Abstraction is a process where you show only “relevant” data and “hide” unnecessary details of an object from the user. Consider your mobile phone, you just need to know what buttons are to be pressed to send a message or make a call, What happens when you press a button, how your messages are sent, … Read more
Encapsulation: hiding data using getters and setters etc. Abstraction: hiding implementation using abstract classes and interfaces etc.
Why don’t I have an error message, when I set ID value in daughter class, the sentence this.id=value is executed, but how can can I access to it from my child class if it is private? When you call a public method on a class, that method can access private members of that class: public … Read more
Access to the book is by no mean necessary. The issues we are dealing here are Dependency and Reuse. In a well-designed software, you try to isolate items from one another so as to reduce Dependencies, because Dependencies are a hurdle to overcome when change is necessary. In a well-designed software, you apply the DRY … Read more
Set and Get methods are a pattern of data encapsulation. Instead of accessing class member variables directly, you define get methods to access these variables, and set methods to modify them. By encapsulating them in this manner, you have control over the public interface, should you need to change the inner workings of the class … Read more
1) why I would want to use properties instead of fields (especially when it appears I am just adding additional code You should always use properties where possible. They abstract direct access to the field (which is created for you if you don’t create one). Even if the property does nothing other than setting a … Read more
The answer is, as always, “it depends”. It depends on how big the returned collection will be. It depends on whether the result changes over time, and how important consistency of the returned result is. And it depends very much on how the user is likely to use the answer. First, note that you can … Read more
You could return an Integer instead of an int, returning null on parse failure. It’s a shame Java doesn’t provide a way of doing this without there being an exception thrown internally though – you can hide the exception (by catching it and returning null), but it could still be a performance issue if you’re … Read more
Go to the source! Grady Booch says (in Object Oriented Analysis and Design, page 49, second edition): Abstraction and encapsulation are complementary concepts: abstraction focuses on the observable behavior of an object… encapsulation focuses upon the implementation that gives rise to this behavior… encapsulation is most often achieved through information hiding, which is the process … Read more
If the class contains any template member functions you can specialize that member function to suit your needs. Even if the original developer didn’t think of it. safe.h class safe { int money; public: safe() : money(1000000) { } template <typename T> void backdoor() { // Do some stuff. } }; main.cpp: #include <safe.h> #include … Read more