In Java, what do the access modifiers private, protected, and public mean in terms of where a member can be accessed?

Introduction / Context:
Access modifiers in Java control the visibility of classes, methods, and fields. Understanding private, protected, and public is fundamental to encapsulation and good object oriented design. Interviewers frequently ask about these modifiers to check whether you know how to restrict or expose members appropriately in different scenarios.

Given Data / Assumptions:

• We are dealing with class members such as fields, methods, and constructors.
• Classes may be in the same package or in different packages.
• There may be subclass relationships across packages.
• We want to protect internal implementation details while exposing a clear public API.

Concept / Approach:
Java provides four main access levels: private, default (package private), protected, and public. Private is the most restrictive and public is the least restrictive. Protected provides an intermediate level that is particularly useful in inheritance hierarchies. Correct usage of these modifiers enforces encapsulation and reduces unintended coupling between classes.

Step-by-Step Solution:
1. private: when a member is declared private, it can only be accessed within the same class in which it is defined. No other class, not even subclasses, can directly access it. 2. Default (no modifier): when no modifier is specified, the member is visible only within the same package. Classes in other packages cannot access it directly. 3. protected: a protected member is accessible in the same package (like default) and also in subclasses, even if those subclasses are in different packages. 4. public: a public member can be accessed from any other class, regardless of package, provided that the class itself is accessible. 5. By choosing the narrowest access level that still supports necessary usage, you improve encapsulation and reduce the surface area for bugs.

Verification / Alternative check:
You can verify access levels by creating classes in different packages and attempting to access private, protected, default, and public members. The compiler will generate errors when you break visibility rules. For example, a subclass in another package can access protected members but not default or private members of its superclass.

Why Other Options Are Wrong:
Option B is completely reversed; private does not allow access from any class, and public does not restrict access to the same package. Option C is wrong because private and protected are not identical; they differ especially in subclasses across packages. Public can definitely be used on methods. Option D is incorrect because access modifiers can be applied to several kinds of members; they are not restricted the way this option suggests.

Common Pitfalls:
Developers sometimes make too many members public for convenience, which weakens encapsulation and makes refactoring harder. Another pitfall is misunderstanding protected in cross package inheritance and assuming that it behaves like default. It is also common to forget that private members are still inherited but not directly accessible, which affects how you design getters and setters in subclasses.

Final Answer:
private restricts access to within the same class, protected allows access in the same package and in subclasses, and public allows access from any class.