Client and backend. This class is shared: the same code is compiled into your app and into your server, so everything on this page works in both.

public final class Abi

Object
Abi

The Solidity contract ABI: function selectors, call data and return values.

EvmAddress recipient = EvmAddress.parse("0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed");
UInt256 amount = UInt256.parseUnits("25", 6);
byte[] data = Abi.encodeCall("transfer(address,uint256)", recipient, amount);
byte[] returned = new byte[32];                   // what eth_call answered
List<Object> out = Abi.decode("(uint256)", returned);   // [UInt256]

Types are written as in a Solidity signature: uint8..uint256, int8..int256, address, bool, bytes1..bytes32, bytes, string, arrays T[] and T[k], and tuples (T1,T2). Values map to Java as:

ABI	encode accepts	decode answers
`uintN`	`UInt256`, `Long`, `Integer`, decimal or `0x` `String`	`UInt256`
`intN`	`Long`, `Integer`, decimal `String`	`Long` up to 64 bits, decimal `String` above
`address`	`EvmAddress` or its `String`	`EvmAddress`
`bool`	`Boolean`	`Boolean`
`bytesN`, `bytes`	`byte[]`	`byte[]`
`string`	`String`	`String`
arrays, tuples	`List` or `Object[]`	`List<Object>`

Methods

`public static byte[] selector(String signature)`	The 4-byte selector of a function signature such as `transfer(address,uint256)`.
`public static byte[] eventTopic(String signature)`	The topic 0 of an event signature such as `Transfer(address,address,uint256)`.
`public static byte[] encodeCall(String signature, Object... args)`	The call data for a function: its selector followed by the encoded arguments.
`public static byte[] encode(String tupleType, Object... values)`	Encodes values against a tuple type such as `(address,uint256[],string)`.
`public static` `List<Object> decode(String tupleType, byte[] data)`	Decodes ABI bytes against a tuple type, answering one value per member.
`public static` `List<Object> decodeHex(String tupleType, String hex)`	`decode` from `0x` hex, the form `eth_call` returns.

Inherited methods

From Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait, clone, finalize

Method details

selector

public static byte[] selector(String signature)

The 4-byte selector of a function signature such as transfer(address,uint256).

eventTopic

public static byte[] eventTopic(String signature)

The topic 0 of an event signature such as Transfer(address,address,uint256).

encodeCall

public static byte[] encodeCall(String signature, Object... args)

The call data for a function: its selector followed by the encoded arguments.

Parameters

signature String: name(type1,type2,...)
args Object...: one value per parameter

encode

public static byte[] encode(String tupleType, Object... values)

Encodes values against a tuple type such as (address,uint256[],string).

decode

public static List<Object> decode(String tupleType, byte[] data)

Decodes ABI bytes against a tuple type, answering one value per member.

decodeHex

public static List<Object> decodeHex(String tupleType, String hex)

decode from 0x hex, the form eth_call returns.