opt, err := nats.NkeyOptionFromSeed("seed.txt")
if err != nil {
	log.Fatal(err)
}
nc, err := nats.Connect("127.0.0.1", opt)
if err != nil {
	log.Fatal(err)
}
defer nc.Close()

// Do something with the connection

NKey theNKey = NKey.createUser(null); // really should load from somewhere
Options options = new Options.Builder().
            server("nats://localhost:4222").
            authHandler(new AuthHandler(){
                public char[] getID() {
                    try {
                        return theNKey.getPublicKey();
                    } catch (GeneralSecurityException|IOException|NullPointerException ex) {
                        return null;
                    }
                }

                public byte[] sign(byte[] nonce) {
                    try {
                        return theNKey.sign(nonce);
                    } catch (GeneralSecurityException|IOException|NullPointerException ex) {
                        return null;
                    }
                }

                public char[] getJWT() {
                    return null;
                }
            }).
            build();
Connection nc = Nats.connect(options);

// Do something with the connection

nc.close();

// seed should be stored in a file and treated like a secret
const seed = 'SUAEL6GG2L2HIF7DUGZJGMRUFKXELGGYFMHF76UO2AYBG3K4YLWR3FKC2Q';

let nc = NATS.connect({
    url: server.nats,
    nkey: 'UD6OU4D3CIOGIDZVL4ANXU3NWXOW5DCDE2YPZDBHPBXCVKHSODUA4FKI',
    sigCB: function (nonce) {
        const sk = nkeys.fromSeed(Buffer.from(seed));
        return sk.sign(nonce);
    }
});

nc = NATS()

async def error_cb(e):
    print("Error:", e)

await nc.connect("nats://localhost:4222",
                 nkeys_seed="./path/to/nkeys/user.nk",
                 error_cb=error_cb,
                 )

# Do something with the connection

await nc.close()

// seed should be stored in a file and treated like a secret
const seed = 'SUAEL6GG2L2HIF7DUGZJGMRUFKXELGGYFMHF76UO2AYBG3K4YLWR3FKC2Q';

let nc = await connect({
    url: server.nats,
    nkey: 'UD6OU4D3CIOGIDZVL4ANXU3NWXOW5DCDE2YPZDBHPBXCVKHSODUA4FKI',
    nonceSigner: function (nonce) {
        const sk = fromSeed(Buffer.from(seed));
        return sk.sign(Buffer.from(nonce));
    }
});