Java and Blockchain – a match made in heaven

Java is the foundation of many products. It is no coincidence that this amazing programming language affects the cryptocurrency world (including Bitcoin). But what makes people buy USDT and how blockchain could help our world modernize for good? Let’s find out in this article.

What is blockchain?

Blockchain is an open, distributed ledger that can record transactions between two parties efficiently, in a verifiable and permanent way. Blockchain databases aren’t stored in any single location, meaning the records it keeps are truly public and easily verifiable. The data stored isn’t controlled by any one entity, meaning the system isn’t subject to the whims of any government, corporation or malicious third party.

Benefits of using blockchain

Obviously, what’s the point of discussing the topic, if we will skip the benefits of blockchain?


Blockchain is decentralized meaning it doesn’t have a governing body. No one can single-handedly decide to change how the blockchain project will continue to work, unless they own 51% of the blockchain. Since that is nearly impossible, blockchains are owned by nobody, unless it’s a private blockchain.


Immutability is what makes the blockchain so revolutionary. Unlike traditional database records, which are prone to manipulation and deletion due to centralization, blockchain records are unalterable and permanent. Every blockchain transaction is time-stamped and date-stamped, giving it a timestamp of its very occurrence, allowing users to trace the origin and evolution of any data on the chain. It, therefore, enables users to verify information over time, ensuring reliability. If you decide to buy a car with Bitcoin, nobody could ever change that.


Though it was first used to track bitcoin transactions, blockchain technology has attracted the interest of a variety of industries. Major companies like IBM, Walmart and Maersk are using blockchain to run complex global supply chains with less friction, prevent fraud and reduce waste. Beyond bringing accountability to systems where trust has been an issue, the technology can also help ensure consumer privacy.

Coding skills – not much needed

Since we care about coding, we cannot move on without giving some helpful tips on how to use Java for blockchain.

Let’s implement a block

public class Block {
    private String hash;
    private String previousHash;
    private String data;
    private long timeStamp;
    private int nonce;

    public Block(String data, String previousHash, long timeStamp) { = data;
        this.previousHash = previousHash;
        this.timeStamp = timeStamp;
        this.hash = calculateBlockHash();

    // standard getters and setters

Then, we need to work on the hashing. Bear in mind it is very sensitive. Any data altercation could be detrimental.

public String calculateBlockHash() {
    String dataToHash = previousHash
            + Long.toString(timeStamp)
            + Integer.toString(nonce)
            + data;
    MessageDigest digest = null;
    byte[] bytes = null;
    try {
        digest = MessageDigest.getInstance("SHA-256");
        bytes = digest.digest(dataToHash.getBytes(UTF_8));
    } catch (NoSuchAlgorithmException | UnsupportedEncodingException ex) {
        logger.log(Level.SEVERE, ex.getMessage());
    StringBuffer buffer = new StringBuffer();
    for (byte b : bytes) {
        buffer.append(String.format("%02x", b));
    return buffer.toString();

From what we see, we get a case of SHA-256 (cryptography), and then generate a hash value from our input data. The byte array is a very crucial part here – it is the hash value that we transform later into a hex string (usually, a 32-digit number).

But how to mine a block?

public String mineBlock(int prefix) {
    String prefixString = new String(new char[prefix]).replace('\0', '0');
    while (!hash.substring(0, prefix).equals(prefixString)) {
        hash = calculateBlockHash();
    return hash;

We start by looking for the solution. If we don’t manage to do so, we increment the nonce and calculate our hash in a loop until we finally make it. I have to tell you – it might take a long time before you hit the jackpot.

Blockchain verification

How to verify the blockchain? After all, there are plenty of fake attempts, so we need to see if our attempt is valid.

public void givenBlockchain_whenValidated_thenSuccess() {
    boolean flag = true;
    for (int i = 0; i < blockchain.size(); i++) {
        String previousHash = i==0 ? "0" : blockchain.get(i - 1).getHash();
        flag = blockchain.get(i).getHash().equals(blockchain.get(i).calculateBlockHash())
                && previousHash.equals(blockchain.get(i).getPreviousHash())
                && blockchain.get(i).getHash().substring(0, prefix).equals(prefixString);
        if (!flag) break;


Java and blockchain are made to work together. However, it is not easy to mine blockchain. That is why, we advise you to enter pools, in order to share prizes with others but ensure you are on the winning side.