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Legacy Account Key

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

Create a Web3j instance with the specified BAOBAB_URL

Also, you can change the default provider. For example, using the alchemy provider.

Create a credential from private key

Gas price and gas limit settings

Set the sender address equal to the loaded credential's address

Get chain ID from the network

Set the receiver address equal to any valid address

Get the nonce for the sender's address

Set the value to transfer

Set transaction type as VALUE_TRANSFER

Create a raw transaction for value transfer

Sign the transaction

Send the signed transaction to kaia network

Recover the sender address from signed transaction and compare it to the from address

Shut down the Web3j instance

SignTxWithLegacyExample.java

package org.web3j.example.accountKey;

import org.web3j.tx.response.PollingTransactionReceiptProcessor;

import org.web3j.tx.response.TransactionReceiptProcessor;

import org.web3j.example.keySample;

import java.io.IOException;

import java.math.BigInteger;

import org.web3j.crypto.KlayCredentials;

import org.web3j.crypto.KlayRawTransaction;

import org.web3j.crypto.KlayTransactionEncoder;

import org.web3j.crypto.transaction.type.TxType;

import org.web3j.crypto.transaction.type.TxType.Type;

import org.web3j.protocol.core.DefaultBlockParameterName;

import org.web3j.protocol.core.methods.response.EthChainId;

import org.web3j.protocol.http.HttpService;

import org.web3j.protocol.kaia.Web3j;

import org.web3j.protocol.kaia.core.method.response.KlayRecoverFromTransactionResponse;

import org.web3j.utils.Numeric;

import org.web3j.protocol.core.methods.response.EthSendTransaction;

/**

*

*/

public class SignTxWithLegacyExample implements keySample {

/**

*

*/

public static void run() throws Exception {

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

KlayCredentials credentials1 = KlayCredentials.create(keySample.LEGACY_KEY_privkey);

BigInteger GAS_PRICE = BigInteger.valueOf(50000000000L);

BigInteger GAS_LIMIT = BigInteger.valueOf(6721950);

String from = credentials1.getAddress();

EthChainId EthchainId = web3j.ethChainId().send();

long chainId = EthchainId.getChainId().longValue();

String to = "0x000000000000000000000000000000000000dead";

BigInteger nonce = web3j.ethGetTransactionCount(from, DefaultBlockParameterName.LATEST).send()

.getTransactionCount();

BigInteger value = BigInteger.valueOf(100);

TxType.Type type = Type.VALUE_TRANSFER;

KlayRawTransaction raw = KlayRawTransaction.createTransaction(

type,

nonce,

GAS_PRICE,

GAS_LIMIT,

to,

value,

from);

byte[] signedMessage = KlayTransactionEncoder.signMessage(raw, chainId, credentials1);

String hexValue = Numeric.toHexString(signedMessage);

EthSendTransaction transactionResponse = web3j.ethSendRawTransaction(hexValue).send();

System.out.println("TxHash : \n " + transactionResponse.getResult());

String blockNumber = "latest";

KlayRecoverFromTransactionResponse response = web3j.klayRecoverFromTransaction(hexValue, blockNumber).send();

System.out.println("Original address : " + from);

System.out.println("Result address : " + response.getResult());

web3j.shutdown();

}

}

output

❯ java SignTxWithLegacyExample.java

TxHash :

0x957734684be8f79a21cef4de1842709b84c92e3920d656165ddb951981987b5a

Original address : 0xa2a8854b1802d8cd5de631e690817c253d6a9153

Result address : 0xa2a8854b1802d8cd5de631e690817c253d6a9153