Web3j web3j = Web3j.build(new HttpService("http://localhost:8545")); Credentials credentials = WalletUtils.loadCredentials("password", "/path/to/keystore"); TransactionReceipt receipt = Transfer.sendFunds(web3j, credentials, "0x<recipient_address>", BigDecimal.valueOf(1.0), Convert.Unit.ETHER).send(); HelloWorld contract = HelloWorld.load("<contract_address>", web3j, credentials, gasPrice, gasLimit); TransactionReceipt receipt = contract.greet().send(); <dependency> <groupId>org.web3j</groupId> <artifactId>web3j-core</artifactId> <version>5.0.0</version> </dependency> Web3j web3j = Web3j.build(new HttpService("http://localhost:8545"));