How can I get the TxReceipt of a transaction with web3j?

Question

How can I get the status of a transaction through the TxHash with web3j.

I tried it like this:

public int getEstado(String trx) {
    try {
        JSONObject json = readJsonFromUrl("https://api.infura.io/v1/jsonrpc/rinkeby/eth_getTransactionReceipt?params=[\"" + trx + "\"]");

        if (json.toString().contains("error")) {
            return -4;
        }

        String result = Parser.getMessageByKey(json.toString(), "status");
        int estado = Integer.decode(result);
        json = null;
        result = null;
        return estado;

    } catch (Exception ex) {
        return -4;
    }
}

In the end this did not work, so I wanted to know if you can guide me in another way to get the status of txHash.

Answer 1

There's the Transactions page in the Web3j docs that mentions transaction receipts a few times, and I browsed through some of the autocompletes in IntelliJ. It looks like you can do the following, provided you have the transaction hash:

Optional<TransactionReceipt> transactionReceipt = 
    web3j.ethGetTransactionReceipt(txHash).send().getTransactionReceipt();

Then you can check whether the optional holds a value and retrieve the transaction receipt. I haven't tested this, but I don't see why it shouldn't work. Let me know if it helps.

Answer 2

one question. How do you handle the case when the value of the optional is not present. Do you do a Thread.sleep in a loop and check if the value is present with the .isPresent method? this does not feel as a correct way to handle async code.

Pseudo code:

for(;;) {
  if (transactionReceipt.getTransactionReceipt.isPresent()) {
    return transactionReceipt.get().getContractAddress();
  } else {
    Thread.sleep(3)
  }
}