Build your Hedera client
1. Configure your Hedera network
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.
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
2. Define the operator account ID and private key
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.
Client.<network>.setOperator(<accountId, privateKey>)
AccountId, PrivateKey
Client.<network>.setOperatorWith(<accountId, privateKey, transactionSigner>)
AccountId, PrivateKey, Function<byte[ ], byte [ ]>
From an account ID and private key
From a .env file
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:
3. Additional client modifications
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().
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
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