Why is protected as bad as public

If the class member declared as public then it can be accessed everywhere. If the class members declared as protected then it can be accessed only within the class itself and by inheriting and parent classes. If the class members declared as private then it may only be accessed by the class that defines the member. Some Method Overriding rules : 1. This has already been noted here, but there was no clear example. Methods defined in a parent class can NOT access private methods defined in a class which inherits from them.

They can access protected, though. Private can only be accessed by the class which defines, neither parent nor children classes. This is not strictly true. I couldn't find this documented anywhere, but you can access protected and private member varaibles in different instance of the same class, just as you would expect i. As far as it regards the properties of objects, visibility is, yes, as the examples show.

Private or not private? I get baffled whenever I see this kind of an example. If you miss the "package" keyword in PHP in order to allow access between certain classes without their members being public, you can utilize the fact, that in PHP the protected keyword allows access to both subclasses and superclasses. Best regards,. Just wanted to share a trap for the unwary. Where there are several layers of object assignments, setting the bottom object's properties as private will prevent its exposure.

However, if the bottom object has public properties, intermediate objects which are themselves set as private but are derived from the bottom object can inadvertently be exposed to updates. The following example demonstrates the phenomenon. After having the how explained, many people will still be left wondering about the why.

How should the different kinds of visibility be used in practice? Some kind of labelling for the public and private parts of an interface is certainly necessary. We need to be clear which methods will be part of the public interface and which are only used internally.

In older versions of php notionally-private functions were prefixed with an underscore - a much simpler and more elegant solution to the labelling problem. It adds a lot of unnecessary typing to what is already a keyboard-intensive job. As for enforcement.. As such, "protected" is an attempt to solve a problem which simply did not exist. Private is even worse. It specifically encourages bad object-oriented code with the use of inheritance in places where you should be thinking about separate, co-operating objects.

A feeling that classes which inherit from each other need to hide some of their bits from each other is a sure sign that you need to break the code up into separate objects.

This is exactly what encapsulation is for. How to use var to declare local variables in Java? Example What is SuppressWarnings annotation in Java? Difference between Process and Thread in Java - Ex Spring Transactional Annotation Example - How to How to create thread safe Singleton in Java - Java How to Code in Dart Programing language? Dart Hell Inner class and nested Static Class in Java with E How to append text into File in Java — FileWriter Top 5 Courses to learn Unreal Engine in - Bes How to add, subtract days, months, years, hours fr What is final in Java?

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What is Constructor in Java with Example — Constru How to sort HashMap by key and value in Java - Has How to comment uncomment single line and block of Top 10 Coursera Certifications, Courses, and Speci They are based on defensive coding carried to extremes. It is based on the idea that your classes will be used in a world where nobody else's code can be trusted not to goose your stuff. I'm sure there are situations where this is true, but I've never seen them. What I have seen is situations where things were made horribly complicated to get around protections for which there was no need, and to try to guard the consistency of data structures that were horribly over-complicated and un-normalized.

Regarding fields vs. Exposing properties gives you a way to hide the implementation. It also allows you to change the implementation without changing the code that uses it e. Many tools that work with classes using reflection only focus on properties for example, I think that some libraries for serialization work this way.

Using properties consistently makes it easier to use these standard. NET tools. Syntactical overhead is largely reduced when you're using automatically implemented properties C 3.

In fact, this allows you to make for example set protected and get public very easily, so this can be even more elegant than using fields. When you lose encapsulation, you lose the contract of the declaring class; you cannot guarantee that the class behaves as intended or expected. Using a property or a method to access the field enables you to maintain encapsulation, and fulfill the contract of the declaring class.

I agree with the read-only property answer. But to play devil's advocate here, it really depends on what you're doing. I'll be happy to admit i write code with public members all the time i also don't comment, follow guidelines, or any of the formalities. If you keep your behaviour and data separate, it is fine to expose the data of your data classes, as long as they have no behaviour. Stack Overflow for Teams — Collaborate and share knowledge with a private group.

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Improve this question. Add a comment. Active Oldest Votes. They are way, way worse. If you still need it to be read-write, apologize to your colleagues and don't do it again : A lot of developers believe - and will tell you - that this is overly strict. Improve this answer.

Rex M Rex M k 30 30 gold badges silver badges bronze badges. As soon as you make a member not-private, you are stuck with it, forever and ever. It's your public interface now. I mostly agree but I see no problem having writable protected properties.