via Bitcoinj , i am trying to create hot wallet as front used to get balance , create unsigned transaction (corresponding , i have cold wallet forever be offline used to sign transaction only)

My question is how to create/startup my hot wallet , temporarily i use wallet.fromWatchingKeyB58 to retrieve , but watch-only wallet can not create unsigned transaction with inputs , and it's spendable balance always is zero .

whether my concept or method to do it is wrong ?

belowing is func to create unsigned transaction , retrieved by watching key

public String createUnsignedTx(String userId ,String fromAddress ,String externalAddress ,
        String amount ,@Nullable String feePerKB) throws InsufficientMoneyException {

    try {

        SendRequest request = SendRequest.
                to(Address.fromBase58(BtcUtil.getNetwork(), externalAddress), Coin.valueOf(Long.valueOf(amount)) );

        request.signInputs = false;


        request.tx.getInputs();

        request.missingSigsMode = MissingSigsMode.USE_DUMMY_SIG;
        wallet.completeTx(request);
        logger.info("-----------generated unsign tx start ----------");
        logger.info(request.tx.toString());
        logger.info("-----------generated unsign tx end -----------");
        File file = new File(exportUnsignedPath+"btc."+request.tx.getHashAsString()+".txn.unsign");
        FileUtils.writeByteArrayToFile(file, request.tx.bitcoinSerialize());

    } catch (Exception e) {
        logger.error(e.getMessage(),e);
    }
    return "created";