the signup window now closes automatically after completion

src/main/java/SignUpGUI.java

@@ -56,6 +56,7 @@ public class SignUpGUI extends JFrame implements ActionListener {
                 CreateUser user = CreateUser.createUser(randomUUID.toString(), username, password, birthday);
                 user.saveToJsonFile("user.json");
                 JOptionPane.showMessageDialog(this, "User signed up successfully!");
+                dispose();
             } catch (IllegalArgumentException ex) {
                 JOptionPane.showMessageDialog(this, "Error: " + ex.getMessage(), "Sign Up Error", JOptionPane.ERROR_MESSAGE);
             }

user.json

@@ -16,5 +16,11 @@
     "userName": "asdasdasd",
     "password": "1231412512",
     "birthday": "1111111"
+  },
+  {
+    "id": "f2775f81-564b-4101-8e86-ce879a9e7737",
+    "userName": "asd",
+    "password": "asdasdasd",
+    "birthday": "asd"
   }
 ]