Added multithreading

src/Main.java

@@ -1,16 +1,25 @@
-import model.BlockChain;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.Scanner;
 import java.util.stream.IntStream;
+import model.BlockChain;
+import model.Miner;
 
 public final class Main {
-    public static void main(final String[] args) {
+    public static void main(final String[] args) throws InterruptedException {
         final var sc = new Scanner(System.in);
         System.out.print("Enter how many zeros the hash must start with: ");
         final var hashZeroes = sc.nextInt();
         final var blockChain = new BlockChain(hashZeroes);
         blockChain.load();
 
-        IntStream.range(0, 5).forEach(block -> blockChain.addBlock());
+        final List<Miner> miners = new ArrayList<>();
+        IntStream.range(0, 5).forEach(minerId -> miners.add(new Miner(minerId, blockChain)));
+        miners.forEach(Thread::start);
+
+        for (final Miner miner : miners) {
+            miner.join();
+        }
 
         System.out.println(blockChain);
         blockChain.save();

src/model/Block.java

@@ -11,6 +11,7 @@ public class Block implements Serializable {
 
   private static final long serialVersionUID = 1L;
   private final String previousBlockHash;
+  private final int minerId;
   private final int id;
   private final int hashZeroes;
   private final long timeStamp;
@@ -19,8 +20,9 @@ public class Block implements Serializable {
   private int magicNumber;
   private float generationSecs = 0;
 
-  public Block(final String previousBlockHash, final int id, final int hashZeroes) {
+  public Block(final String previousBlockHash,final int minerId, final int id, final int hashZeroes) {
     this.previousBlockHash = previousBlockHash;
+    this.minerId = minerId;
     this.id = id;
     this.hashZeroes = hashZeroes;
     this.timeStamp = new Date().getTime();
@@ -53,6 +55,7 @@ public class Block implements Serializable {
 
   public String toString() {
     return "Block: " + "\n"
+        + "Created by miner #" + this.minerId + "\n"
         + "Id: " + this.id + "\n"
         + "Timestamp: " + this.timeStamp + "\n"
         + "Magic number: " + this.magicNumber + "\n"
@@ -61,3 +64,4 @@ public class Block implements Serializable {
         + "Block was generating for: " + this.generationSecs + " seconds" + "\n";
   }
 }
+

src/model/BlockChain.java

@@ -13,10 +13,10 @@ public class BlockChain {
     this.hashZeroes = hashZeroes;
   }
 
-  public void addBlock() {
+  public synchronized void addBlock(final int minerId) {
     final int nextId = blockList.size();
     final String previousBlockHash = (nextId > 0) ? blockList.get(nextId - 1).getBlockHash() : "0";
-    blockList.add(new Block(previousBlockHash, nextId, hashZeroes));
+    blockList.add(new Block(previousBlockHash, minerId, nextId, hashZeroes));
   }
 
   public boolean validateBlockchain() {

src/model/Miner.java

@@ -0,0 +1,17 @@
+package model;
+
+public class Miner extends Thread {
+
+  private final int minerId;
+  private final BlockChain blockChain;
+
+  public Miner(final int minerId, final BlockChain blockChain) {
+    this.minerId = minerId;
+    this.blockChain = blockChain;
+  }
+
+  @Override
+  public void run() {
+    blockChain.addBlock(minerId);
+  }
+}