all the blurst monkeys at work

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

         // Do all of the Monkey / Thread building here
         // For each Copier(one safe and one unsafe), create and start 5 monkeys copying the introduction to
         // A Tale Of Two Cities.
+        UnsafeCopier dangerWillRobinson = new UnsafeCopier(introduction);
+        new Thread(dangerWillRobinson).start();
+        new Thread(dangerWillRobinson).start();
+        new Thread(dangerWillRobinson).start();
+        new Thread(dangerWillRobinson).start();
+        new Thread(dangerWillRobinson).start();
+
+        SafeCopier safetyFirst = new SafeCopier(introduction);
+        new Thread(safetyFirst).start();
+        new Thread(safetyFirst).start();
+        new Thread(safetyFirst).start();
+        new Thread(safetyFirst).start();
+        new Thread(safetyFirst).start();
 
 
         // This wait is here because main is still a thread and we want the main method to print the finished copies
         }
 
         // Print out the copied versions here.
+        System.out.println("Unsafe Copier: ");
+        System.out.println(dangerWillRobinson.copied);
+        System.out.println("Safe Copier: ");
+        System.out.println(safetyFirst.copied);
     }
 }

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

 package io.zipcoder;
 
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+
 /**
  * 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 {
+
+    ReadWriteLock alohomora;
+
+    public SafeCopier(String toCopy) {
+        super(toCopy);
+    }
+
+    public void run() {
+        alohomora = new ReentrantReadWriteLock();
+        alohomora.writeLock().lock();
+        alohomora.readLock().lock();
+        try {
+            while (stringIterator.hasNext()) {
+                copied += stringIterator.next() + " ";
+            }
+        } finally {
+            alohomora.writeLock().unlock();
+            alohomora.readLock().unlock();
+        }
+    }
+
 }

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

     }
 
     public void run() {
+        while (stringIterator.hasNext()) {
+            copied += stringIterator.next() + " ";
+        }
     }
 }