Questions tagged [ethereumj]

For questions regarding the installation or use of EthereumJ, a Java library that implements the Ethereum protocol.

Filter by
Sorted by
Tagged with
4
votes
1answer
145 views

How to work with inherited contracts in EthereumJ?

In EthereumJ, I have two contracts i deployed them individually,first one was deployed but for the second i got error as in that i was calling function of first one and example i have second is first ,...
2
votes
1answer
55 views

Dev install fails for Python 3.8 when installing py-evm dependencies

When following this guide in the py-evm docs, I get this verbose error when installing dependencies. It appears to be related to mypy and typed-ast, but I don't know enough about these to be able to ...
0
votes
1answer
16 views

What happens if the tokenURI api serves a different metadata?

The way to reference the actual payload of the NFT is a centralized endpoint. When I create the NFT I might provision an API with an endpoint that serves a particular piece of data. What's to stop me (...
17
votes
3answers
18k views

'authentication needed: password or unlock' Error when trying to call smart contract method via web3

I am trying to call the smart contract method (deployed on remote ethereum account) from my nodejs DAPP, and getting the following error- Error: authentication needed: password or unlock at ...
0
votes
2answers
231 views

EthereumJ connect to private node

I need to connect to private ethereum node with using ethereumj without ethereum.conf file. I need configure connect from code using Spring Framework.
2
votes
1answer
298 views

EthereumJ: Private Network: How to I set my sender account?

I'm currently using EthereumJ and I'm trying out a use case to send an amount to a specific account in my own private chain. But I'm getting this error: Not enough cash: Require: 14000000000000001, ...
0
votes
1answer
379 views

how to connect to a private ethereum testnet with blockcypher

our project uses blockcypher to create eth wallet which can transfer eth now.Blockcypher supports ETH main network and its own testnet. Is there any way to connect the blockcypher node to a custom ...
16
votes
3answers
2k views

How to get values returned by non constant transaction functions?

As per my understanding when I invoke a constant function without a transaction in a contract and if the function returns some result I am able to get it in EthereumJ or Go-Ethereum, But when a ...
1
vote
1answer
429 views

Correct way to calculate Gas Price and Gas Limit using offline mode in ethereumj

Please help me to understand the correct way to compute Gas Price and Gas Limit using offline mode in ethereumj. I have been using EtherScan's API eth_gasPrice and eth_estimateGas as of now. Just ...
1
vote
1answer
194 views

How to resolve this error in solidity “The constructor should be payable if you send value.”?

In this solidity code the finalizeRequest() is giving a run-time error. Here is the error : Campaign.finalizeRequest(uint256) 0x692...77b3a transact to Campaign.finalizeRequest errored: VM error: ...
0
votes
1answer
67 views

Transfer not working on buy swaps with ERC20

I am trying to send a percentage of ethereum to my marketing wallet when someone buys or sells my token via uniswap. It seems to work on sells but not on buys... why is that? i get nothing transferred ...
0
votes
1answer
217 views

Truffle Migrate

What happens when there is a minor change in the smart contract and I run truffle migrate command. Example: //before contract test{ function display() public returns (string){ return "...
1
vote
1answer
42 views

How to decide SPDX license for a smart contract? [closed]

I am not sure how to decide which spdx licence will go with my smart contract. Can anyone help like how decide which spdx licence will be use in a contract.
0
votes
1answer
83 views

Having a problem compiling a ERC20 token smart contract - Code inside

Basically i'm using a cut and paste erc20 token code from this site: https://hashnode.com/post/how-to-build-your-own-ethereum-based-erc20-token-and-launch-an-ico-in-next-20-minutes-...
1
vote
1answer
146 views

LoadCredentials function returns file not found exception

I am using the following code to deploy my contract: @RequestMapping("/") public String index() throws Exception { Web3j web3j = Web3j.build(new HttpService("https://rinkeby.infura.io/v3/...
9
votes
2answers
700 views

Error: "message":"function \"Ballot\" arguments must include \"proposalNames\""}

I am trying below code to write Voting Contract referring to Solidity documentation pdf. Code compiles without error but I am getting below error while deploying. writing Ballot to app\meta\Ballot\...
0
votes
0answers
8 views

Is it possible to do privacy preserving token metadata sharing between Ethereum and a TEE

Is it possible to do a privacy preserving ERC 721 / ERC 1155 token metatadata transfer between Ethereum Layer 1 Smart Contract based Token Vault and a Trusted Execution Environment like Intel SGX or ...
0
votes
1answer
227 views

Im getting the following error: ParserError: Expected primary expression. struct ManagingOrder.Parking memory new_Parking = Parking({

Im using blockchain technology for the first time, for a college project. Im trying to run a smart contract from Github. After debugging the errors shown while compiling the smart contract (in ...
1
vote
4answers
2k views

how much does using ethereum services cost

Lets say im creating my own cryptocurrency and my own blockchain on ethereum, what would be the basic costs for setting all this up if i am developing on Ethereum
0
votes
0answers
17 views

Cannot import Aave in remix

I tried to load aave in remix by following the below code pragma solidity ^0.6.6; import "https://github.com/aave/flashloan-box/blob/Remix/contracts/aave/FlashLoanReceiverBase.sol"; import &...
2
votes
1answer
267 views

Use uint40 for time in Solidity?

My question is: Should I use uint40 for time in Solidity? All the examples I've seen use uint256 for time, however, I think it's too wasteful -- while using uint32 is maybe a little aggressive due to ...
0
votes
0answers
11 views

Why my hash value for separate files is not being rendered?(Ethereum Solidity)

I'm trying to store my files in IPFS and get the hash value and store them in the smart contract.I want to render my hash value in the frontend page. But in the below code the hash value of first ...
0
votes
1answer
464 views

Query Ethereum Blockchain for functions return value of a Specified Smart Contract

I want to get smart contract functions return value sent by a specified smart contract within a range of blocks. I found a [manual] working method to achieve this: async function getTxsByAccount(...
1
vote
1answer
250 views

How to make user sign up and login on my decentralized application?(on production it should work without metamask)

Assuming that user who is going to signup is not having any ethereum account so how can I generate a public, private key and address for ethereum and make use of it to make further transactions. Users ...
2
votes
1answer
160 views

Is IPFS mandatory for NFT

Is it mandatory to use IPFS for file storage and use its hash in metadata for NFT, What if file is stored on s3 and we save its sha256 or md5 in metadata? Hash will be same until file content is ditto,...
0
votes
0answers
53 views

web3 transaction value always 0

Can anyone explain to me, why the transaction object I receive via web3 always has a value of 0? When I open up the transactionhash in etherscan, it shows under the to field which is named "...
0
votes
0answers
14 views

Remix Deployment

I'm deploying an erc20 token on the ethereum mainnet and so far every time I attempt a deploy the console displays "Creation of DappToken pending..." and an etherscan link that leads to &...
0
votes
0answers
13 views

Block timestamp or block number as short time check [duplicate]

Which one is better to check short period of time change 60seconds block.timestamp or block.number?
0
votes
2answers
46 views

Internal transaction [duplicate]

So, I was using Bitbuy to buy and send eth to the wallet of my friend. I dont know how but that transaction finish as internal and it doesnt appear on friends wallet. Does anyone know who needs to do ...
1
vote
1answer
765 views

How do I call the burnFrom() function once my contract is deployed?

I'm using the Openzeppelin library in my contract where MyToken is StandardBurnableToken. Once I deploy that and I want to burn a set amount of the initial supply how do I call the function? I don't ...
1
vote
1answer
49 views

Make Hyperledger Besu sync faster during DOS blocks

I am attempting to sync a full node using Hyperledger Besu and it has slowed down considerably when hitting about block 2,300,000. Geth and Parity can be made faster as this link details to sync these ...
1
vote
2answers
452 views

Storing data on IPFS using KMS and ethereum

I am trying to build a blockchain on ethereum but keeping the data related to blocks in some distributed file storage system like IPFS or Storj and storing the hash of data in blocks. But we need our ...
0
votes
0answers
30 views

I want to fork Ethereum with my own implementation. Like changing name or block size or something like this [duplicate]

I'm such a noob or may be this is a noob type question i just want to fork Ethereum in go(maybe in another language) with my own implementation. Anyone can guide me about that?? Is there any relevant ...
2
votes
3answers
2k views

How to use Solidity solc to compile A.sol that imports B.sol file?

I know how to install solc via "npm install --save solc" then use solc.compile to compile one sol file. But now I've got A.sol file that imports B.sol file, and when I run node compile.js, no error in ...
-1
votes
1answer
180 views

How and when should I use a Ethereum smart contract in document verification process?

First, a student applies for a certificate in his/her University . The University creates his degree certificate . Now , how do I write a smart contract in Solidity so that anyone in blockchain can ...
11
votes
5answers
13k views

How can I browse mempool in Ethereum?

How can I browse mempool in Ethereum? Is it possible from EthereumJ or on some websites?
0
votes
0answers
162 views

How to solve Transaction has been reverted by the EVM , In need of a solution based on my code?

I have been using ropsten with infura. SMART CONTRACT contract Don { struct Details { uint id; string name; string dob; ...
0
votes
2answers
31 views

Struct Properties Cannot Be Identified

I have been learning Solidity and I have run into a scoping issue with the structs. I thought by default, all properties of a struct are put into storage. When I try to add the battles variable as an ...
0
votes
2answers
51 views

Calling smart contract functions and submitting transacions in BACK-END in high level

I have read some references to create ethereum transactions by a BACK-END server, all in low level, for example, requiring that I control the nonce by myself. Are there safe ways to avoid this control ...
1
vote
4answers
3k views

How to access ethereum smart contract(already deployed) in a Java application via its address using web3j?

I have an existing Smart contract address,abi,binary code. I need to access it from a Java application.Is it possible to do this without creating a java wrapper class?
0
votes
1answer
31 views

Why the need for different tokens?

So, ERC20 tokens are bought depositing equivalent Price = amount to be bought*price of tokens) in eth to the smart contract eth address. So lets talk about BAT ERC20 token: If I am verified BAT ...
0
votes
1answer
10 views

How many parallel read/write request single contract can handle each second

I need this reply for a large user base prospective, where each second too many request going to that particular contract , so the question is what is write per second limit and what is read per ...
2
votes
1answer
644 views

how to call "selfdestruct" if not written in contract, as documentation says its possible

as mentioned in documentation "Even if a contract’s code does not contain a call to selfdestruct, it can still perform that operation using delegatecall or callcode." so my question is how ...
1
vote
1answer
320 views

Smart Contract Application in ASP>NET [closed]

I just have started to learn Smart Contract. I have to design front end in ASP.NET. Can I call Contract from it?
1
vote
2answers
2k views

Could not find artifacts for ./Election from any sources

I tried solutions provided in ethereum stack, but nothing worked for me. My smart contract file: pragma solidity ^0.4.15; contract Election { string public candidate; function Eletion () ...
2
votes
2answers
955 views

How to get the same SHA3 hash as soliditySHA3(ethereumjs-abi) returns using web3.sha3 in js?

I'm trying to hash a message as shown here: function constructPaymentMessage(contractAddress, amount) { return ethereumjs.ABI.soliditySHA3( ["address", "uint256"], [contractAddress, amount],...
0
votes
0answers
116 views

Just not able to install Web3 through powershell

After reading a lot of articles about how to install Web3j in windows. I also tried following this article : https://kauri.io/generate-a-java-wrapper-from-your-smart-contract/...
0
votes
0answers
572 views

TypeError: Operator != not compatible with types string storage ref and int_const 0

Im using blockchain technology for the first time, for a college project. Im trying to run a smart contract from Github (in Powershell windows 10). Im unable to compile the contract due the following ...
1
vote
1answer
36 views

Value of emitted events in App.js

Actually in my App.js I have called my contract function like this: [ this.state.swapcontract.methods.sendFunds(address).send({ from: this.state.account , value:amount}) ] The function is called ...
0
votes
1answer
88 views

Can we use secp256r1 to generate valid Ethereum address instead of secp256k1?

We interact with HSM via Graphene to generate EC public/private key for Ethereum blockchain, many tutorials say secp256k1 to generate valid Eth address, however the Graphene supports only secp256r1