Given the code fragment: abstract sealed interface Sint permits Story, Art { default String getTitle() { return "Book Title"; } } Which set of class definitions compiles?

Question

Options

• Ainterface Story extends Sint {} interface Art extends Sint {}
• Bpublic interface Story extends sind {} public interface Art extends Sint {}
• CSealed interface Story extends Sint {} Non-sealed class Art implements Sint {}
• DNon-sealed interface Story extends Sint {} Class Art implements Sint {}
• ENon-sealed interface Story extends Sint {} Non-sealed interface Art extends Sint {}

• A
  15% (9)
• B
  3% (2)
• C
  73% (43)
• D
  2% (1)
• E
  7% (4)

Explanation

Option C compiles because it correctly fulfills the sealed interface contract: sealed interface Story extends Sint {} uses the sealed modifier, and non-sealed class Art implements Sint {} uses non-sealed - every type listed in a permits clause must explicitly declare itself sealed, non-sealed, or final, and C is the only option that does this with valid Java syntax for both types.

Why the distractors fail:

• A - Both Story and Art are plain interfaces with no sealed/non-sealed modifier; permitted types cannot silently inherit from a sealed interface without declaring their own extensibility intent.
• B - Story incorrectly extends sind (lowercase typo), which doesn't exist; additionally, neither type has the required modifier.
• D - Class (capital C) is not a Java keyword; the correct keyword is class (lowercase), so Art won't compile.
• E - Non-sealed (capital N) is not a valid Java modifier; the correct keyword is non-sealed (all lowercase), making both declarations invalid.

Memory tip: "Every child of a sealed type must pick a lane" - sealed (keep restricting), non-sealed (open it back up), or final (dead end). No modifier = compile error, and keyword casing is exact in Java.

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