Read

You can call functions in Smart Contract via "Call" RPC API. What you can call here is limited to view functions that is not changing any states in the Contract.

Import necessary classes from the Web3j and kaia libraries(web3j-ext).

Connect to the Kaia blockchain using Web3j and specify the URL

Create KlayCredentials using the private key

Specify the address of the contract

Define gas price and gas limit for the transaction

Create a gas provider with static gas price and gas limit

Load the contract using contact address, Web3j instance, credentials, and gas provider. You can read and write the contract through this instance

Call the counter.number().send() function of the contract to retrieve the stored value

ReadContractExample.java

package org.web3j.example.contracts;

import java.math.BigInteger;

import org.web3j.crypto.KlayCredentials;

import org.web3j.tx.response.PollingTransactionReceiptProcessor;

import org.web3j.tx.response.TransactionReceiptProcessor;

import org.web3j.example.keySample;

import org.web3j.protocol.http.HttpService;

import org.web3j.protocol.kaia.Web3j;

import org.web3j.tx.gas.StaticGasProvider;

public class ReadContractExample {

/**

* @throws Exception

*

*/

public static void run() throws Exception {

Web3j web3j = Web3j.build(new HttpService(keySample.BAOBAB_URL));

KlayCredentials credentials = KlayCredentials.create(keySample.LEGACY_KEY_privkey);

String contractAddr = "0x95Be48607498109030592C08aDC9577c7C2dD505";

BigInteger GAS_PRICE = BigInteger.valueOf(50000000000L);

BigInteger GAS_LIMIT = BigInteger.valueOf(6721950);

StaticGasProvider gasProvider = new StaticGasProvider(GAS_PRICE, GAS_LIMIT);

Counter counter = Counter.load(contractAddr, web3j, credentials.convertToCredentials(), gasProvider);

System.out.println("Contract Call(number) Result : " + counter.number().send());

}

}

output

❯ java ReadContractExample.java

Contract Call(number) Result : 297