Retrieve Account Balance final

[sajalbnl]

retrieve account balance #35

[trbutler4]

AI comments left in

[trbutler4]

change this name to StarknetUtils

[trbutler4]

API key should not be in codebase. Load from local.properties or similar. Here is a guide: https://medium.com/make-android/how-to-safeguard-your-api-keys-in-android-projects-with-github-secrets-5679e0e89a77

you can ignore the part about adding it to github secrets

[trbutler4]

why arent you using the starknet SDK library? It will be a lot easier to work with.

Follow the example here: https://github.com/software-mansion/starknet-jvm/blob/main/androiddemo/src/main/java/com/example/androiddemo/MainActivity.kt#L148

I have also pasted the getBalance() function from the example here:

    private suspend fun getBalance(accountAddress: Felt): Uint256 {
        // Create a call to Starknet ERC-20 ETH contract
        val call = Call(
            contractAddress = erc20ContractAddress,
            entrypoint = "balanceOf", // entrypoint can be passed both as a string name and Felt value
            calldata = listOf(accountAddress), // calldata is List<Felt>, so we wrap accountAddress in listOf()
        )

        // Create a Request object which has to be executed in synchronous or asynchronous way
        val request = provider.callContract(call)

        // Execute a Request. This operation returns JVM CompletableFuture
        val future = request.sendAsync()

        // Await the completion of the future without blocking the main thread
        // this comes from kotlinx-coroutines-jdk8
        // The result of the future is a List<Felt> which represents the output values of the balanceOf function
        val response = future.await()

        // Output value's type is UInt256 and is represented by two Felt values
        return Uint256(
            low = response[0],
            high = response[1],
        )
    }

[trbutler4]

We dont need this, we just need a provider:

  // Create a provider for interacting with Starknet
    private val provider = JsonRpcProvider(
        url = BuildConfig.DEMO_RPC_URL,
    )

the above is from the starknet sdk jvm example at: https://github.com/software-mansion/starknet-jvm/blob/main/androiddemo/src/main/java/com/example/androiddemo/MainActivity.kt#L148

please follow their example closely

[trbutler4]

Balance conversion can be handled like this:

 // Output value's type is UInt256 and is represented by two Felt values
        return Uint256(
            low = response[0],
            high = response[1],
        )

which is from the starknet jvm sdk example. This is a better approach to handle Felt type conversion

[trbutler4]

Just use the provider, and a utility class with a function to get the balance, we dont need this.