I trying to listen events from smart contract but my code isn't working. what's the problem?

Event event = droneChain.UPDATEMISSIONSTATE_EVENT;
String encodedEventSignature = EventEncoder.encode(event);
EthFilter filter = new EthFilter(DefaultBlockParameterName.LATEST, DefaultBlockParameterName.LATEST,contractAddr).addSingleTopic(encodedEventSignature);
droneChain.updateMissionStateEventObservable(filter).subscribe(updateMissionStateEventResponse -> {Toast.makeText(MapsActivity.this, updateMissionStateEventResponse._from, Toast.LENGTH_SHORT);

here is my code.

any body help me

1 Answer 1


You should call ethLogFlowable after filter definition as follow:

web3j.ethLogFlowable(filter).subscribe(log -> {
            System.out.println("Event log: "+log);
            List<Type> params = FunctionReturnDecoder.decode(
                    log.getData(), my_event.getParameters());
            System.out.println("Event param 0: "+params.get(0).getValue()); ...


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