web3j对solidity里面的struct对象， java中如何传参呢 | 登链社区

5 web3j对solidity里面的struct对象， java中如何传参呢

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solidity结构体 contract test { struct Demo { uint64 uid; uint64 amount; } function send(Demo calldata demo) public {} }

java使用web3j构建参数： @Data class Demo extends StaticStruct { public Uint64 uid; public Uint64 amount; public Demo(long uid, long amount) { super(new Type[]{new Uint64(uid),new Uint64(amount)}); } 构建参数可以用这种方式吗？现在发现上链死活失败 Function function = new Function( "send", List.of(new Demo(1,2)), Collections.emptyList());

第二个问题是 java种怎么打印出来传输的参数呢？
像js就直接是json串 { "uid":1, "amount":2 }

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3 个回答

Wade - Footprint Analytics CTO 2024-09-04 16:08

　擅长：数据分析,GameFi,NFT

Wade - Footprint Analytics CTO 2024-09-10 17:20

　擅长：数据分析,GameFi,NFT

```js
pragma solidity ^0.8.0;

contract Test {
    struct Demo {
        uint64 uid;
        uint64 amount;
    }

function send(Demo calldata demo) public {
        // Function implementation
    }
}

```
java

```js
import org.web3j.abi.datatypes.StaticStruct;
import org.web3j.abi.datatypes.generated.Uint64;
import lombok.Data;

@Data
public class Demo extends StaticStruct {
    public Uint64 uid;
    public Uint64 amount;

public Demo(long uid, long amount) {
        super(new Uint64(uid), new Uint64(amount));
        this.uid = new Uint64(uid);
        this.amount = new Uint64(amount);
    }

@Override
    public String toString() {
        return "{ \"uid\": " + uid.getValue() + ", \"amount\": " + amount.getValue() + " }";
    }
}
```
调用

```js
import org.web3j.abi.datatypes.Function;
import org.web3j.protocol.core.methods.response.TransactionReceipt;
import org.web3j.tx.Contract;
import org.web3j.tx.gas.DefaultGasProvider;

import java.util.Collections;
import java.util.List;

public class Main {
    public static void main(String[] args) {
        // Initialize Web3j, credentials, and contract instance
        // Web3j web3j = Web3j.build(new HttpService("http://localhost:8545"));
        // Credentials credentials = WalletUtils.loadCredentials("password", "path/to/walletfile");
        // String contractAddress = "0xYourContractAddress";
        // Test contract = Test.load(contractAddress, web3j, credentials, new DefaultGasProvider());

// Create a Demo instance
        Demo demo = new Demo(1, 2);
        System.out.println("Demo instance: " + demo);

// Create a Function instance
        Function function = new Function(
            "send",
            List.of(demo),
            Collections.emptyList()
        );

// Call the contract function
        // TransactionReceipt receipt = contract.executeTransaction(function);
        // System.out.println("Transaction receipt: " + receipt);
    }
}

```

jc0803kevin - 合约开发/区块链开发/项目管理 3天前