Application Binary Interface

The Application Binary Interface(ABI) is a data encoding scheme for working with smart contracts. The types defined in the ABI are the same as those you encounter when writing smart contracts with Solidity.

The abi package includes libraries to encode/decode ABIs.

Decode ABI

Take the function of function totalSupply() public view returns (uint256) as an example:

public BigInteger totalSupply() {
  //Construct the function
        Function totalSupply = new Function("totalSupply",
                Collections.emptyList(), Arrays.asList(new TypeReference<Uint256>() {}));
//call the function
        TransactionExtention txnExt = wrapper.constantCall(Base58Check.bytesToBase58(ownerAddr.toByteArray()), 
                Base58Check.bytesToBase58(cntrAddr.toByteArray()), totalSupply);
        //Convert constant result to human readable text
        String result = Numeric.toHexString(txnExt.getConstantResult(0).toByteArray());
        return (BigInteger)FunctionReturnDecoder.decode(result, totalSupply.getOutputParameters()).get(0).getValue();

For JST(decimal: 18), the result is:

Total Supply: 9900000000000000000000000000