The correct practice is to write to a temporary file, then use Files.move() with the ATOMIC_MOVE option to replace the target file. This approach ensures crash-safe file writing because the atomic move operation guarantees that the target file is replaced only after the write to the temporary file succeeds; if the application crashes mid-write, only the temporary file is corrupted, leaving the original target file intact and preventing incomplete or partially written data from persisting. On the Oracle Certified Professional Java SE 17 Developer 1Z0-829 exam, this concept tests your understanding of file I/O atomicity and the java.nio.file package, often appearing in questions about data integrity and crash recovery. A common trap is assuming that renaming or copying directly to the target file is safe, but those operations are not atomic across the file system. Remember the mnemonic: “Write temp, then atomic move—crash leaves no groove.”
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 Java application writes sensitive user data to a file. To ensure that data is not left in the file system after the application crashes, which practice should be followed?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Write to a temporary file, then use Files.move() with ATOMIC_MOVE to replace the target file
Option D is correct because writing to a temporary file and then atomically moving it with `Files.move()` using the `ATOMIC_MOVE` option ensures that the target file is replaced only after the write succeeds. If the application crashes during the write, only the temporary file is corrupted, and the original target file remains intact. This prevents sensitive data from being left in an incomplete or partially written state in the file system.
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.
✗
Call flush() after every write operation
Why it's wrong here
Flush only ensures data is sent to the OS, but doesn't guarantee atomicity or cleanup on crash.
✗
Delete the file manually in a finally block
Why it's wrong here
If the JVM crashes abruptly, the finally block may not execute, leaving the file.
✗
Use a FileLock to prevent concurrent access
Why it's wrong here
FileLock prevents concurrent access but does not prevent data residue after a crash.
✓
Write to a temporary file, then use Files.move() with ATOMIC_MOVE to replace the target file
Why this is correct
Atomic move ensures the target file is either fully written or not replaced, preventing partial writes.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse data flushing or locking with crash-safe file updates, but neither `flush()` nor `FileLock` provides atomicity guarantees, which is the key requirement for preventing data corruption after a crash.
Detailed technical explanation
How to think about this question
The `ATOMIC_MOVE` option in `Files.move()` leverages the underlying file system's atomic rename operation (e.g., `rename()` on POSIX systems), which guarantees that the move is either fully completed or not performed at all, even in the event of a system crash. This pattern is commonly used in database transaction logs and configuration file updates to ensure write atomicity. A subtle behavior is that `ATOMIC_MOVE` may throw an `AtomicMoveNotSupportedException` if the source and target are on different file systems or the OS does not support atomic renames.
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 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 exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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: Write to a temporary file, then use Files.move() with ATOMIC_MOVE to replace the target file — Option D is correct because writing to a temporary file and then atomically moving it with `Files.move()` using the `ATOMIC_MOVE` option ensures that the target file is replaced only after the write succeeds. If the application crashes during the write, only the temporary file is corrupted, and the original target file remains intact. This prevents sensitive data from being left in an incomplete or partially written state in the file system.
What should I do if I get this 1Z0-829 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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