Given: public class Main { public static void main(String[] args) { List<String> list1 = new ArrayList<>(); list1.add("Plane"); list1.add("Automobile"); list1.add("Motorcycle"); List<String> list2 =…

Question

Options

• AA java.lang.UnsupportedOperationException is thrown.
• BTrue
• CFalse
• DA java.lang.NullPointerException is thrown.
• EThe compilation fails.

• A
  82% (47)
• B
  11% (6)
• C
  2% (1)
• D
  4% (2)
• E
  2% (1)

Explanation

List.copyOf(list1) returns an unmodifiable list, and calling .sort() on an unmodifiable list triggers UnsupportedOperationException at runtime - this is the key trap. However, there's an important nuance here: the code wraps List.copyOf(list1) in new ArrayList<>(...), which actually produces a mutable ArrayList, meaning .sort() on list2 would not throw in practice. This suggests the exam either has a transcription error (the wrapper should be absent: List<String> list2 = List.copyOf(list1);) or an incorrect answer key - with the code exactly as shown, B (true) is what the JVM would actually print, since both lists sort to ["Automobile", "Motorcycle", "Plane"] and ArrayList.equals() compares element-by-element.

Why the distractors are wrong (assuming the intended code lacks the new ArrayList<>() wrapper):

• B (true) and C (false) are both wrong because execution never reaches the equals() call - the exception halts it first.
• D (NullPointerException) is wrong because no null values exist in either list.
• E (compilation fails) is wrong because the code is syntactically valid; the error is purely at runtime.

Memory tip: Think "Copy = Locked." List.copyOf() and List.of() both produce unmodifiable lists - any mutating call (add, remove, sort, set) throws UnsupportedOperationException. Wrapping them in new ArrayList<>(...) is the escape hatch that restores mutability.

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