src/main/java/io/zipcoder/MonkeyTypewriter.java

@@ -27,12 +27,47 @@ public class MonkeyTypewriter {
 
         // This wait is here because main is still a thread and we want the main method to print the finished copies
         // after enough time has passed.
+
+
+        UnsafeCopier u = new UnsafeCopier(introduction);
+        Thread monk1 = new Thread(u);
+        Thread monk2 = new Thread(u);
+        Thread monk3 = new Thread(u);
+        Thread monk4 = new Thread(u);
+        Thread monk5 = new Thread(u);
+        monk1.start();
+        monk2.start();
+        monk3.start();
+        monk4.start();
+        monk5.start();
+
+
+
+        SafeCopier s = new SafeCopier(introduction);
+        Thread monk6 = new Thread(s);
+        Thread monk7 = new Thread(s);
+        Thread monk8 = new Thread(s);
+        Thread monk9 = new Thread(s);
+        Thread monk0 = new Thread(s);
+        monk6.start();
+        monk7.start();
+        monk8.start();
+        monk9.start();
+        monk0.start();
+
+
+
         try {
             Thread.sleep(1000);
         } catch(InterruptedException e) {
             System.out.println("MAIN INTERRUPTED");
         }
 
+
+
         // Print out the copied versions here.
+        System.out.println(u.copied);
+        System.out.println("===================\n" + "===================");
+        System.out.println(s.copied);
     }
 }

src/main/java/io/zipcoder/SafeCopier.java

@@ -1,8 +1,26 @@
 package io.zipcoder;
 
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+
 /**
  * Make this extend the Copier like `UnsafeCopier`, except use locks to make sure that the actual intro gets printed
  * correctly every time.  Make the run method thread safe.
  */
-public class SafeCopier {
+public class SafeCopier extends Copier{
+    Lock lock = new ReentrantLock();
+
+    public SafeCopier(String toCopy) {
+        super(toCopy);
+    }
+
+    public void run() {
+        while(stringIterator.hasNext()){
+            lock.lock();
+            System.out.println(Thread.currentThread().getName());
+            copied += stringIterator.next();
+            lock.unlock();
+        }
+
+    }
 }

src/main/java/io/zipcoder/UnsafeCopier.java

@@ -10,5 +10,10 @@ public class UnsafeCopier extends Copier {
     }
 
     public void run() {
+        while (stringIterator.hasNext()){
+            copied += stringIterator.next() + " ";
+        }
+
+
     }
 }