create offline ethereum wallet in android

Question

How to create an Ethereum wallet (Keystore JSON file) in android using org.web3j:core:3.3.1-android (web3j library). Please guide me to create one.

Answer 1

Using https://github.com/web3j/web3j you can create JSON wallet file in your android external directory.

Android code to create a wallet JSON file in Downloads directory.

        public class Wallet {

// Create new wallet
public String createWallet() throws Exception {
    String path = Environment.getExternalStoragePublicDirectory(DIRECTORY_DOWNLOADS).getPath();
    String fileName = WalletUtils.generateLightNewWalletFile("password", new File(path));
    return path + fileName;
}

/* Load the new wallet file once it is created
*  Replace the File path with newly created wallet file path 
*/
public Credentials loadCredentials(String password) throws Exception {
    Credentials credentials = WalletUtils.loadCredentials(
            password,
            "/storage/emulated/0/Download/UTC--2018-03-16T19-05-15.125--833e56c5df2a654372a252658006af4d3158e9f3.json");
    Log.i("Loading credentials", "Credentials loaded");
    return credentials;
    }
}

Check https://github.com/subhodi/android-web3-lightwallet repo for creating a wallet, loading wallet, sending raw transaction, Deploy, write, query smart contract.