What modifiers may be used with an interface declaration

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An interface may be declared as public or abstract

In Core Java, an interface declaration can have the following modifiers:

  1. public: An interface can be declared as public, which means it can be accessed from other packages.
  2. abstract: Interfaces are implicitly abstract; you don’t need to use the abstract keyword explicitly. However, if you do use it, it won’t cause an issue.
  3. strictfp: This modifier is used to specify that the methods in the interface follow the strict floating-point format.

Therefore, the correct answer is: public and abstract.