Add code for module 1, part 5, video 2

Author: SvenWoltmann

src/main/java/eu/happycoders/datastructures/module2/p5_thread_safe_lists/v02_copyonwritearraylist/CopyOnWriteArrayListDemo.java

@@ -0,0 +1,4 @@
+void main() {
+
+
+}

src/main/java/eu/happycoders/datastructures/module2/p5_thread_safe_lists/v02_copyonwritearraylist/CopyOnWriteArrayListDemoFinished.java

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+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.function.Consumer;
+
+void main() throws InterruptedException {
+  Consumer<String> observer1 = string -> System.out.println("observer 1 observed: " + string);
+  Consumer<String> observer2 = string -> System.out.println("observer 2 observed: " + string);
+  Consumer<String> observer3 = string -> System.out.println("observer 3 observed: " + string);
+
+  var subject = new CopyOnWriteArrayList<Consumer<String>>();
+  subject.add(observer1);
+  subject.add(observer2);
+  subject.add(observer3);
+
+  Thread.startVirtualThread(() -> {
+    int counter = 3;
+    while (true) {
+      int observerId = ++counter;
+      Consumer<String> observer = string -> System.out.println("observer " + observerId + " observed: " + string);
+      subject.add(observer);
+      sleepLong();
+    }
+  });
+
+  Thread.startVirtualThread(() -> {
+    while (true) {
+      subject.removeFirst();
+      sleepLong();
+    }
+  });
+
+  while (true) {
+    subject.forEach(observer -> observer.accept("message"));
+    System.out.println();
+    Thread.sleep(500);
+  }
+}
+
+private static void sleepLong() {
+  try {
+    Thread.sleep(ThreadLocalRandom.current().nextInt(1500, 2500));
+  } catch (InterruptedException e) {
+    throw new RuntimeException(e);
+  }
+}