uRaiden balance proof with web3j

uRaiden.java

    private void pkDisplay(Web3j web3j) throws Exception {
        String privateKey1 = "1587352d059682a7ebb86e4aecc86f73cf418d33f9af4178ce344a3dd41a813b";
        Credentials credentials = Credentials.create(privateKey1);
        log.info("Address: " + credentials.getAddress());

        List<String> labels = Arrays.asList(
                "string message_id",
                "address receiver",
                "uint32 block_created",
                "uint192 balance",
                "address contract"
        );

        ByteBuffer buffer = ByteBuffer.allocate(labels.stream().mapToInt(a -> a.getBytes().length).sum());
        for (String a : labels) {
            buffer.put(a.getBytes());
        }
        byte[] array = buffer.array();

        Tester contract = Tester.deploy(
                web3j, credentials,
                ManagedTransaction.GAS_PRICE, Contract.GAS_LIMIT).send();

        String contractAddress = contract.getContractAddress();

        List<byte[]> values = Arrays.asList(
                "Sender balance proof signature".getBytes(),
                Numeric.hexStringToByteArray(credentials.getAddress()),
                Numeric.toBytesPadded(BigInteger.valueOf(400000), 4),
                Numeric.toBytesPadded(BigInteger.valueOf(100), 24),
                Numeric.hexStringToByteArray(contractAddress)
        );

        ByteBuffer bufferValues = ByteBuffer.allocate(values.stream().mapToInt(a -> a.length).sum());
        for (byte[] a : values) {
            bufferValues.put(a);
        }
        byte[] arrayValues = bufferValues.array();

        ByteBuffer byteArrayBuffer = ByteBuffer.allocate(64);
        byteArrayBuffer.put(Hash.sha3(array));
        byteArrayBuffer.put(Hash.sha3(arrayValues));
        byte[] arrayValuesBuffer = byteArrayBuffer.array();

        Sign.SignatureData signature = Sign.signMessage(arrayValuesBuffer, credentials.getEcKeyPair());

        ByteBuffer sigBuffer = ByteBuffer.allocate(signature.getR().length + signature.getS().length + 1);
        sigBuffer.put(signature.getR());
        sigBuffer.put(signature.getS());
        sigBuffer.put(signature.getV());

        log.info("Smart contract deployed to address " + contractAddress);
        log.info("View contract at https://rinkeby.etherscan.io/address/" + contractAddress);
        log.info("Value stored in remote smart contract: " + contract.extractBalanceProofSignature(
                credentials.getAddress(),
                BigInteger.valueOf(400000),
                BigInteger.valueOf(100), sigBuffer.array()).send());
    }

Please use the private key with care, it has some ETH on Rinkeby. For creating the balance proof, ETH is not necessary, but for the deployment of the uRaiden smart contract.