Reputation: 396
I'm tinkering with web3j and most of the things that I want to do succeed, however I seem to not be able to listen to events.
I've extended the ballot.sol contract you get with remix by adding an event VoteEnded, which is fired when a call is made to winningProposal and that works in the Remix JavaScript VM.
...
event VoteEnded();
...
function winningProposal() constant returns (uint8 winningProposal) {
uint256 winningVoteCount = 0;
for (uint8 proposal = 0; proposal < proposals.length; proposal++)
if (proposals[proposal].voteCount > winningVoteCount) {
winningVoteCount = proposals[proposal].voteCount;
winningProposal = proposal;
}
VoteEnded();
}
...
I am able to deploy this contract and vote etc. in Web3j. Then I added a filter to listen to VoteEnded. I did it like:
EthFilter filter = new EthFilter(DefaultBlockParameterName.EARLIEST, DefaultBlockParameterName.LATEST, contract.getContractAddress());
web3.ethLogObservable(filter).subscribe(new Action1<Log>() {
@Override
public void call(Log log) {
System.out.println("log.toString(): " + log.toString());
}
});
However this doesn't print anything at all.
What am I doing wrong?
Upvotes: 2
Views: 4323
Reputation: 11991
When listening to a local truffle based node I had to add .substring(2):
EthFilter filter = new EthFilter(DefaultBlockParameterName.EARLIEST, DefaultBlockParameterName.LATEST, contract.getContractAddress().substring(2);
Second, you probably need to use
String encodedEventSignature = EventEncoder.encode(event);
filter.addSingleTopic(encodedEventSignature);
Where event in your case should look like
new Event("VoteEnded",
Arrays.<TypeReference<?>>asList(), Arrays.<TypeReference<?>>asList());
Upvotes: 3
Reputation: 1835
You need to add filter.addSingleTopic(EventEncoder.encode(event))
where event
is an instantiated org.web3j.abi.datatypes.Event
object.
Upvotes: 2