blockChain.zip

package com.neu.blockChain; import java.util.ArrayList; public class NoobChain { public static ArrayList<Block> blockchain = new ArrayList<Block>(); public static int difficulty = 5; public static void main(String[] args) { //add our blocks to the blockchain ArrayList: System.out.println("Trying to Mine block 1... "); addBlock(new Block("Hi im the first block", "0")); System.out.println("Trying to Mine block 2... "); addBlock(new Block("Yo im the second block",blockchain.get(blockchain.size()-1).hash)); System.out.println("Trying to Mine block 3... "); addBlock(new Block("Hey im the third block",blockchain.get(blockchain.size()-1).hash)); System.out.println("\nBlockchain is Valid: " + isChainValid()); String blockchainJson = StringUtil.getJson(blockchain); System.out.println("\nThe block chain: "); System.out.println(blockchainJson); } public static Boolean isChainValid() { Block currentBlock; Block previousBlock; String hashTarget = new String(new char[difficulty]).replace('\0', '0'); //loop through blockchain to check hashes: for(int i=1; i < blockchain.size(); i++) { currentBlock = blockchain.get(i); previousBlock = blockchain.get(i-1); //compare registered hash and calculated hash: if(!currentBlock.hash.equals(currentBlock.calculateHash()) ){ System.out.println("Current Hashes not equal"); return false; } //compare previous hash and registered previous hash if(!previousBlock.hash.equals(currentBlock.previousHash) ) { System.out.println("Previous Hashes not equal"); return false; } //check if hash is solved if(!currentBlock.hash.substring( 0, difficulty).equals(hashTarget)) { System.out.println("This block hasn't been mined"); return false; } } return true; } public static void addBlock(Block newBlock) { newBlock.mineBlock(difficulty); blockchain.add(newBlock); } }