Snippet for filtering events in web3j

event_filter_web3j.java

public static void main(String[] args) throws IOException {
        List<TypeReference<?>> eventParamTypes = new ArrayList<>();
        eventParamTypes.add(new TypeReference<Utf8String>(false) {});
        eventParamTypes.add(new TypeReference<Bytes32>(true) {});
        eventParamTypes.add(new TypeReference<Address>(true) {});
        eventParamTypes.add(new TypeReference<Uint>(false) {});
        eventParamTypes.add(new TypeReference<Uint>(false) {});
        Event event = new Event("NameRegistered", eventParamTypes);
        List<EthLog.LogResult> results = getFilteredEventLogs(
                event,
                "0xF0AD5cAd05e10572EfcEB849f6Ff0c68f9700455",
                1,
                "0x4e19170565065d892c3ef9fdbd0b783a22f9b5de31d8ef18ddc35afe4615741b"
        );
        System.out.println(results);
    }

    public static List<EthLog.LogResult> getFilteredEventLogs(
            Event event,
            String contractAddress,
            int chainId,
            String ... optionalTopics
    ) throws IOException {
        String eventHash = EventEncoder.encode(event);
        EthFilter filter = new EthFilter(
                DefaultBlockParameterName.EARLIEST, // From block 0
                DefaultBlockParameterName.LATEST,  // To latest
                contractAddress) // Unique Smart Contract
                .addSingleTopic(eventHash)
                .addOptionalTopics(optionalTopics);
        EthLog response = getWeb3jService(chainId).ethGetLogs(filter).send();
        return response.getLogs();
    }

Output:

Log{removed=false, logIndex='0x2b', transactionIndex='0xb', transactionHash='0x4de8e88a5cbf341852ea2ec4a58abcf5f059bb67966c6d3aec37a890fe4b5070', blockHash='0x55def974961a8e200de4daabeb6ad334e6ac05c7e14f17c019dd6e53d2fea26c', blockNumber='0x7f5835', address='0xf0ad5cad05e10572efceb849f6ff0c68f9700455', data='0x000000000000000000000000000000000000000000000000000000000000006000000000000000000000000000000000000000000000000000aadc6d59d74fce000000000000000000000000000000000000000000000000000000006115c9c2000000000000000000000000000000000000000000000000000000000000000b7361746f73686972696368000000000000000000000000000000000000000000', type='null', topics=[0xca6abbe9d7f11422cb6ca7629fbf6fe9efb1c621f71ce8f02b9f2a230097404f, 0x4e19170565065d892c3ef9fdbd0b783a22f9b5de31d8ef18ddc35afe4615741b, 0x000000000000000000000000f8bf2546b61a4b7a277d118290dc9dcbb34d29a6]}