnet access |
| ​ | Constructs a Hedera client pre-configured for Testnet access |
| ​ | Constructs a Hedera client pre-configured for Mainnet access |
| Map<String, AccountId> | Construct a client given a set of nodes. It is the responsibility of the caller to ensure that all nodes in the map are part of the same Hedera network. Failure to do so will result in undefined behavior. |
| String | Configure a client from the given JSON string |
| Reader | Configure a client from the given JSON reader |
| File | Configure a client based on a JSON file. |
| String | Configure a client based on a JSON file at the given path. |
| List<String>) | Define a specific mirror network node(s) ip:port in string format |
Java// From a pre-configured networkClient client = Client.forTestnet();​//For a specified networkMap<String, AccountId> nodes = new HashMap<>();nodes.put("34.94.106.61:50211" ,AccountId.fromString("0.0.10"));​Client.forNetwork(nodes);​//v2.0.0
JavaScript// From a pre-configured networkconst client = Client.forTestnet();​//For a specified networkconst nodes = {"35.237.200.180:50211": new AccountId(3)}const client = Client.forNetwork(nodes);​//v2.0.7
Go// From a pre-configured networkclient := hedera.ClientForTestnet()​//For a specified networknode := map[string]AccountID{"34.94.106.61:50211": {Account: 10}}​client := Client.forNetwork(nodes)​//v2.0.0
Method | Type | Description |
| ​ | Constructs a Hedera client pre-configured for Previewnet access |
| ​ | Constructs a Hedera client pre-configured for Testnet access |
| ​ | Constructs a Hedera client pre-configured for Mainnet access |
| File | Configures a client from a file |
| String | Contructs a network from a file |
| String | Configure a client from the given JSON string |
| Reader | Configure a client from the given JSON reader |
| Map<AccountId, String> | Replaces nodes in the network |
Java// From a pre-configured networkClient client = Client.forTestnet();​//Replace nodesMap<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 networkconst 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 |
| AccountId, PrivateKey |
| AccountId, PrivateKey, Function<byte[ ], byte [ ]> |
// Operator account ID and private key from string valueAccountId OPERATOR_ID = AccountId.fromString("0.0.96928");Ed25519PrivateKey OPERATOR_KEY = Ed25519PrivateKey.fromString("302e020100300506032b657004220420b9c3ebac81a72aafa5490cc78111643d016d311e60869436fbb91c7330796928");​// Pre-configured client for test network (testnet)Client client = Client.forTestnet()​//Set the operator with the operator ID and operator keyclient.setOperator(OPERATOR_ID, OPERATOR_KEY);
// Operator account ID and private key from string valueconst OPERATOR_ID = AccountId.fromString("0.0.96928");const OPERATOR_KEY = Ed25519PrivateKey.fromString("302e020100300506032b657004220420b9c3ebac81a72aafa5490cc78111643d016d311e60869436fbb91c7330796928");​// Pre-configured client for test network (testnet)const client = Client.forTestnet()​//Set the operator with the operator ID and operator keyclient.setOperator(OPERATOR_ID, OPERATOR_KEY);
// Operator account ID and private key from string valueoperatorAccountID, 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 keyclient.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 relevent dotenv module to your project files. The sample .env file may look something like this:
.envOPERATOR_ID= 0.0.9410OPERATOR_KEY= 302e020100300506032b65700422042012a4a4add3d885bd61d7ce5cff88c5ef2d510651add00a7f64cb90de3359bc5e
//Grab the account ID and private key of the operator account from the .env fileAccountId 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 keyclient.setOperator(OPERATOR_ID, OPERATOR_KEY);
//Grab the account ID and private key of the operator account from the .env fileconst 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 keyclient.setOperator(OPERATOR_ID, OPERATOR_KEY);
err := godotenv.Load(".env")if err != nil {panic(fmt.Errorf("Unable to load enviroment variables from demo.env file. Error:\n%v\n", err))}​//Get the operator ID and operator keyOPERATOR_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 setMaxTransactionFee()
and setMaxQueryPayment().
Method | Type | Description |
| Hbar | The maximum transaction fee the client is willing to pay. Default: 1 hbar |
| Hbar | The maximum query payment the client will pay. Default: 1 hbar |
| Map<String, AccountId> | Replace all nodes in this Client with a new set of nodes (e.g. for an Address Book update) |
| Duration | The period of time a transaction or query request will retry from a "busy" network response |
Java// For test network (testnet)Client client = Client.forTestnet()​//Set the operator and operator private keyclient.setOperator(OPERATOR_ID, OPERATOR_KEY);​//Set the max transaction fee the client is willing to pay to 2 hbarsclient.setMaxTransactionFee(new Hbar(2));​//v2.0.0
JavaScript// For test network (testnet)const client = Client.forTestnet()​//Set the operator and operator private keyclient.setOperator(OPERATOR_ID, OPERATOR_KEY);​//Set the max transaction fee the client is willing to pay to 2 hbarsclient.setMaxTransactionFee(new Hbar(2));​//v2.0.0
Go// For test network (testnet)client := hedera.ClientForTestnet()​//Set the operator and operator private keyclient.SetOperator(operatorAccountID, operatorKey)​//Set the max transaction fee the client is willing to pay to 2 hbarsclient.SetMaxTransactionFee(hedera.HbarFrom(2, hedera.HbarUnits.Hbar))​//v2.0.0
Method | Type | Description |
| Hbar/long | The maximum transaction fee the client is willing to pay. Default: 1 hbar |
| Hbar/long | The maximum query payment the client will pay. Default: 1 hbar |
JavaClient 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 keyclient.setOperator(OPERATOR_ID, OPERATOR_KEY);​//Set the max transaction fee the client is willing to pay to 2 hbarsclient.setMaxTransactionFee(new Hbar(2));​//v1.4.4
​