diff --git a/src/Client/src/main/java/greenify/client/Hints.java b/src/Client/src/main/java/greenify/client/Hints.java
index 95f010d..9d41a69 100644
--- a/src/Client/src/main/java/greenify/client/Hints.java
+++ b/src/Client/src/main/java/greenify/client/Hints.java
@@ -56,7 +56,7 @@ public class Hints {
     }
 
     /**
-     * This method gets a random hint from the list of hints.
+     * This method returns a random String.
      * @return the random hint.
      */
     public String randomHint() {
diff --git a/src/Client/src/main/java/greenify/client/controller/CalculatorController.java b/src/Client/src/main/java/greenify/client/controller/CalculatorController.java
index 4d3e4e7..ae837c2 100644
--- a/src/Client/src/main/java/greenify/client/controller/CalculatorController.java
+++ b/src/Client/src/main/java/greenify/client/controller/CalculatorController.java
@@ -14,6 +14,7 @@ import javafx.beans.value.ObservableValue;
 import javafx.event.ActionEvent;
 import javafx.fxml.FXML;
 import javafx.scene.Node;
+import javafx.scene.control.Alert;
 import javafx.scene.control.Button;
 import javafx.scene.control.CheckBox;
 import javafx.scene.control.Label;
@@ -33,6 +34,7 @@ import java.text.DecimalFormat;
 
 @Controller
 public class CalculatorController {
+    private static UserController.AlertHelper AlertHelper;
     @Autowired
     UserService userService;
 
@@ -524,5 +526,7 @@ public class CalculatorController {
         Stage current = (Stage) owner;
         current.close();
         controller.updateLeaderboard();
+        CalculatorController.AlertHelper.showAlert(Alert.AlertType.CONFIRMATION,
+                owner, "Footprint saved!", "Your footprint is saved!");
     }
 }
\ No newline at end of file
diff --git a/src/Client/src/main/java/greenify/client/controller/DashBoardController.java b/src/Client/src/main/java/greenify/client/controller/DashBoardController.java
index 1a241f6..4054ea6 100644
--- a/src/Client/src/main/java/greenify/client/controller/DashBoardController.java
+++ b/src/Client/src/main/java/greenify/client/controller/DashBoardController.java
@@ -432,7 +432,7 @@ public class DashBoardController {
     }
 
     /**
-     * method opend addFriend scene.
+     * method opens addFriend scene.
      * @throws IOException when file is not found
      */
     public void openAddFriend() throws IOException {
@@ -579,3 +579,4 @@ public class DashBoardController {
     }
 
 }
+
diff --git a/src/Client/src/main/java/greenify/client/controller/FriendController.java b/src/Client/src/main/java/greenify/client/controller/FriendController.java
index a623de5..aa2d455 100644
--- a/src/Client/src/main/java/greenify/client/controller/FriendController.java
+++ b/src/Client/src/main/java/greenify/client/controller/FriendController.java
@@ -52,7 +52,10 @@ public class FriendController {
         //add friend to the current user
         userService.addFriend(userService.currentUser.getName(), userNameText.getText());
         //close the register window after the user has entered all the credentials
+        String friendName = userNameText.getText();
         Stage current = (Stage) owner;
         current.close();
+        UserController.AlertHelper.showAlert(Alert.AlertType.CONFIRMATION, owner, "Friend added!",
+                userNameText.getText() + " is now your friend!");
     }
 }
diff --git a/src/Client/src/main/java/greenify/client/controller/RegisterWindowController.java b/src/Client/src/main/java/greenify/client/controller/RegisterWindowController.java
index 11cb71f..9ecad09 100644
--- a/src/Client/src/main/java/greenify/client/controller/RegisterWindowController.java
+++ b/src/Client/src/main/java/greenify/client/controller/RegisterWindowController.java
@@ -228,7 +228,14 @@ public class RegisterWindowController {
         }
 
         //register the user with the provided username and password
-        userService.registerUser(userNameText.getText(), passwordField.getText());
+        try {
+            userService.registerUser(userNameText.getText(), passwordField.getText());
+        }
+        catch (RuntimeException ex) {
+            UserController.AlertHelper.showAlert(Alert.AlertType.ERROR, owner, "Username Error!",
+                    "This username has already been taken!");
+            return;
+        }
         //close the register window after the user has entered all the credentials
         Stage current = (Stage) owner;
         current.close();
diff --git a/src/Client/src/main/java/greenify/client/controller/UserController.java b/src/Client/src/main/java/greenify/client/controller/UserController.java
index a67fcf9..19af71a 100644
--- a/src/Client/src/main/java/greenify/client/controller/UserController.java
+++ b/src/Client/src/main/java/greenify/client/controller/UserController.java
@@ -65,7 +65,14 @@ public class UserController {
             System.out.println("Password is " + passwordField.getText());
         }
         //log the user in with the userService method
-        userService.loginUser(usernameField.getText(), passwordField.getText());
+        try {
+            userService.loginUser(usernameField.getText(), passwordField.getText());
+        }
+        catch (RuntimeException ex) {
+            AlertHelper.showAlert(Alert.AlertType.ERROR, owner, "Log-in Error!",
+                    "Your username or password is incorrect!");
+            return;
+        }
         Stage current = (Stage) owner;
         //after logging in, close the login window
         current.close();