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Java Quiz Day 40
Question 1
Which method of HashMap is used to check if a key exists?
- A
containsKey()
- B
hasKey()
- C
keyExists()
- D
isKey()
Question 2
Which of the following is true about LinkedHashMap in Java?
- A
It does not maintain the insertion order
- B
It allows only unique values
- C
It maintains the insertion order
- D
It is slower than HashMap in terms of performance
Question 3
What is the time complexity of the get() method in a HashMap?
- A
O(log n)
- B
O(n)
- C
O(1)
- D
O(n^2)
Question 4
What does the TreeMap store in Java?
- A
Elements in random order
- B
Key-value pairs in ascending order of keys
- C
Only the keys, sorted
- D
Only the values, sorted
Question 5
Which of the following does NOT allow null keys in Java?
- A
HashMap
- B
TreeMap
- C
LinkedHashMap
- D
None of the above
Question 6
Which of the following is true about HashMap in Java?
- A
It does not maintain any order of keys
- B
It does not allow duplicate keys
- C
It allows null values and null keys
- D
All of the above
Question 7
Which Map implementation maintains the insertion order of keys?
- A
HashMap
- B
TreeMap
- C
LinkedHashMap
- D
EnumMap
Question 8
What happens when you insert a new entry with a key that already exists in a HashMap?
- A
The map throws an exception
- B
The existing value is replaced
- C
Both values are stored
- D
The new value is ignored
Question 9
Which Map implementation stores keys in sorted (natural) order?
- A
HashMap
- B
TreeMap
- C
LinkedHashMap
- D
IdentityHashMap
Question 10
Which of the following allows one null key and multiple null values?
- A
HashMap
- B
TreeMap
- C
LinkedHashMap
- D
Both a and c
There are 10 questions to complete.