- A
Use a FileReader wrapped in a BufferedReader, and process each line in a loop.
Why wrong: Although it reads line by line, it requires manual handling of the resource closure to avoid leaks. The approach is correct but less concise than using Files.lines with try-with-resources.
- B
Use a FileInputStream to read bytes, then manually parse newline characters.
Why wrong: FileInputStream reads raw bytes, requiring low-level parsing, which is more error-prone and less efficient for line-oriented processing.
- C
Use Files.readAllLines to read the entire file into a List<String> and then iterate.
Why wrong: Files.readAllLines loads the entire file into memory, which would cause OutOfMemoryError for a large file.
- D
Use Files.lines with a try-with-resources block, and process each line using the stream.
Files.lines returns a Stream that reads lines lazily, and try-with-resources ensures the underlying file handle is closed automatically. This is the most efficient and idiomatic solution.
Quick Answer
The correct choice is to use Files.lines with a try-with-resources block, processing each line via the stream. This approach leverages Java NIO2’s lazy loading: Files.lines returns a Stream<String> that reads lines on demand from the file, never holding the entire file in memory, which is essential for handling files several gigabytes in size. On the Oracle Certified Professional Java SE 17 Developer 1Z0-829 exam, this question tests your understanding of efficient I/O and resource management—a common trap is choosing Files.readAllLines, which loads everything into memory and risks OutOfMemoryError, or forgetting to close the stream, leading to resource leaks. The exam expects you to recognize that while a BufferedReader wrapped around a FileReader also reads line by line, Files.lines is more idiomatic and concise with its stream-based processing. Remember the mnemonic: “Lazy lines, try-with-resources, no memory crises.”
1Z0-829 Java I/O API and Securing Applications Practice Question
This 1Z0-829 practice question tests your understanding of java i/o api and securing applications. 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 developer needs to read a large text file (several gigabytes) line by line as efficiently as possible, processing each line without loading the entire file into memory. Which approach should the developer use?
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
Use Files.lines with a try-with-resources block, and process each line using the stream.
Files.lines returns a Stream<String> that reads lines lazily from the file, allowing processing without loading the whole file into memory. Using try-with-resources ensures the stream is closed properly. Option A (FileReader wrapped in BufferedReader) also reads line by line but requires manual resource management to avoid leaks; while correct, it is not the most idiomatic and concise approach. Option C (FileInputStream) reads raw bytes. Option D (Files.readAllLines) reads all lines into the memory, causing out-of-memory for large files.
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.
- ✗
Use a FileReader wrapped in a BufferedReader, and process each line in a loop.
Why it's wrong here
Although it reads line by line, it requires manual handling of the resource closure to avoid leaks. The approach is correct but less concise than using Files.lines with try-with-resources.
- ✗
Use a FileInputStream to read bytes, then manually parse newline characters.
Why it's wrong here
FileInputStream reads raw bytes, requiring low-level parsing, which is more error-prone and less efficient for line-oriented processing.
- ✗
Use Files.readAllLines to read the entire file into a List<String> and then iterate.
Why it's wrong here
Files.readAllLines loads the entire file into memory, which would cause OutOfMemoryError for a large file.
- ✓
Use Files.lines with a try-with-resources block, and process each line using the stream.
Why this is correct
Files.lines returns a Stream that reads lines lazily, and try-with-resources ensures the underlying file handle is closed automatically. This is the most efficient and idiomatic solution.
Related concept
Read the scenario before looking for a memorised answer.
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?
Java I/O API and Securing Applications — This question tests Java I/O API and Securing Applications — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use Files.lines with a try-with-resources block, and process each line using the stream. — Files.lines returns a Stream<String> that reads lines lazily from the file, allowing processing without loading the whole file into memory. Using try-with-resources ensures the stream is closed properly. Option A (FileReader wrapped in BufferedReader) also reads line by line but requires manual resource management to avoid leaks; while correct, it is not the most idiomatic and concise approach. Option C (FileInputStream) reads raw bytes. Option D (Files.readAllLines) reads all lines into the memory, causing out-of-memory for large files.
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 24, 2026
This 1Z0-829 practice question is part of Courseiva's free Oracle certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 1Z0-829 exam.
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