implement equals() and hashCode()

ws/eclipse/HibIntro/src/main/java/component/emails/Email.java

@@ -13,7 +13,25 @@ public class Email {
   public Email(final String emailAddress) {
     setEmailAddress(emailAddress);
   }
-  void sendEmail(final String subject, final String content) {
-    //Not yet implemented
+  @Override
+  public int hashCode() {
+    if (null == getEmailAddress()) {
+      return System.identityHashCode(this);
+    } else {
+      return getEmailAddress().hashCode();
+    }
+  }
+  @Override
+  public boolean equals(Object obj) {
+    if (null == getEmailAddress()) {
+      return false;
+    } else if ( null == obj) {
+      return false;
+    } else if (obj instanceof Email) {
+      Email other = (Email) obj;
+      return getEmailAddress().equals(other.getEmailAddress());
+    } else {
+      return false;
+    }
   }
 }
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