Question 501 of 513
1Z0-829 Java I/O API and Securing Applications Practice Question
A developer needs to read all lines from a text file named "data.txt" that uses UTF-8 encoding. Which code correctly reads the file using the NIO.2 API?
⚠ Common exam trap
Many candidates confuse `Files.readString()` (which returns a single string) with `Files.readAllLines()` (which returns a list of lines), or they mistakenly think `Files.readAllBytes().toString()` will convert bytes to text, when in fact it returns the object reference string.
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
✓
Files.readAllLines(Path.of("data.txt"), StandardCharsets.UTF_8)
`Files.readAllLines()` reads all lines from a file into a `List<String>`, and it accepts a `Path` and a `Charset` (here `StandardCharsets.UTF_8`) to handle encoding. This method is part of the NIO.2 API and directly fulfills the requirement to read all lines from a UTF-8 encoded file.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Files.lines(Path.of("data.txt"), StandardCharsets.UTF_8).collect(Collectors.toList())
Why it's wrong here
This reads lines into a Stream and collects to a list, but it's less efficient and not the direct method for reading all lines.
- ✗
Files.readString(Path.of("data.txt"), StandardCharsets.UTF_8)
Why it's wrong here
Files.readString reads the entire file into a single String, not a list of lines.
- ✗
Files.readAllBytes(Path.of("data.txt")).toString()
Why it's wrong here
Files.readAllBytes returns a byte array, and calling toString() does not decode lines properly.
- ✓
Files.readAllLines(Path.of("data.txt"), StandardCharsets.UTF_8)
Why this is correct
Files.readAllLines directly returns a List<String> with the specified charset, which is the simplest correct approach.
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Last reviewed: Jun 25, 2026
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