web3j is not generating struct inside my solidity contract

Question

I have a struct Question in my smart contract. After generating the java wrapper class of my smart contract using web3j, Inside the wrapper class Question is not recognized, looks like web3j is not generating struct code in the wrapper class.

In short, web3j does generate a java wrapper class but forgets to handle the struct.

pragma solidity ^0.8.16;


contract Quiz{

struct Question{
    string statement;
     string[4] options;
    uint correctIndex;
}

    Question[] questions;


    constructor() payable{
        addQuestions();
    }


    function addQuestions()public payable{
         questions.push(Question("Who is the CEO of Pakistan?", ["Shehbaz Sharif","Gen. Bajwa","Imran Khan","Zardari"], 1));
         questions.push(Question("Capital of Pakistan?", ["Lahore","Quetta","Karachi","Islamabad"], 3));
         questions.push(Question("When android acquried firebase offically?", ["2011","2014","2013","2015"], 1));
         questions.push(Question("Advantages of decentralized App?", ["Speed, efficiency and accuracy","Trust and transparency","Savings","All of these"], 3));
         questions.push(Question("What are the application of smart contracts?", ["retailer-supplier","Trade Efficency","Trust","All of these"], 3));
    }

    function getQuestions()public view returns(Question[] memory){
        Question[] memory questionList = new Question[](5);
        for (uint i = 0; i < 5; i++) {
          Question storage question = questions[i];
          questionList[i] = question;
        }
        return questionList;
    }

    

    function checkQuestion(uint qIndex, uint choosedAnsIndex)public view returns(bool){
        Question memory question = questions[qIndex];

        if(question.correctIndex == choosedAnsIndex){
            return true;
        }

        return false;
    }



}

Here's the generated java wrapper class Quiz_sol_Quiz.java.

Any help would be highly appreciated.

Answer 1

Web3j offers parent classes to implement struct on Java: StaticStruct and DynamicStruct. Below is an example of my struct and its implementation on Java.

struct Value {
    string _offer;
    uint256 _availableSince;
    uint256 _availabilityEnd;
    bool _isConsumed;
    uint256 _lockedUntil;
}

class Value: DynamicStruct {

    private lateinit var offer: String
    private lateinit var availableSince: BigInteger
    private lateinit var availabilityEnd: BigInteger
    private var isConsumed: Boolean = false
    private lateinit var lockedUntil: BigInteger

    constructor(
        offer: String,
        availableSince: BigInteger,
        availabilityEnd: BigInteger,
        isConsumed: Boolean,
        lockedUntil: BigInteger
    ) : super(
        Utf8String(offer), Uint256(availableSince),
        Uint256(availabilityEnd), Bool(isConsumed),
        Uint256(lockedUntil)
    ) {
        this.offer = offer
        this.availableSince = availableSince
        this.availabilityEnd = availabilityEnd
        this.isConsumed = isConsumed
        this.lockedUntil = lockedUntil
    }

    constructor(
        offer: Utf8String,
        availableSince: Uint256,
        availabilityEnd: Uint256,
        isConsumed: Bool,
        lockedUntil: Uint256
    ) : super(offer, availableSince, availabilityEnd, isConsumed, lockedUntil) {
        this.offer = offer.value
        this.availableSince = availableSince.value
        this.availabilityEnd = availabilityEnd.value
        this.isConsumed = isConsumed.value
        this.lockedUntil = lockedUntil.value
    }

}