Java Map MCQs with answers Page - 5

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 method in the Map interface is used to return the value if present, or else compute it?

  • (A) computeIfPresent()
  • (B) getOrDefault()
  • (C) computeIfAbsent()
  • (D) mapOrElse()

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Q. Which Map implementation uses the least memory for enum keys?

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

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Q. Which method is used to check if a Map is empty?

  • (A) isEmpty()
  • (B) empty()
  • (C) hasNoValues()
  • (D) checkEmpty()

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Q. What does the `putIfAbsent()` method do?

  • (A) Adds a new entry regardless of presence
  • (B) Replaces old value
  • (C) Adds only if key is absent
  • (D) Throws an exception if key exists

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Q. Which interface does TreeMap implement apart from Map?

  • (A) Queue
  • (B) SortedMap
  • (C) List
  • (D) SortedSet

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Q. Which method in Map replaces all values based on a function?

  • (A) forEach()
  • (B) replaceAll()
  • (C) mapValues()
  • (D) setAll()

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Q. How can you create an immutable Map in Java 9?

  • (A) new HashMap<>()
  • (B) Map.of()
  • (C) Collections.unmodifiableMap()
  • (D) Map.emptyMap()

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Q. What is the time complexity for insertion in HashMap?

  • (A) O(n)
  • (B) O(1)
  • (C) O(log n)
  • (D) O(n log n)

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Q. What happens when you call clear() on a Map?

  • (A) It deletes only keys
  • (B) It deletes only values
  • (C) It deletes all entries
  • (D) Nothing happens

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Q. Which class is best suited when Map order needs to be preserved and fast iteration is needed?

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

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