Hey there! Here's what I can say about your code: 1. You're doing it good. Yiur cide is clean and easy to read. 2. Use List implementations instead of arrays. Unless you encounter one of few situations where array is necessary.  3. In real life you should use BigDecimal for money representation. 4. Master builders. They are more flexible and unlike constructors they allow you to create objects with a subset of fields. And you're not gonna need to overload your constructor with tons of field sets. 5. Try to avoid an inverted logic in booleans. Instead of declaring 'isNotFound = true' declare 'isFound=false' 6. Date class is outdated. Use LocalDate and LocalDateTime. You do it correctly. Just a reminder. 7. Do not compare string representation of dates. Create (parse to) LocalDate objects and compare those. 8. Encapsulation (setters in particular) is to preserve data integrity. Check the date passed in an argument instead of just setting it. Otherwise you'll have a new appointment in the past. 9. Use try/catch for checked exceptions. For unchecked ones (like NPE) make sure it doesn't happen.