Java Map MCQs with answers Page - 6

You will find multiple-choice questions (MCQs) related to #Java Map here. Go through these questions to prepare effectively for your upcoming exams and interviews.

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Q. Which of the following methods is used to access all key-value mappings?

  • (A) entries()
  • (B) getAll()
  • (C) entrySet()
  • (D) mapAll()

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Q. Which Map allows only keys from a specific enum type?

  • (A) TreeMap
  • (B) EnumMap
  • (C) HashMap
  • (D) LinkedHashMap

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Q. Which of the following is a true statement about HashMap?

  • (A) It preserves key order
  • (B) It allows duplicate keys
  • (C) It is thread-safe
  • (D) It allows one null key

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Q. Which of the following is false for TreeMap?

  • (A) It maintains ascending order
  • (B) It allows null keys
  • (C) It implements SortedMap
  • (D) It is not synchronized

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Q. Which method is used to apply a function to all entries in a Map?

  • (A) forEach()
  • (B) map()
  • (C) applyAll()
  • (D) loop()

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Q. Which exception is thrown if null key is inserted in Hashtable?

  • (A) IllegalArgumentException
  • (B) NullPointerException
  • (C) UnsupportedOperationException
  • (D) IllegalStateException

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Q. Which Map should be used when high concurrency is needed?

  • (A) Hashtable
  • (B) HashMap
  • (C) TreeMap
  • (D) ConcurrentHashMap

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Q. Which is true about Map.of() method?

  • (A) Allows null keys
  • (B) Allows duplicate keys
  • (C) Immutable
  • (D) Thread-unsafe

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Q. Which of these Map implementations is ordered and thread-safe?

  • (A) TreeMap
  • (B) Collections.synchronizedMap(new LinkedHashMap<>())
  • (C) HashMap
  • (D) EnumMap

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Q. What does `Map.Entry` represent in Java?

  • (A) Only keys in a Map
  • (B) Only values in a Map
  • (C) A key-value pair in a Map
  • (D) An index in a Map

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