What are the advantages and disadvantages of using encapsulation in object-oriented programming?

Advantages of encapsulation:

• Hiding internal implementation: the details of an object's operation are hidden from the outside world, allowing internal implementation to be changed without affecting the code that uses the object.
• Data protection: access to object fields is controlled through methods, preventing incorrect modification of the state.
• Simplifying maintenance and extension: changes are localized within the class.

Disadvantages of encapsulation:

• Increased code volume: the need to write getters and setters for field access.
• Potential performance reduction: method calls for access may be slower than direct field access (although in modern languages this is usually negligible).
• Complexity with excessive use: over-encapsulation can lead to many small methods and complicate the code.

Example in Java:

public class User {
    private String name; // encapsulated field

    public String getName() {
        return name;
    }

    public void setName(String name) {
        if(name != null && !name.isEmpty()) {
            this.name = name;
        }
    }
}

Here, the name field is protected from direct access, and through methods, data correctness can be controlled.