, B, and C describe syntax issues that are not the primary cause here.","domainId":"4a26bb63-b39d-4130-b392-6b8709b164ec","difficulty":"easy","questionType":"multiple_choice","pbqConfig":null,"exhibitText":"Refer to the exhibit.\n\n```\nError: incompatible types: bad type in switch expression\n return switch(day) {\n ^\n required: int\n found: String\n```","options":[{"id":"3aa36a2c-4b87-4ea2-9a7e-9cb9cd3bbbd9","label":null,"text":"The switch expression uses arrow syntax but the keys are not unique.","isCorrect":false},{"id":"96ce9658-215a-41d4-b6db-349277174d8b","label":null,"text":"The switch expression is missing a default case.","isCorrect":false},{"id":"c4afb536-eb7c-49d9-9fe3-f7ef7d7dd7b7","label":null,"text":"The switch expression is not assigned to a variable.","isCorrect":false},{"id":"7f5db362-f1a1-4e74-a2bc-077ae5b1dc8b","label":null,"text":"The switch selector is a String but case labels are int constants.","isCorrect":true}],"domainName":"Controlling Program Flow","domainSlug":"program-flow"},{"id":"a98d9967-6b1c-477a-b0a9-7b714c1725a2","slug":"a-method-returns-a-list-integer-the-caller-wants-to-ensure-lwr3m","questionText":"A method returns a List. The caller wants to ensure the list cannot be modified. Which is the best approach?","explanation":"`Collections.unmodifiableList()` returns a read-only view of the specified list. Any attempt to modify the returned list (e.g., via `add`, `remove`, `set`) will throw an `UnsupportedOperationException`. This is the standard, recommended approach in the Java Collections Framework to provide an unmodifiable wrapper without copying the underlying data.","domainId":"b7c87695-2168-4565-a967-300d847a5d54","difficulty":"medium","questionType":"multiple_choice","pbqConfig":null,"exhibitText":null,"options":[{"id":"a881d721-ffed-4a4d-9e46-f7ed823a16b6","label":null,"text":"return Arrays.asList(list.toArray());","isCorrect":false},{"id":"f0dcddf8-7ab2-42f9-b2f4-8fcc507bd277","label":null,"text":"return new ArrayList<>(list);","isCorrect":false},{"id":"b961e40f-a42a-44fc-8c5e-4f2c70d81109","label":null,"text":"return (List) list.clone();","isCorrect":false},{"id":"9844dfb8-ca69-4d24-a1b8-6ac14e9d7777","label":null,"text":"return Collections.unmodifiableList(list);","isCorrect":true}],"domainName":"Working with Arrays and Collections","domainSlug":"arrays-collections"},{"id":"927b9f15-780e-468f-9c9a-987c24b3b17a","slug":"a-lambda-that-takes-a-string-and-returns-its-length-is-assig-wo80x","questionText":"A lambda that takes a String and returns its length is assigned to which functional interface?","explanation":"The lambda `(String s) -> s.length()` takes a `String` input and returns an `Integer` (the length). This matches the `Function` functional interface, which defines the abstract method `R apply(T t)`. Option E is correct because `Function` exactly represents a function that accepts a `String` and produces an `Integer`.","domainId":"b5e6056f-afa9-4785-88a4-82ede285131f","difficulty":"easy","questionType":"multiple_choice","pbqConfig":null,"exhibitText":null,"options":[{"id":"3ad4fecb-523a-411b-9f5d-1c7fbd9e1883","label":null,"text":"UnaryOperator","isCorrect":false},{"id":"399d8dd7-0c21-46ad-9946-ef570236a95a","label":null,"text":"Consumer","isCorrect":false},{"id":"6e645bb9-837b-4f5e-a3bf-dcbc0c9ef223","label":null,"text":"Predicate","isCorrect":false},{"id":"823183de-7aed-4be0-8bda-84ff0242f194","label":null,"text":"Supplier","isCorrect":false},{"id":"2908209c-d467-4972-9c02-f680803edd71","label":null,"text":"Function","isCorrect":true}],"domainName":"Working with Streams and Lambda Expressions","domainSlug":"streams-lambdas"},{"id":"55cbc0e7-0ff3-4c73-a6cd-38808672b03e","slug":"a-developer-wants-to-traverse-a-directory-tree-to-find-all-f-rgk8v","questionText":"A developer wants to traverse a directory tree to find all files that are symbolic links. Which NIO.2 method should be used to follow symbolic links during traversal?","explanation":"`Files.

Exhibit