Question 187 of 519

Utilizing Java Object-Oriented Approach →easyMultiple ChoiceObjective-mapped

Open/Closed Principle — Using Interfaces and Dependency Injection

This 1Z0-829 practice question tests your understanding of utilizing java object-oriented approach. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

You are designing a logging framework for a distributed application. The framework must support multiple output destinations (console, file, network socket) and allow clients to dynamically add new destinations at runtime without modifying existing code. Currently, the application uses a single static Logger class with methods like logToConsole(String msg) and logToFile(String msg). The team needs to refactor the code to adhere to the Open/Closed Principle and support extensibility. After reviewing the requirements, you propose using a combination of an interface and a strategy pattern. However, a senior developer argues that using a simple enum with abstract methods would be sufficient. Which course of action best adheres to object-oriented design principles and allows the most flexibility for future extensions?

A
Keep the existing static methods but add a new method for each destination as needed. Use conditional logic to select the destination at runtime.
Why wrong: This requires modifying the Logger class for each new destination, violating Open/Closed Principle and leading to code duplication.
B
Refactor Logger to be an interface, and implement concrete destination classes (ConsoleLogger, FileLogger, SocketLogger). Use dependency injection to pass the desired destination to the Logger client.
This follows the strategy pattern and Open/Closed Principle, allowing new destinations to be added without modifying existing code.
C
Create an enum LogDestination with values CONSOLE, FILE, SOCKET, each overriding an abstract log(String) method. The Logger class uses a static method that accepts a LogDestination and calls its log method.
Why wrong: Adding a new destination requires modifying the enum, which violates Open/Closed Principle.
D
Refactor Logger to be an abstract class with an abstract log method, and create subclasses for each destination. Use a factory method to instantiate the correct subclass.
Why wrong: Although better than B or C, adding a new destination still requires modifying the factory, and abstract classes are less flexible than interfaces for multiple inheritance of type.

Full breakdown with real-world context →

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

Refactor Logger to be an interface, and implement concrete destination classes (ConsoleLogger, FileLogger, SocketLogger). Use dependency injection to pass the desired destination to the Logger client.

Option B refactors Logger to be an interface and uses dependency injection, allowing clients to pass any implementation. This adheres to the Open/Closed Principle because new destinations can be added by creating new classes implementing Logger without modifying existing code. Option A (using an enum with abstract methods) violates OCP because adding a new destination requires modifying the enum. Option C (adding static methods) also requires modification of the Logger class. Option D (abstract class with subclasses and factory) still requires modifying the factory when adding new destinations, reducing flexibility.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
Keep the existing static methods but add a new method for each destination as needed. Use conditional logic to select the destination at runtime.
Why it's wrong here
This requires modifying the Logger class for each new destination, violating Open/Closed Principle and leading to code duplication.
✓
Refactor Logger to be an interface, and implement concrete destination classes (ConsoleLogger, FileLogger, SocketLogger). Use dependency injection to pass the desired destination to the Logger client.
Why this is correct
This follows the strategy pattern and Open/Closed Principle, allowing new destinations to be added without modifying existing code.
Related concept
Read the scenario before looking for a memorised answer.
✗
Create an enum LogDestination with values CONSOLE, FILE, SOCKET, each overriding an abstract log(String) method. The Logger class uses a static method that accepts a LogDestination and calls its log method.
Why it's wrong here
Adding a new destination requires modifying the enum, which violates Open/Closed Principle.
✗
Refactor Logger to be an abstract class with an abstract log method, and create subclasses for each destination. Use a factory method to instantiate the correct subclass.
Why it's wrong here
Although better than B or C, adding a new destination still requires modifying the factory, and abstract classes are less flexible than interfaces for multiple inheritance of type.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.

Detailed technical explanation

How to think about this question

This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.

KKey Concepts to Remember

Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.

TExam Day Tips

Underline the problem statement mentally.
Watch for words such as best, first, most likely and least administrative effort.
Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

A practitioner preparing for the 1Z0-829 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.

What to study next

Got this wrong? Here's your next step.

Identify which 1Z0-829 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.

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FAQ

Questions learners often ask

What does this 1Z0-829 question test?

Utilizing Java Object-Oriented Approach — This question tests Utilizing Java Object-Oriented Approach — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Refactor Logger to be an interface, and implement concrete destination classes (ConsoleLogger, FileLogger, SocketLogger). Use dependency injection to pass the desired destination to the Logger client. — Option B refactors Logger to be an interface and uses dependency injection, allowing clients to pass any implementation. This adheres to the Open/Closed Principle because new destinations can be added by creating new classes implementing Logger without modifying existing code. Option A (using an enum with abstract methods) violates OCP because adding a new destination requires modifying the enum. Option C (adding static methods) also requires modification of the Logger class. Option D (abstract class with subclasses and factory) still requires modifying the factory when adding new destinations, reducing flexibility.

What should I do if I get this 1Z0-829 question wrong?

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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