Questions tagged [web3j]
Lightweight Java and Android library for integration with Ethereum clients
289
questions
0
votes
1answer
8 views
Installing Web3 stuck on fetchMetadata: sill resolveWithNewModule http-https@1.0
I am trying to install web3 for ethereum but it keeps sticking on this fetchMetadata
0
votes
1answer
31 views
Not able to generate java wrapper class from solidity smart contract using truffle
I'm trying to generate java wrapper class of solidity smart contract using truffle but not getting wrapperclass.java file
Here is an command which i've used to generate abi/Json of that contract
...
0
votes
1answer
16 views
How estimate GAS from a contract call with Web3j
I'm trying to estimate gas cost of a contract call, i need to send a string to a contract, but i need to see if i overtook the GAS limit.
I'm trying like this:
Transaction t = Transaction....
1
vote
1answer
24 views
Unable to load smart contract using web3j on android
What I'my trying to do is to load already deployed smart contract and interact with it. The problem is that after my credentials are being created properly, the error is being catched but the message ...
0
votes
1answer
38 views
Listen to Ethereum transactions
I need to listen ethereum transactions for current count of addresses using web3j. I know that I can use subscribe to get transactions, but how can I add some filter to listen a certain number of ...
1
vote
0answers
28 views
Web3J - how to perform two identical transactions in a row?
I have a contract being an ERC-20 token. I want to perform two idendical transfers (sender, receiver and amounts are the same).
I am using the contract objects from Web3j:
MyToken token = MyToken....
0
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0answers
41 views
Send ERC-20 token using Web3j
What is the best way to get balance and send ERC-20 token using web3j?
1
vote
1answer
33 views
How to get events on android with infura?
I am developing an app on Android, but Web3j does not support events on infura ( Should I use Infura with Web3j for Event filter? ) .
What are the options, I did not find any alternative library?
0
votes
0answers
188 views
how to integrate USDT erc20 token to make transfer and check balanceof?
I want to integrate USDT token to make transfer and check balance of USDT in my java with the use of web3j, how can i accomplish this?
i able to create wallet and use of ethereum, but i dont know how ...
1
vote
0answers
46 views
How to achieve inheritance support using web3j wrapper?
I have two types of smart contracts. One parent contract to store the type and other child contracts which inherits the parent contract.
The problem is, I can't generate java wrapper class (...
0
votes
0answers
53 views
How to use web3j to check the balance of an ERC20 custom Token and transfer the token to another wallet?
I'm studying to create wallets using infura, web3j, and android studio.
I am using ropsten testnet.
I have been able to check the amount of ethereum in my wallet and send ethereum to another account.
...
0
votes
0answers
35 views
Generated code using web3j contains errors
This is the smart contract
pragma solidity ^0.5.0;
pragma experimental ABIEncoderV2;
import "./sharedLib.sol";
import "./clientSC.sol";
import "./projetSC.sol";
contract ...
0
votes
0answers
26 views
How to send Extra data with smart contact transaction on geth server which data I will get after mining?
I have created smart contract in solidity using Remix IDE. I am doing smart contract transaction using geth server and it is working fine.
But I want to send some keys (data) on geth server with ...
1
vote
2answers
168 views
How to create a RawTransaction for contract interaction Web3j
I want to sign a transaction that calls a smart contract function and send it to the Rinkeby network.
I found on Web3j documentation the RawTransaction class that supports the methods for the ...
0
votes
0answers
24 views
How does remix decode a contract response without the ABI?
Remix seems to be able to decode the output of a contract to a block of JSON without having the ABI (say I just specify the contract address). How is this achieved - I'm interested in doing something ...
0
votes
0answers
22 views
web3j - getter for array of addresses
I have a contract which has a field registry which is an array of addresses, Also have a getter for this field:
function getRegistry() view public returns (address[] memory){
return ...
0
votes
1answer
60 views
getWeb3ClientVersion() returns null
I'm trying to create an android Dapp by using the web3j library. I'm using connection to a local private Ethereum blockchain. When I'm trying to display the Client version it returns null.
This is the ...
1
vote
1answer
28 views
Using contract to create Child contracts (web3j Java wrapper)
I have a simple Parent contract that creates child contracts and stores their address.
contract Parent {
address[] public registry;
function createChild () public {
address newChild =...
0
votes
0answers
111 views
SocketTimeoutException timeout In Java Web3j
Im developing some test in a little project with Web3j. I have a little for that loop generating new accounts.
Doing single request works fine. The issue appear when I try to make more than X ...
0
votes
0answers
18 views
Geth node from private network freezes and Web3j fails with timeout
I have a private network, and something very weird happens when I try to start the mining via RPC: the node just simply freezes. I attached using geth.ipc and even when I tried to start the miner via ...
0
votes
0answers
20 views
JVM waits for some timeout every time when I load a Smart Contract using Web3j In Java
Initially I had a problem with the Web3j object, but after explicitly calling its shutdown method everything works fine (JVM quits immediately, so my application closes). The problem occurs when I ...
0
votes
0answers
129 views
Why does the error Invalid response received: 403;?
Develop a java project to connect to ethereum blockchain and until now no error has been presented, but now this error appeared:
org.web3j.protocol.exceptions.ClientConnectionException: Invalid
...
1
vote
0answers
50 views
Using web3j with infura returns null
I've used web3.js to handle my contracts, and it worked very well.
But web3j is pretty hard for me since the beginning.
I'm using android studio, infura, web3j.
Since I don't know very much about ...
0
votes
1answer
38 views
How do we communicate with contract functionality which is deployed in public test network using web3j [closed]
I would like to write a wepapp for security token contract which is deployed in public Ropsten Test Network using web3j. Need some idea.
Thanks in Advance
0
votes
1answer
146 views
How to use eth_newFilter to get pending incoming transactions to a contract?
I'm trying to get pending transactions to a certain contract using Infura.
Is it possible to do that using eth_newFilter? Since apparently these filters only "trigger" from contract events, does that ...
1
vote
0answers
50 views
Extra mining fees added in etherbase account
1st scenario -
I have set miner.setEtherbase(eth.accounts[1]) and gasPrize is 0.
1 coin Transaction -
And done transaction from 0th account to one random account. I expect 0 mining fees will add ...
1
vote
1answer
70 views
Can I send data (e.g. text) in a Transaction with Web3J?
I need to send a transaction from an account to another one via Web3J that includes not only the value field but also the data field (in particular, I need to send text). Is it possible?
0
votes
1answer
80 views
How to create a wallet file for existing account&
I found this way of creating a new ethereum account with web3j. But what if I want to create a wallet file for an already registered account? I need this because most of the web3j functions require a ...
1
vote
0answers
30 views
Trouble with personalUnlockAccount,web3j
I am creating android dapp for votings
I am trying to check if user's credentials are right,so i use object of PersonalUnlockAccount class and function accountUnlocked().So the problem is that when i ...
0
votes
1answer
61 views
org.web3j.protocol.exceptions.TransactionException: Transaction receipt was not generated after 600 seconds for transaction
I am sending a transaction through this code
public String transferEthByPk(String amount, String toAddress, String privateKey, Web3j web3j) {
BigDecimal value = new BigDecimal(amount);
...
0
votes
0answers
18 views
Java class generated with web3j has a “deploy” method wherein initialWeiValue, initialSupply have to be both specified. Isn't it the same amount?
Method in the java class generated by web3j is like this:
public static RemoteCall<Crowdfunding> deploy(Web3j web3j, Credentials credentials, BigInteger gasPrice, BigInteger gasLimit, ...
0
votes
0answers
15 views
Read contract value from Android
I have deployed successfully a smartcontract onto Rinkeby at the address : 0x69cfa9009Bf2c7a9945a4f8b381db21b26b662d7
It is a tutorial smartcontract that enables an election between 2 candidate.
I ...
0
votes
0answers
94 views
Get Array from a call in Web3j
I have a solidity function that returns an array.
I'm trying to read the values inside this array from web3j but it gives me stage results.
My solidity function
function getAllSubTokenByTokenID(...
0
votes
2answers
29 views
How to find out if a wallet (an address) contains a token from a contract using web3js?
Is this possible with and without knowing the private key of the wallet.
0
votes
0answers
42 views
How to set an array of struct in the function param
this is the function :
function setListObjects(ContractObject[] memory ContractObjects)public{
delete objects;
ContractObject memory newObject;
for (uint i = 0; i < ContractObjects....
0
votes
1answer
62 views
Transaction no confirmed and JUnit test assert fail
I have some JUnit test that assert some values returned from the blockchain deployed smart-contract. But the assert return me a error because the assertEqual call is done when the transaction has not ...
0
votes
0answers
134 views
Web3J Websocket Connection Closes
While using Web3j websocket connection faced connection closed issue. After some time the connection was established and served few requests abruptly the connection closes.
Request you to share the ...
1
vote
1answer
139 views
Quorum deploy with Web3j timeout
SCENARIO:
I have the following code:
final String hostUrl = this.deployerProperties.getProperty("quorum.host.url");
final String hostPort = this.deployerProperties.getProperty("quorum.host.port");
...
0
votes
1answer
50 views
Could someone explain to me the use of the FastRawTransactionManager class?
int pollingInterval = 3000;
FastRawTransactionManager fastRawTxMgr = new FastRawTransactionManager(web3j, credentials, new PollingTransactionReceiptProcessor(web3j, pollingInterval, 40));
From what I ...
0
votes
0answers
199 views
Transaction receipt was not generated after 600 seconds for transaction:
I am sending a transaction through this code:
txhash = careercertificate
.createCertificate(id, fecha, nombre, rutalumno, instituto, rutinstituto, titulo, totalhash, ...
1
vote
1answer
48 views
Sending private key to server side
I am trying to build new Dapp application for our startup by using web3j , I am facing an issue with signing the transaction from server side , because i need to know the private key for the client (...
1
vote
2answers
315 views
Empty value (0x) returned from contract web3j
I'm trying to deploy a very simple contract on Windows 10, using Web3j 4.2.0. I've created an account using Mist. I've set up one local ethereum node (using geth) on my machine and I'm able to deploy ...
0
votes
1answer
171 views
Load smart contracts in Java application without having the java wrapper class for Web3j (only the address of the contract)
I use web3j to interact with my local Ethereum node (created with geth), and I was wondering how should I handle smart contracts created at runtime.
I know that in order to deploy a smart contract ...
0
votes
0answers
27 views
Send ether from one wallet to another
I have two metamask accounts and what I want to do is send ether between those accounts. For the interaction between those accounts, use infura, I give the address of both accounts but in the end the ...
2
votes
2answers
346 views
invalid opcode “0x1c” during smart contract method execution
I have written a smart contract to test event from java project using web3j
I have prepared the web3j wrapper java class using solc compiler version
"0.5.7+commit.6da8b019.Linux.g++"
I am using a ...
0
votes
0answers
56 views
Invalid OPCode on passing address parameter through Java wrapper on smart contract using Ganache
I have been facing this issue for some time and I realized there must be a problem with Ganache or maybe someone has any idea why it doesn't work.
I have created a very simple contract as below, it ...
1
vote
2answers
200 views
Offline transaction signing with web3j?
I'd like to generate and sign a transaction offline and then send that transaction with a different account. I've found a few web3js sources and I've read the web3 documentation, but I haven't found ...
0
votes
2answers
231 views
What's problem about “gas required exceeds allowance or always failing transaction”
I translate smart contract into Java with solc and web3j, but I meet the probelm "gas required exceeds allowance or always failing transaction".
This is my smart contract.
It is work when I use ...
1
vote
1answer
33 views
Is it worthwhile to store my supply chain product data on the blockchain using a smart contract? [closed]
I'm currently developing an android app that uses the Web3j framework (Java) to interact with my private Ethereum blockchain (running on Ganache). The app is a supply chain tool that will let users ...
0
votes
2answers
131 views
Unable to make a transaction with Data using Java api ethSendRawTransaction
I am trying to make a transaction between two different accounts using Java. It works perfectly fine as long as I am not using "Data" parameter.
My intent is not to call a smart contract but to make ...
