Update:

The error is all but confirmed.  I changed the clock on my computer; I made it 20 seconds faster. Thus, the blocks now have an acceptable timestamp compared to my computer. Now 100% of all new blocks are accepted like they should be.

I made a pull request on github, but it didn't pass the CI tests I guess. Still, it would be nice to have this bug fixed.

When using BitcoinJ to listen to the blockchain I get an error on the testnet:

[NioClientManager] INFO org.bitcoinj.core.MemoryPool - [192.241.225.155]:18333:
Peer announced new transaction [1] 73e8f6fcc45922fe1ac7db57ed164a0b291ce1cd8b2e2
ee1451d4bdba52896b5
[NioClientManager] ERROR org.bitcoinj.core.AbstractBlockChain - Failed to verify
 block:
org.bitcoinj.core.VerificationException: Block too far in future: 1423230446 vs
1423230444
        at org.bitcoinj.core.Block.checkTimestamp(Block.java:672)
        at org.bitcoinj.core.Block.verifyHeader(Block.java:781)
        at org.bitcoinj.core.AbstractBlockChain.add(AbstractBlockChain.java:397)

I had a look at it, and I came across a difference between how Java does timestamping versus Bitcoin Core.
In Core, I think that it defaults to using whole seconds, while in Java the default is milliseconds.

The problem arises on line 53 here:
https://code.google.com/p/bitcoinj/source/browse/core/src/main/java/com/google/bitcoin/core/Block.java?r=0208b426f5ec537cd019378d4261868af9cb9b1e

 static final long ALLOWED_TIME_DRIFT = 2 * 60 * 60; // Same value as official client.

My suggestion is that that line should be:
 static final long ALLOWED_TIME_DRIFT = 2 * 60 * 60 * 1000; // Same value as official client, converted to milliseconds

It's a problem because the timestamp allowed is different by a factor of three magnitudes compared to official client, and it's throwing exceptions about 50% of the time.

Big thank you to Mike and other devs. There's a lot of good work behind BitcoinJ. I've been using quite a few libraries, and few are as well documented as BitcoinJ.


I've experimented a bit, and wanted to provide the solutions if someone else comes across similar problems:


>Can it be done with BitcoinJ?
Yes, but since BitcoinJ is very lightweight, it won't scan the blockchain from before the program was started. So you only get the updates that happens to your address when your program is live.

Here's how you do it:
(I've borrowed a lot from the examples provided in BitcoinJ on github)

 public static void main(String[] args) {

      NetworkParameters params = MainNetParams.get();

      WalletAppKit kit = new WalletAppKit(params, new File("."), "walletappkit-example");

        kit.startAsync();
        kit.awaitRunning();

        WalletListener wListener = new WalletListener();
        kit.wallet().addEventListener(wListener);

        Address address = null;
      try {
         address = new Address(params, "1BitangoaBiPiX6dqcLCHZUjsvzsuauB2x");
      } catch (AddressFormatException e) {
         e.printStackTrace();
      }
        kit.wallet().addWatchedAddress(address);
}

//Then you need a wallet listener class:

 static class WalletListener extends AbstractWalletEventListener {

        @Override
        public void onCoinsReceived(Wallet wallet, Transaction tx, Coin prevBalance, Coin newBalance) {
            System.out.println("-----> coins resceived: " + tx.getHashAsString());
            System.out.println("received: " + tx.getValue(wallet));
            System.out.println("wallet balance: " +wallet.getBalance());
            System.out.println("prev bal: "+prevBalance.value);
            System.out.println("new bal " + newBalance.value);
            System.out.println(tx.getVersion());
        }

        @Override
        public void onTransactionConfidenceChanged(Wallet wallet, Transaction tx) {
            System.out.println("-----> confidence changed: " + tx.getHashAsString());
            TransactionConfidence confidence = tx.getConfidence();
            System.out.println("new block depth: " + confidence.getDepthInBlocks());
        }

        @Override
        public void onCoinsSent(Wallet wallet, Transaction tx, Coin prevBalance, Coin newBalance) {
            System.out.println("coins sent");
        }

        @Override
        public void onReorganize(Wallet wallet) {
        }

        @Override
        public void onWalletChanged(Wallet wallet) {
        }

        @Override
        public void onKeysAdded(List<ECKey> keys) {
            System.out.println("new key added");
        }

//        @Override
        public void onScriptsChanged(Wallet wallet, List<Script> scripts, boolean isAddingScripts) {
            System.out.println("new script added");
        }
    }
   
   
Creating unsigned transaction might not be the best way to do it. Pass instead the required information; address and amount, and have the program on the other side create a transaction from that information.

Sample: (assuming you got a class variable WalletAppKit kit)

public Transaction(NetworkParameters params, String addressTo, Coin value){
   Transaction tx1 = kit.wallet().createSend(new Address(params, addressTo), value);
}

Hi

First off, thanks to the devs for making the BitcoinJ library. The examples in there were very useful. Nice to see some code that humans can read for a change.

I'm doing research to find an API where I can do the following:

1) My program A should be able to "listen" to activity on a specific address, without having private key for that address.
The public key will not change, and can be hardcoded into the program, stored on disk or whatever works for the BitcoinJ API.

2) My program A should be able to create an unsigned transaction. (This transaction should then be stored to disk or something).
Next another program B should be able to read the content of the transaction, and if the transaction is acceptable, it should sign this transaction.
Then the transaction should be published to peers on the bitcoin network, using program A or B.

Can these things be done with bitcoinJ?

What classes / interfaces should I use to achieve these goals?

Afraid of malware?

Most questions answered here:
https://bitcointalk.org/index.php?topic=880300.msg9763122#msg9763122

Position: Marketing assistant for bitcoin business

Learn marketing; a skill that’s useful no matter how the economy goes. You get to spend time on social networks including Facebook, read and write tweets, update news, keep in contact with other people, participate on forums, and spend time learning marketing on YouTube.

Start your career early and get years of head start on your friends. Imagine how proud you can be when thinking to yourself “I have a job, on the internet, and I get paid in bitcoin!”
It’s a perfect job for a young person still living at home with parents, and who want to skip many steps and go straight for a job where you get to use your brain.
You’ll be learning very valuable work skills in real life business situations.  This job could be the start of a very good career, as you’ll be learning skills that nobody else in your class will learn, and most have to go to college to learn these skills. Your teachers will not be able to understand the things you’ll be learning.
You don’t need any job experience, and we don’t care how young you are, if you’re male or female, what color your skin is or what country you’re from (except if you’re from the US; we just don’t want any trouble). What we do care about though, is how you think about work.
You’ll be working from home, and we’ll help you install the required software on your computer, and before long you’ll be learning about marketing and creating your own work.

Requirements for this job:
•   You must like to have dialogue with others on forums, Facebook etc.
•   You must have used Facebook and Twitter before, as these will be part of your job.
•   You must be motivated to learn marketing and to make money.
•   You must be able to follow our guidelines for language use. In this job you are not free to use your regular language. It’s not difficult guidelines though.
•   You must be interested in Bitcoin, since you’ll be working with a Bitcoin business.
•   You must be able to read, write and speak English. All communication with others is in English. You don’t have to be native English speaker though.
•   You must be able to send and receive emails, open attachments, word documents etc.
•   You must be able to navigate around in Windows, open programs, close programs and install programs etc. We’ll help you a lot, but if you have never installed a program before, this job might not be for you.
•   You must accept that this job will take you time; many hours per day. So if you got a tight schedule already, this job is probably not for you.
•   You’ll be working 6-7 days per week, but are allowed to reduce the hours in the weekend to a minimum.
•   You must be willing to follow instructions on the screen, and not be distracted too much.
•   You must have Windows XP or 7. We haven’t got our software working on Win8, Mac and Linux.
•   You need 1 Gigabyte of free space on your hard drive. Most computers these days have that.
•   You must have administrator access on the computer, because you’ll have to install some programs to be able to do the work, including TrueCrypt. If you don’t know what I’m talking about, that’s all right. Basically you have to own a computer or borrow your parent’s computer. If you only have access to an internet café, a school computer or similar, we sadly can’t offer you a job at this time.
•   Since we spend time and money training you, we strongly prefer that you stay with us for 6 months or more.

Payment terms
You’ll be paid on a monthly basis. Payments will occur before the 8th of every month. So you’ll work for example January, then you’ll be paid before the 8th of February to your bitcoin address according to a contract. You’ll be paid for hours worked, in bitcoin.
So what are you waiting for?


Send me an email, and I’ll help you get started on your very first CV and apply for the first job in your life.
jobs   {at]  bitango.me

Title on your email should be:
Application marketing assistant Part 1
Then you can add the following text in the email:
Hi Jared
I might be interested in the marketing assistant job.
Please tell me what a CV is, and how I can create my first CV and maybe get this job.
Regards,
[your nickname]

Personal info: answered already, just need an email for initial communication.
Motivation: it's weekend, I spend fewer hours working then.

Just email. We encourage use of nickname. You have to have an email initially for communication, but we provide email later.

I think Bitango already has some reputation. We've hired 5-15 people (don't have the exact number), and I think it's hard to find any blog post about us being scammers, because we've paid our bills to keep it this way, even if the other part was in the wrong.

I was hoping to find an escrow that was 100% automated. I don't think it will be difficult to build reputation though, but we'll see.

The basics are the same: debits and credits. Assets and liabilities. Income and expenses.

This is not the US.

McDonalds is hiring kids, because they're fast, smart, agile and cheap.

We're hiring kids because they're fast, smart, agile and cheap.



Of course we are, and we're proud of it. We're offering a skill that's very uniqe, bookkeeping in bitcoin. Can hardly get better for your career than that. Think flipping burgers at McDonalds makes you equally smart? Think school is better?



We just don't want any trouble.

If we scamming kids, aiming specifically at people with little experience, we deserve very negative reputation.

You'll see. There will probably be hiccups along the way, as this is the first time we're hiring kids. So it's not going to be perfect.
But scammers? No, that's too risky.

We're funded and can pay the bills. And we got systems to do bookkeeping.

So far we have 10 applicants showing interest. Sadly it's just one position, but we got some people with really good skills and potential.

Hopefully we'll close with the best applicant within 24-48 hours.

If I wanted to scam or install malware, wouldn't I try to install on all 10? Why select just 1?

Excellent. Please send application to jobs((([[[{at}}}}bitango.me

The US is considered to be very hostile around the world. By not providing services to the US, and by not using US people, we're reducing the risk of being attacked. A lot of people in the bitcoin industry is distancing themselves from the US for these reasons, including Monetas, Coinapult and many other start-ups.

Please send an application: jobs[((aaaat)]]bitango.me. Escrow is not a problem, but I prefer some automated service, because this is repeat business and it have to be easy and fast to do.

I found this service that seems reasonable, though I have to look deeper into it:
http://btcrow.com/

Thanks. I want it to be as easy as possible, and dealing with individuals and back and forth seems like a lot of work. I looked around and found this service, seems reasonable:
http://btcrow.com/

Have you sent email to jobs [[[at)bitango.me yet?

We got some very strong applicants, but you're still welcome to apply.

As stated before, we don't want any trouble, so we don't hire people from the US.
This is not even close to being a 1000 dollar/month job. This is a job to learn from, not to pay your bills.

USD is the biggest international currency, it's used the world over. If I gave up the amounts in any other currency, almost nobody would understand how much money it was, and they would have to spend 15 minutes figuring out how much money it was.

$200 might not be much if you're a software engineer in Silicon Valley, but it might be a lot more in a place like Argentina where your dad is making just a little more per month as you. Besides, we're not claiming it's much. We're claiming that you'll learn good skills.