💩 Yikes, this is hard

src/Customer.java

@@ -2,12 +2,13 @@ public class Customer implements Runnable {
     private final PastryShop shop;
 
     public Customer(PastryShop shop) {
+        System.out.println("I'm hungry");
         this.shop = shop;
     }
 
     @Override
     public void run() {
-        //TODO
+        System.out.println("customer running...");
         shop.get();
     }
 }

src/Main.java

@@ -4,9 +4,13 @@ public class Main {
 
         Thread producer1 = new Thread(new PastryChef(shop));
         Thread consumer1 = new Thread(new Customer(shop));
-        /*
+        Thread consumer2 = new Thread(new Customer(shop));
+        Thread consumer3 = new Thread(new Customer(shop));
+
         producer1.start();
         consumer1.start();
-         */
+        consumer2.start();
+        consumer3.start();
+
     }
 }

src/PastryChef.java

@@ -2,12 +2,13 @@ public class PastryChef implements Runnable {
     private final PastryShop shop;
 
     public PastryChef(PastryShop shop) {
+        System.out.println("I'm a chef");
         this.shop = shop;
     }
 
     @Override
     public void run() {
-        //TODO
+        System.out.println("chef running...");
         shop.put(new Pastry());
     }
 }

src/PastryShop.java

@@ -1,23 +1,53 @@
 import java.util.ArrayList;
-import java.util.List;
+import java.util.Arrays;
 
-public class PastryShop {
-    private final List<Pastry> stock = new ArrayList<>();
+public class PastryShop extends ArrayList<Pastry> {
+    private static final int MAX_STOCK_SIZE = 20;
 
-    int head = 0, tail = 0; // probably wrong
+    public synchronized void put(Pastry pastry) {
+        while (getStock() == MAX_STOCK_SIZE) {
+            try {
+                System.out.println(getStock() + " pastries, producer blocked");
+                this.wait();
+            } catch (InterruptedException ex) {
+                // TODO what else can we do here?
+                System.err.println(Arrays.toString(ex.getStackTrace()));
+            }
+        }
+        while (getStock() < MAX_STOCK_SIZE) {
+            this.add(pastry);
+            System.out.println("A Pastry was put in the shop -- " + getStock() + " remaining");
 
-    public boolean put(Pastry pastry) {
-        //TODO
-        stock.add(tail, pastry);
-        return true;
+            this.notify();
+        }
     }
 
-    public Pastry get() {
-        //TODO
-        return stock.get(head);
+    public synchronized Pastry get() {
+        while (getStock() == 0) {
+            try {
+                System.out.println(getStock() + " pastries, consumer blocked");
+                this.wait();
+            } catch (InterruptedException ex) {
+                // TODO what else can we do here?
+                System.err.println(Arrays.toString(ex.getStackTrace()));
+            }
+
+        }
+
+        Pastry res = this.get(0);
+        this.remove(res);
+        System.out.println("A Pastry was got from the shop -- " + getStock() + " remaining");
+
+        this.notify();
+
+        return res;
     }
 
     public int getStock() {
-        return stock.size();
+        return this.size();
+    }
+
+    public synchronized void prime() {
+        this.notify();
     }
 }