Creating and Managing Accounts

The Java SDK provides comprehensive support for various account types and key management schemes. You can create single-key accounts, multi-signature accounts, and derive accounts from hierarchical deterministic (HD) wallets.

Single-Key Accounts (Ed25519)

The most common way to create an account is using the Ed25519 signature scheme.

Generate a New Account

import com.aptoslabs.japtos.account.Ed25519Account;

// Generate a new Ed25519 account
Ed25519Account account = Ed25519Account.generate();

// Access account properties
System.out.println("Address: " + account.getAccountAddress());
System.out.println("Public Key: " + account.getPublicKey());
System.out.println("Private Key: " + account.getPrivateKey());

Create Account from Private Key

If you already have a private key, you can create an account from it:

import com.aptoslabs.japtos.core.crypto.Ed25519PrivateKey;

// Create account from existing private key
Ed25519PrivateKey privateKey = Ed25519PrivateKey.fromHex("your_private_key_hex");
Ed25519Account account = new Ed25519Account(privateKey, null);

Funding Accounts

Once you have generated credentials, you must fund the account for the network to recognize it.

On devnet or localnet, you can use the faucet:

import com.aptoslabs.japtos.client.AptosClient;
import com.aptoslabs.japtos.api.AptosConfig;

AptosConfig config = AptosConfig.builder()
    .network(AptosConfig.Network.DEVNET)
    .build();
AptosClient client = new AptosClient(config);

// Fund account with 1 APT (100_000_000 octas)
client.fundAccount(account.getAccountAddress(), 100_000_000);

警告

Faucet funding is only available on Devnet and Localnet. For Testnet and Mainnet, you’ll need to acquire APT through other means.

Hierarchical Deterministic (HD) Wallets

The Java SDK supports BIP39 mnemonic phrases and BIP44 derivation paths for creating deterministic wallets.

Derive Account from Mnemonic

import com.aptoslabs.japtos.account.Account;

// Standard BIP39 mnemonic phrase
String mnemonic = "abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about";

// BIP44 derivation path for Aptos (coin type: 637)
String derivationPath = "m/44'/637'/0'/0'/0'";

// Derive account
Ed25519Account account = Account.fromDerivationPath(derivationPath, mnemonic);
System.out.println("Derived address: " + account.getAccountAddress());

Derive Multiple Accounts

You can derive multiple accounts from the same mnemonic by changing the account index:

String mnemonic = "your mnemonic phrase here";

// First account
Ed25519Account account0 = Account.fromDerivationPath(
    "m/44'/637'/0'/0'/0'",
    mnemonic
);

// Second account
Ed25519Account account1 = Account.fromDerivationPath(
    "m/44'/637'/1'/0'/0'",
    mnemonic
);

// Third account
Ed25519Account account2 = Account.fromDerivationPath(
    "m/44'/637'/2'/0'/0'",
    mnemonic
);

Convert Entropy to Mnemonic

You can generate a mnemonic phrase from entropy (such as a UUID):

import com.aptoslabs.japtos.utils.Bip39Utils;

// Convert UUID/entropy to mnemonic phrase
String entropy = "9b4c9e83-a06e-4704-bc5f-b6a55d0dbb89";
String mnemonic = Bip39Utils.entropyToMnemonic(entropy);

System.out.println("Mnemonic: " + mnemonic);
// Output: "defense balance boat index fatal book remain champion cushion city escape huge"

Multi-Signature Accounts

Multi-signature accounts allow multiple parties to control an account. Transactions require a minimum threshold of signatures to be valid.

Create a 1-of-2 Multi-Signature Account

import com.aptoslabs.japtos.account.MultiEd25519Account;
import com.aptoslabs.japtos.core.crypto.Ed25519PrivateKey;
import java.util.Arrays;
import java.util.List;

// Create two individual accounts
Ed25519Account account1 = Ed25519Account.generate();
Ed25519Account account2 = Ed25519Account.generate();

// Create multi-signature account with 1-of-2 threshold
List<Ed25519PrivateKey> privateKeys = Arrays.asList(
    account1.getPrivateKey(),
    account2.getPrivateKey()
);

MultiEd25519Account multiAccount = MultiEd25519Account.fromPrivateKeys(
    privateKeys,
    1  // threshold: only 1 signature required
);

System.out.println("Multi-sig address: " + multiAccount.getAccountAddress());

Create a 2-of-3 Multi-Signature Account

For higher security, you can require multiple signatures:

// Create three individual accounts
Ed25519Account account1 = Ed25519Account.generate();
Ed25519Account account2 = Ed25519Account.generate();
Ed25519Account account3 = Ed25519Account.generate();

// Create multi-signature account with 2-of-3 threshold
List<Ed25519PrivateKey> privateKeys = Arrays.asList(
    account1.getPrivateKey(),
    account2.getPrivateKey(),
    account3.getPrivateKey()
);

MultiEd25519Account multiAccount = MultiEd25519Account.fromPrivateKeys(
    privateKeys,
    2  // threshold: 2 signatures required
);

Multi-Signature with Specific Signers

You can create a multi-signature account where only specific keys can sign:

import com.aptoslabs.japtos.core.crypto.Ed25519PublicKey;

// Create accounts
Ed25519Account account1 = Ed25519Account.generate();
Ed25519Account account2 = Ed25519Account.generate();
Ed25519Account account3 = Ed25519Account.generate();

// Only account1 and account2 can sign
List<Account> signers = Arrays.asList(account1, account2);

// But all three public keys are part of the multi-sig
List<Ed25519PublicKey> publicKeys = Arrays.asList(
    account1.getPublicKey(),
    account2.getPublicKey(),
    account3.getPublicKey()
);

// Create multi-sig account (2-of-3, but only first 2 can actually sign)
MultiEd25519Account multiAccount = MultiEd25519Account.from(
    signers,
    publicKeys,
    2  // threshold
);

Signing Messages

All account types support message signing and verification:

// Sign a message
String message = "Hello, Aptos!";
byte[] messageBytes = message.getBytes();
Signature signature = account.sign(messageBytes);

// Verify signature
boolean isValid = account.verifySignature(messageBytes, signature);
System.out.println("Signature valid: " + isValid);

Account Address Formats

Aptos account addresses are 32-byte values typically represented as hexadecimal strings:

import com.aptoslabs.japtos.types.AccountAddress;

// Create from hex string (with or without 0x prefix)
AccountAddress address1 = AccountAddress.fromHex("0x1");
AccountAddress address2 = AccountAddress.fromHex("0000000000000000000000000000000000000000000000000000000000000001");

// Both represent the same address (0x1)
System.out.println(address1.toString()); // 0x1
System.out.println(address2.toString()); // 0x1

Best Practices

1. Never expose private keys: Store private keys securely and never commit them to version control
2. Use HD wallets for multiple accounts: Derive multiple accounts from a single mnemonic for easier backup
3. Secure mnemonic phrases: Treat mnemonic phrases like passwords - they can recover all derived accounts
4. Test on devnet first: Always test your account management code on devnet before using it on mainnet
5. Multi-sig for high-value accounts: Use multi-signature accounts for enhanced security on important accounts

Example: Complete Account Workflow

Here’s a complete example showing account creation, funding, and balance checking:

import com.aptoslabs.japtos.account.Ed25519Account;
import com.aptoslabs.japtos.api.AptosConfig;
import com.aptoslabs.japtos.client.AptosClient;
import com.aptoslabs.japtos.types.AccountAddress;
import com.google.gson.JsonObject;

public class AccountWorkflow {
    public static void main(String[] args) throws Exception {
        // Setup client
        AptosConfig config = AptosConfig.builder()
            .network(AptosConfig.Network.DEVNET)
            .build();
        AptosClient client = new AptosClient(config);

        // Generate account
        Ed25519Account account = Ed25519Account.generate();
        System.out.println("Generated address: " + account.getAccountAddress());

        // Fund account
        client.fundAccount(account.getAccountAddress(), 100_000_000);
        System.out.println("Account funded!");

        // Check balance
        String resourceType = "0x1::coin::CoinStore<0x1::aptos_coin::AptosCoin>";
        JsonObject resource = client.getAccountResource(
            account.getAccountAddress(),
            resourceType
        );
        long balance = resource.getAsJsonObject("coin")
                              .get("value")
                              .getAsLong();

        System.out.println("Balance: " + balance + " octas");
        System.out.println("Balance: " + (balance / 100_000_000.0) + " APT");
    }
}

Related Documentation

• Building Transactions
• Java SDK Examples
• BIP39 Specification
• BIP44 Specification