diff --git a/event-aggregator/src/main/java/com/iluwatar/event/aggregator/EventEmitter.java b/event-aggregator/src/main/java/com/iluwatar/event/aggregator/EventEmitter.java
index fb6a2d0c4..b34235df5 100644
--- a/event-aggregator/src/main/java/com/iluwatar/event/aggregator/EventEmitter.java
+++ b/event-aggregator/src/main/java/com/iluwatar/event/aggregator/EventEmitter.java
@@ -43,7 +43,7 @@ public abstract class EventEmitter {
     registerObserver(obs);
   }
 
-  public void registerObserver(EventObserver obs) {
+  public final void registerObserver(EventObserver obs) {
     observers.add(obs);
   }
 
diff --git a/iterator/src/main/java/com/iluwatar/iterator/Item.java b/iterator/src/main/java/com/iluwatar/iterator/Item.java
index d505332c7..8bb540fbd 100644
--- a/iterator/src/main/java/com/iluwatar/iterator/Item.java
+++ b/iterator/src/main/java/com/iluwatar/iterator/Item.java
@@ -46,7 +46,7 @@ public class Item {
     return type;
   }
 
-  public void setType(ItemType type) {
+  public final void setType(ItemType type) {
     this.type = type;
   }
 }
diff --git a/layers/src/main/java/com/iluwatar/layers/Cake.java b/layers/src/main/java/com/iluwatar/layers/Cake.java
index 8582cf418..f6eae2ad7 100644
--- a/layers/src/main/java/com/iluwatar/layers/Cake.java
+++ b/layers/src/main/java/com/iluwatar/layers/Cake.java
@@ -75,7 +75,7 @@ public class Cake {
     return layers;
   }
 
-  public void setLayers(Set<CakeLayer> layers) {
+  public final void setLayers(Set<CakeLayer> layers) {
     this.layers = layers;
   }
 
diff --git a/layers/src/main/java/com/iluwatar/layers/CakeLayer.java b/layers/src/main/java/com/iluwatar/layers/CakeLayer.java
index dd24c819e..50632f1b0 100644
--- a/layers/src/main/java/com/iluwatar/layers/CakeLayer.java
+++ b/layers/src/main/java/com/iluwatar/layers/CakeLayer.java
@@ -66,7 +66,7 @@ public class CakeLayer {
     return name;
   }
 
-  public void setName(String name) {
+  public final void setName(String name) {
     this.name = name;
   }
 
@@ -74,7 +74,7 @@ public class CakeLayer {
     return calories;
   }
 
-  public void setCalories(int calories) {
+  public final void setCalories(int calories) {
     this.calories = calories;
   }
 
diff --git a/layers/src/main/java/com/iluwatar/layers/CakeTopping.java b/layers/src/main/java/com/iluwatar/layers/CakeTopping.java
index db63ec298..7db86d0f6 100644
--- a/layers/src/main/java/com/iluwatar/layers/CakeTopping.java
+++ b/layers/src/main/java/com/iluwatar/layers/CakeTopping.java
@@ -66,11 +66,11 @@ public class CakeTopping {
     return name;
   }
 
-  public void setName(String name) {
+  public final void setName(String name) {
     this.name = name;
   }
 
-  public int getCalories() {
+  public final int getCalories() {
     return calories;
   }