- A
Step 1: Declare private static volatile instance variable; Step 2: Make constructor private; Step 3: Provide public static getInstance() method; Step 4: Inside getInstance, perform first null check, synchronize on class, second null check, then instantiate.
This is the correct order because the volatile variable ensures visibility across threads, the private constructor prevents external instantiation, the getInstance method provides the global access point, and double-checked locking reduces synchronization overhead while maintaining thread safety.
- B
Step 1: Make constructor private; Step 2: Declare private static volatile instance variable; Step 3: Provide public static getInstance() method; Step 4: Inside getInstance, perform first null check, synchronize on class, second null check, then instantiate.
Why wrong: This order is incorrect because the instance variable must be declared before the getInstance method uses it, but placing the constructor before the variable is valid. However, the correct order typically declares the variable first to emphasize its static nature. More importantly, the sequence of steps is not strictly wrong but optimal ordering is variable first.
- C
Step 1: Declare private static volatile instance variable; Step 2: Provide public static getInstance() method; Step 3: Make constructor private; Step 4: Inside getInstance, perform first null check, synchronize on class, second null check, then instantiate.
Why wrong: This order is incorrect because the constructor should be made private before defining the getInstance method that relies on it. If the constructor is not private, external code could create instances, breaking the singleton pattern.
- D
Step 1: Declare private static volatile instance variable; Step 2: Make constructor private; Step 3: Inside getInstance, perform first null check, synchronize on class, second null check, then instantiate; Step 4: Provide public static getInstance() method.
Why wrong: This order is incorrect because the getInstance method must be defined before its implementation logic. The method declaration (Step 4) should come before the body (Step 3).
1Z0-829 Working with Streams and Lambda Expressions Practice Question
This 1Z0-829 practice question tests your understanding of working with streams and lambda expressions. 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.
Order the steps to properly implement the Singleton pattern with lazy initialization in Java.
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
Step 1: Declare private static volatile instance variable; Step 2: Make constructor private; Step 3: Provide public static getInstance() method; Step 4: Inside getInstance, perform first null check, synchronize on class, second null check, then instantiate.
The correct order for implementing the Singleton pattern with lazy initialization and double-checked locking is A. The steps must follow a logical sequence: first declare the private static volatile instance variable to ensure visibility across threads, then make the constructor private to prevent external instantiation, then provide the public static getInstance method, and finally implement double-checked locking inside the method. Option B is incorrect because it declares the instance variable after making the constructor private, which is not the standard order; while functionally similar, the proper implementation requires declaring the volatile variable first. Option C places the private constructor after the getInstance method, allowing instantiation before the constructor is private. Option D puts the double-checked locking code before the method is provided, which is syntactically invalid.
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.
- ✓
Step 1: Declare private static volatile instance variable; Step 2: Make constructor private; Step 3: Provide public static getInstance() method; Step 4: Inside getInstance, perform first null check, synchronize on class, second null check, then instantiate.
Why this is correct
This is the correct order because the volatile variable ensures visibility across threads, the private constructor prevents external instantiation, the getInstance method provides the global access point, and double-checked locking reduces synchronization overhead while maintaining thread safety.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Step 1: Make constructor private; Step 2: Declare private static volatile instance variable; Step 3: Provide public static getInstance() method; Step 4: Inside getInstance, perform first null check, synchronize on class, second null check, then instantiate.
Why it's wrong here
This order is incorrect because the instance variable must be declared before the getInstance method uses it, but placing the constructor before the variable is valid. However, the correct order typically declares the variable first to emphasize its static nature. More importantly, the sequence of steps is not strictly wrong but optimal ordering is variable first.
- ✗
Step 1: Declare private static volatile instance variable; Step 2: Provide public static getInstance() method; Step 3: Make constructor private; Step 4: Inside getInstance, perform first null check, synchronize on class, second null check, then instantiate.
Why it's wrong here
This order is incorrect because the constructor should be made private before defining the getInstance method that relies on it. If the constructor is not private, external code could create instances, breaking the singleton pattern.
- ✗
Step 1: Declare private static volatile instance variable; Step 2: Make constructor private; Step 3: Inside getInstance, perform first null check, synchronize on class, second null check, then instantiate; Step 4: Provide public static getInstance() method.
Why it's wrong here
This order is incorrect because the getInstance method must be defined before its implementation logic. The method declaration (Step 4) should come before the body (Step 3).
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.
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FAQ
Questions learners often ask
What does this 1Z0-829 question test?
Working with Streams and Lambda Expressions — This question tests Working with Streams and Lambda Expressions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Step 1: Declare private static volatile instance variable; Step 2: Make constructor private; Step 3: Provide public static getInstance() method; Step 4: Inside getInstance, perform first null check, synchronize on class, second null check, then instantiate. — The correct order for implementing the Singleton pattern with lazy initialization and double-checked locking is A. The steps must follow a logical sequence: first declare the private static volatile instance variable to ensure visibility across threads, then make the constructor private to prevent external instantiation, then provide the public static getInstance method, and finally implement double-checked locking inside the method. Option B is incorrect because it declares the instance variable after making the constructor private, which is not the standard order; while functionally similar, the proper implementation requires declaring the volatile variable first. Option C places the private constructor after the getInstance method, allowing instantiation before the constructor is private. Option D puts the double-checked locking code before the method is provided, which is syntactically invalid.
What should I do if I get this 1Z0-829 question wrong?
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
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