The correct approach is to modify the method to use an ArrayList<Product> internally while keeping the method signature unchanged. This solves the problem because ArrayList in Java is backed by a dynamic array that automatically resizes when its capacity is exceeded, handling the growth without requiring manual array copying or a fixed-size constraint. On the Oracle Java Foundations 1Z0-811 exam, this question tests your understanding of dynamic array resizing with ArrayList and the principle of encapsulation—changing the internal implementation without affecting the public API. A common trap is thinking you must change the method signature to accept a collection, but the exam emphasizes that internal refactoring is sufficient. Remember the memory tip: "Keep the signature, swap the storage"—the method still takes a single Product, but the internal array becomes an ArrayList, letting Java handle the resizing automatically.
1Z0-811 Arrays and Methods Practice Question
This 1Z0-811 practice question tests your understanding of arrays and methods. 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.
A team is developing a Java application for an online store. The application has a class 'Inventory' that maintains an array of 'Product' objects. The method 'public void addProduct(Product p)' is intended to add a product to the array. The current implementation uses a fixed-size array of length 100. However, the business has grown, and the array may exceed its capacity. The team needs a solution that allows dynamic resizing without changing the method signature. Which approach should the team take?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Modify the method to use an ArrayList<Product> internally and keep the signature.
Option A is correct because using an ArrayList<Product> internally allows the array to dynamically resize as needed, while keeping the method signature unchanged. The method still accepts a Product parameter, but the internal implementation leverages ArrayList's automatic capacity management, eliminating the fixed-size constraint.
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.
✓
Modify the method to use an ArrayList<Product> internally and keep the signature.
Why this is correct
Allows dynamic resizing with same signature.
Related concept
Read the scenario before looking for a memorised answer.
✗
Change the method signature to accept a Product[] array and copy all elements.
Why it's wrong here
Changes signature; breaks existing code.
✗
Use a Collection<Product> as parameter and convert to array.
Why it's wrong here
Changes parameter type; callers must change.
✗
Change the return type to boolean and return false if array is full.
Why it's wrong here
Changes return type; callers need modification.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may think changing the return type or parameter type is acceptable, but the question explicitly requires keeping the method signature unchanged, so only internal implementation changes are allowed.
Detailed technical explanation
How to think about this question
Under the hood, ArrayList uses an internal Object[] array that grows by approximately 50% (1.5x) when capacity is exceeded, via the grow() method. This amortized cost of O(1) per add operation makes it efficient for dynamic resizing. In a real-world online store, inventory can grow unpredictably, and using ArrayList avoids manual array copying and index management, reducing bugs and maintenance overhead.
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.
TExam Day Tips
→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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Arrays and Methods — This question tests Arrays and Methods — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Modify the method to use an ArrayList<Product> internally and keep the signature. — Option A is correct because using an ArrayList<Product> internally allows the array to dynamically resize as needed, while keeping the method signature unchanged. The method still accepts a Product parameter, but the internal implementation leverages ArrayList's automatic capacity management, eliminating the fixed-size constraint.
What should I do if I get this 1Z0-811 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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