How to pass a variable from a smart contract to java project using web3j

Question

Here is a very simple smart contract:

pragma solidity ^0.7.0;
        
contract Name {
    
    string name = "Tom";
    
    function getName() public view returns (string memory) {
        return name;
    }
}

Then I have converted this into a java file using web3j and the getName() function looks like this:

public RemoteCall<TransactionReceipt> getName() {
    final Function function = new Function(
            FUNC_GETNAME, 
            Arrays.<Type>asList(), 
            Collections.<TypeReference<?>>emptyList());
    return executeRemoteCallTransaction(function);
}

I am a little bit confused about how to get the return value of getName() function.

Answer 1

I am not sure which version of web3j you are using. Currently I am using Web3j 1.4.1. When I created wrapper class it has different return type than what you mentioned.

public RemoteFunctionCall<String> getName() {
    final org.web3j.abi.datatypes.Function function = new org.web3j.abi.datatypes.Function(FUNC_GETNAME, 
            Arrays.<Type>asList(), 
            Arrays.<TypeReference<?>>asList(new TypeReference<Utf8String>() {}));
    return executeRemoteCallSingleValueReturn(function, String.class);
}

Below is the code, I tried to work around. It is returning the name that is mentioned in the public variable.

nameContract = Name.deploy(this.web3j, this.credential, (new ContractGasProviderImplementations())).send();
        
String name = nameContract.getName().send();
        
System.out.println(name);