In object-oriented design, what does encapsulation ensure?

Encapsulation is a fundamental principle of object-oriented design that ensures all data and methods are self-contained within an object. This characteristic not only protects the internal state of an object but also helps to manage complexity by bundling the data (attributes) and the methods (functions) that operate on that data into a single unit or class. As a result, the internal workings of an object can be hidden from the outside world, allowing for controlled access through well-defined interfaces (often referred to as public methods). This promotes data integrity and reduces the likelihood of unintended interference or misuse by outside entities.

Moreover, the encapsulation principle also supports the concept of abstraction, whereby the details of the implementation are hidden, and only relevant features are exposed. This allows developers to modify and maintain the code internally without affecting other parts of the program that rely on the encapsulated object. By emphasizing that all data and methods are self-contained, encapsulation provides the structure and organization vital to scalable and maintainable software design.