21. What is the unique feature of LinkedHashSet?

1. 1. The elements in the collection are linked to each other

   
   
   

   2. It provides a way to store key values with uniqueness

   
   
   

   3. It maintains the insertion order and guarantees uniqueness

   
   
   

   4. It is not a valid class

   
   
   

   5. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   Set is a collection of unique elements.HashSet has the behavior of Set and stores key value pairs. The LinkedHashSet stores the key value pairs in the order of insertion.

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22. Which of the below is not a subinterface of Queue?

1. 1. TransferQueue

   
   
   

   2. BlockingQueue

   
   
   

   3. BlockingQueue

   
   
   

   4. BlockingEnque

   
   
   

   5. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   BlockingQueue, TransferQueue and BlockingQueue are subinterfaces of Queue.

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23. What is the remaining capacity of BlockingQueue whose intrinsic capacity is not defined?

1. 1. Integer.INFINITY

   
   
   

   2. 99999999

   
   
   

   3. BigDecimal.MAX_VALUE

   
   
   

   4. Integer.MAX_VALUE

   
   
   

   5. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   A BlockingQueue without any intrinsic capacity constraints always reports a remaining capacity of Integer.MAX_VALUE.
   

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24. PriorityQueue is thread safe.

1. 1. Thread Safe

   
   
   

   2. true

   
   
   

   3. Not thread safe

   
   
   

   4. False

   
   
   

   5. A and B both

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: E

   PriorityQueue is not synchronized. BlockingPriorityQueue is the thread safe implementation.

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25. What is difference between dequeue() and peek() function of java?

1. 1. peek() removes and returns the next item in line while dequeue() returns the next item in line

   
   
   

   2. dequeue() removes and returns the next item in line while peek() returns the next item in line

   
   
   

   3. dequeue() and peek() return the next item in line

   
   
   

   4. dequeue() and peek() remove and return the next time in line

   
   
   

   5. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: B

   dequeue() removes the item next in line. peek() returns the item without removing it from the queue.

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