You are designing a banking application where account balance must never be set to a negative value. Which encapsulation approach best supports this requirement?

hard🌍 Real-world Scenario Q9 of Q15

OOP & Design Patterns - Encapsulation - Data Hiding, Getters/Setters & Access Modifiers

AMake balance public and rely on external code to validate

BProvide only a public getter and no setter for balance

CUse protected balance field accessible by subclasses for validation

DUse a private balance field with a setter that validates input before updating

Step-by-Step Solution

Solution:

Step 1: Identify encapsulation for validation
Private field with setter validation ensures balance cannot be set negative internally.
Final Answer:
Option D -> Option D
Quick Check:
Setter validation enforces business rules [OK]

Quick Trick: Setters enforce validation rules internally [OK]

Common Mistakes:

MISTAKES

Making balance public trusting external validation
Using getter-only which prevents updates
Using protected exposing to subclasses without control

Trap Explanation:

PITFALL

Candidates may underestimate importance of internal validation via setters.

Interviewer Note:

CONTEXT

Evaluates ability to apply encapsulation to enforce invariants.

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You are designing a banking application where account balance must never be set to a negative value. Which encapsulation approach best supports this requirement?

Step 1: Identify encapsulation for validation

Final Answer:

Quick Check:

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