Create account with web3j

Question

Im trying to create a account using the web3j library. But i can´t find the method that create accounts. My idea is to make this judgment but not in the Geth console, but yes in the Java application using web3j:

geth account new

Any idea?

Im new in ethereum and till the moment im not generating wallet because im not using smart contracts. Mi idea is just create accounts with de Java application and make simple transacion of eth betwen them in a private chain.

Thank you

Answer 1

Using Web3j (3.4.0), this can be achieved in two steps:

1. Generate a key-pair Keys.createEcKeyPair()
2. Create the wallet Wallet.createStandard(seed, keyPair)

Example:

public static void main(String[] args) {

    try {
        String password = "secr3t";
        ECKeyPair keyPair = Keys.createEcKeyPair();
        WalletFile wallet = Wallet.createStandard(password, keyPair);

        System.out.println("Priate key: " + keyPair.getPrivateKey().toString(16));
        System.out.println("Account: " + wallet.getAddress());

    } catch(Exception e) {
        System.err.println("Error: " + e.getMessage());
    }

}

---

EDIT: create a wallet file

String fileName = WalletUtils.generateNewWalletFile(
        "secr3t",
        new File("/path/to/destination"));

Answer 2

I did this:

public class MainActivity extends AppCompatActivity {
    private WalletFile wallet;
    private String password = "PASSWORD";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        setupBouncyCastle();


        try {
            wallet = createWallet();
        } catch (Exception e) {
            System.out.println("BIG RIP");
        }
    }


    public WalletFile createWallet() throws Exception {
        ECKeyPair keyPair = Keys.createEcKeyPair();
        return Wallet.createLight(password, keyPair);

    }


    private void setupBouncyCastle() {
        final Provider provider = Security.getProvider(BouncyCastleProvider.PROVIDER_NAME);
        if (provider == null) {
            // Web3j will set up the provider lazily when it's first used.
            return;
        }
        if (provider.getClass().equals(BouncyCastleProvider.class)) {
            // BC with same package name, shouldn't happen in real life.
            return;
        }
        // Android registers its own BC provider. As it might be outdated and might not include
        // all needed ciphers, we substitute it with a known BC bundled in the app.
        // Android's BC has its package rewritten to "com.android.org.bouncycastle" and because
        // of that it's possible to have another BC implementation loaded in VM.
        Security.removeProvider(BouncyCastleProvider.PROVIDER_NAME);
        Security.insertProviderAt(new BouncyCastleProvider(), 1);
    }
}

For some reason, creating a wallet with path kept throwing errors. Part of my code was copied from: https://github.com/serso/web3a/blob/4dda74db948f8cbd9a79ba4b9ab456316ea52c4d/app/src/main/java/org/solovyev/android/web3a/App.java#L47, as newer versions of web3j throw errors when creating a ECKeyPair.