diff --git a/core-java/src/main/java/com/baeldung/graph/Graph.java b/core-java/src/main/java/com/baeldung/graph/Graph.java
index 43b5c0aa08..3f2e17c43c 100644
--- a/core-java/src/main/java/com/baeldung/graph/Graph.java
+++ b/core-java/src/main/java/com/baeldung/graph/Graph.java
@@ -59,18 +59,43 @@ public class Graph {
         Vertex(String label) {
             this.label = label;
         }
-        @Override
-        public boolean equals(Object obj) {
-            Vertex vertex = (Vertex) obj;
-            return vertex.label == label;
-        }
+        
         @Override
         public int hashCode() {
-            return label.hashCode();
+            final int prime = 31;
+            int result = 1;
+            result = prime * result + getOuterType().hashCode();
+            result = prime * result + ((label == null) ? 0 : label.hashCode());
+            return result;
         }
+        
+        @Override
+        public boolean equals(Object obj) {
+            if (this == obj)
+                return true;
+            if (obj == null)
+                return false;
+            if (getClass() != obj.getClass())
+                return false;
+            Vertex other = (Vertex) obj;
+            if (!getOuterType().equals(other.getOuterType()))
+                return false;
+            if (label == null) {
+                if (other.label != null)
+                    return false;
+            } else if (!label.equals(other.label))
+                return false;
+            return true;
+        }
+
         @Override
         public String toString() {
             return label;
         }
+
+
+        private Graph getOuterType() {
+            return Graph.this;
+        }
     }
 }
\ No newline at end of file