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The Abi class provides powerful helpers for working with Ethereum’s Application Binary Interface (ABI).

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Function Selectors

Compute the 4-byte function selector for any function signature. 
import io.brane.contract.Abi;
import io.brane.core.types.HexData;

// "transfer(address,uint256)" -> 0xa9059cbb
HexData selector = Abi.functionSelector("transfer(address,uint256)");

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Event Topics

Compute the 32-byte topic hash for an event signature. 
import io.brane.contract.Abi;
import io.brane.core.types.Hash;

// "Transfer(address,address,uint256)" -> 0xddf252...
Hash topic = Abi.eventTopic("Transfer(address,address,uint256)");

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Decoding Events

Decode raw logs into Java objects using Abi.decodeEvents. 
import io.brane.rpc.PublicClient;
import io.brane.rpc.LogFilter;
import io.brane.contract.Abi;

PublicClient client = ...;
LogFilter filter = ...;
Abi abi = ...;

// 1. Define the Event Class
public static class TransferEvent {
    public Address from;
    public Address to;
    public BigInteger value;
}

// 2. Fetch Logs
var logs = client.getLogs(filter);

// 3. Decode
var transfers = abi.decodeEvents("Transfer", logs, TransferEvent.class);

for (var event : transfers) {
    System.out.println("Transfer: " + event.value);
}

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FastAbiEncoder

For zero-allocation, low-level encoding of arguments (useful for manual eth_call construction). 
import io.brane.core.abi.FastAbiEncoder;
import io.brane.core.abi.UInt;

byte[] encoded = FastAbiEncoder.encode(List.of(
    new UInt(256, BigInteger.TEN)
));