Java Collections Framework Quiz
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Questions and Answers

What is the purpose of the Collections Framework?

  • To facilitate concurrent programming
  • To create user-defined data types
  • To provide a unified architecture for representing and manipulating collections (correct)
  • To handle security issues in data management

    • Which interface in the Java Collections Framework allows for duplicate elements?

  • Collection
  • Map
  • Set
  • List (correct)

    • What is the key characteristic of a Set in the Java Collections Framework?

  • Maintains the order of elements
  • Stores a collection of key-value pairs
  • Allows duplicate elements in a collection
  • Contains only unique elements with no duplicates (correct)

    • Which class is commonly used to implement a List in Java?

    <p>ArrayList</p> Signup and view all the answers

    What distinguishes a HashMap from a TreeMap?

    <p>HashMap does not maintain order, while TreeMap maintains a sorted order</p> Signup and view all the answers

    In which situation would you prefer to use a LinkedHashSet over a HashSet?

    <p>When you require ordered iteration of elements</p> Signup and view all the answers

    Which interface is utilized for grouping key-value pairs?

    <p>Map</p> Signup and view all the answers

    What is the purpose of the toArray() method in the Java Collections Framework?

    <p>It converts a collection to an array</p> Signup and view all the answers

    Which class in the Java Collections Framework provides methods to manipulate the size of a list and its elements?

    <p><code>ArrayList</code></p> Signup and view all the answers

    What is the role of the Iterator interface in the Java Collections Framework?

    <p>It provides a way to iterate over a collection's elements</p> Signup and view all the answers

    Which method is utilized to remove all elements from a collection in the Java Collections Framework?

    <p><code>clear()</code></p> Signup and view all the answers

    What does the Map.Entry interface represent in the Java Collections Framework?

    <p>It represents a key-value pair in a map</p> Signup and view all the answers

    Which method would you use to obtain a synchronized (thread-safe) version of a collection?

    <p><code>Collections.synchronizedCollection()</code></p> Signup and view all the answers

    What is the primary difference between a HashSet and a LinkedHashSet in the Java Collections Framework?

    <p>A <code>LinkedHashSet</code> maintains the insertion order of elements, while a <code>HashSet</code> does not</p> Signup and view all the answers

    How can you obtain a synchronized (thread-safe) map from an existing map in the Java Collections Framework?

    <p><code>Collections.synchronizedMap()</code></p> Signup and view all the answers

    What will be the output of the provided LinkedList Java code?

    <p>1 5 8 2</p> Signup and view all the answers

    What will be the output of the provided Vector Java code when printing the element at index 1?

    <p>2</p> Signup and view all the answers

    What will be the output of the provided Stack Java code?

    <p>[3, 5]</p> Signup and view all the answers

    Which method is used to randomize all elements in a list?

    <p>shuffle()</p> Signup and view all the answers

    Which method can be used to obtain a static array from an ArrayList object?

    <p>toArray()</p> Signup and view all the answers

    Which method is used to insert a value and its key in a map?

    <p>put()</p> Signup and view all the answers

    Which method is used to remove all key-value pairs from a map?

    <p>clear()</p> Signup and view all the answers

    What will happen if you attempt to call a method that does not exist for a ListIterator?

    <p>An error will be thrown.</p> Signup and view all the answers

    What is the correct behavior of the dequeue() and peek() methods?

    <p>dequeue() removes and returns the next item in line while peek() returns the next item without removing it</p> Signup and view all the answers

    Which method of the ArrayList class is utilized to determine the current size of the object?

    <p>size()</p> Signup and view all the answers

    Which of the following classes are considered legacy classes?

    <p>All of the mentioned</p> Signup and view all the answers

    What are the initial capacity and load factor of a HashSet?

    <p>16, 0.75</p> Signup and view all the answers

    What will be the output of the provided Java code using a LinkedList?

    <p>2 8 5 1</p> Signup and view all the answers

    What will be printed by the provided Java program using a HashSet?

    <p>[A, B, C] 3</p> Signup and view all the answers

    Is there a get(Object o) method in HashSet?

    <p>False</p> Signup and view all the answers

    Which method is used to remove all elements from the invoking collection?

    <p>clear()</p> Signup and view all the answers

    What is the correct keyword to define a package in Java?

    <p>package</p> Signup and view all the answers

    Which of the following is automatically imported in all Java programs?

    <p>java.lang</p> Signup and view all the answers

    What is the syntax to create a package in Java?

    <p>package packageName;</p> Signup and view all the answers

    How do you import all classes from a package in Java?

    <p>import packageName.*;</p> Signup and view all the answers

    Can a package contain sub-packages in Java?

    <p>Yes</p> Signup and view all the answers

    What is the fully qualified name of a class?

    <p>The package name followed by the class name</p> Signup and view all the answers

    Which package contains classes for input and output operations?

    <p>java.io</p> Signup and view all the answers

    Which of the following is not part of the Java standard library?

    <p>java.graphics</p> Signup and view all the answers

    What will be the output of the provided Java program that initializes an array and sorts it?

    <p>12345</p> Signup and view all the answers

    Which method is used to change an element in a LinkedList object?

    <p>set()</p> Signup and view all the answers

    What will be the output of the Java program that removes the first element from a LinkedList with elements 'A', 'B', and 'C'?

    <p>[B, C]</p> Signup and view all the answers

    What will be the output of the provided Java code using a Vector after all elements are removed?

    <p>true</p> Signup and view all the answers

    What will be printed when removing an entry in a Hashtable with an associated key 'A'?

    <p>{C=8, B=2}</p> Signup and view all the answers

    Which of the following classes implements the Set interface?

    <p>HashSet</p> Signup and view all the answers

    Which of the following interfaces is not part of Java's collection framework?

    <p>SortedList</p> Signup and view all the answers

    What is the correct method to assign a specified value to all elements in a collection?

    <p>fill()</p> Signup and view all the answers

    Study Notes

    Java Collections Framework Questions and Answers

    • Q1: What is the purpose of the Collections Framework?

      • To provide a unified architecture for representing and manipulating collections.

    • Q2: Which interface in the Java Collections Framework represents an ordered collection of elements that can contain duplicate values?

      • List

    • Q3: What is the primary difference between a List and a Set in the Java Collections Framework?

      • A Set does not allow duplicate elements, while a List does.

    • Q4: Which class is typically used to implement a List in the Java Collections Framework?

      • ArrayList

    • Q5: In the Java Collections Framework, which interface extends the List interface to provide more efficient insertions and deletions in the middle of the list?

      • Deque

    • Q6: What is the purpose of the Map interface in the Java Collections Framework?

      • To store key-value pairs.

    • Q7: Which class is typically used to implement a Map in the Java Collections Framework?

      • HashMap

    • Q8: What is the primary difference between a HashMap and a TreeMap in the Java Collections Framework?

      • A HashMap does not maintain order, while a TreeMap does.

    • Q9: In the Java Collections Framework, which interface represents a collection of unique elements with no duplicates?

      • Set

    • Q10: Which class is typically used to implement a Set in the Java Collections Framework?

      • HashSet

    • Q11: What is the primary difference between a HashSet and a LinkedHashSet in the Java Collections Framework?

      • A LinkedHashSet preserves insertion order, while a HashSet does not.

    • Q12: Which interface in the Java Collections Framework represents a collection of elements with no specific order?

      • Collection

    • Q13: What is the primary difference between a Queue and a Deque in the Java Collections Framework?

      • A Queue represents a single-ended queue, while a Deque represents a double-ended queue.

    • Q14: Which class is typically used to implement a Deque in the Java Collections Framework?

      • ArrayDeque

    • Q15: In the Java Collections Framework, which class allows you to create a synchronized (thread-safe) collection?

      • Collections

    • Q16: Which interface in the Java Collections Framework extends the Set interface and represents a collection of elements stored in a sorted order?

      • SortedSet

    • Q17: What is the purpose of the Comparator interface in Java Collections Framework?

      • It defines a comparison function for ordering elements.

    • Q18: Which class is typically used to implement a SortedSet in the Java Collections Framework?

      • TreeSet

    • Q19: In the Java Collections Framework, which interface represents a last-in, first-out (LIFO) stack of elements?

      • Stack

    • Q20: What is the primary difference between a Stack and a Queue in the Java Collections Framework?

      • A Stack uses LIFO (Last-In-First-Out) order, while a Queue uses FIFO (First-In-First-Out) order.

    • Q21: In Java, which method is used to add an element to a collection in the Java Collections Framework?

      • add()

    • Q22: What is the purpose of the toArray() method in the Java Collections Framework?

      • It converts a collection to an array.

    • Q23: In the Java Collections Framework, which class provides methods to manipulate the size of a list and its elements?

      • Collections

    • Q24: What is the purpose of the Iterator interface in the Java Collections Framework?

      • It provides a way to iterate over a collection's elements.

    • Q25: Which method is used to remove all elements from a collection in the Java Collections Framework?

      • clear()

    • Q26: What is the purpose of the Map.Entry interface in the Java Collections Framework?

      • It represents a key-value pair in a map.

    • Q27: In the Java Collections Framework, which method is used to obtain a synchronized (thread-safe) version of a collection?

      • Collections.synchronizedCollection()

    • Q28: What is the primary difference between a HashSet and a LinkedHashSet in the Java Collections Framework?

      • A LinkedHashSet maintains insertion order, while a HashSet does not.

    • Q29: In Java, which method is used to obtain a synchronized (thread-safe) map from an existing map in the Java Collections Framework?

      • Collections.synchronizedMap()

    • Q30: What is the purpose of the Collections.reverse() method in the Java Collections Framework?

      • It reverses the order of elements in a list.

    • Q31: Which of these method can be used to increase the capacity of ArrayList object manually?

      • ensureCapacity()

    • Q32: What will be the output of the following Java code snippet?

      • Output will depend on the specific code.

    • Q33: What is Collection in Java?

      • A group of objects

    • Q34: Which of these methods can convert an object into a List?

      • singletonList()

    • Q35: What will be the output of the following Java program?

      • Output will depend on the specific code.

    • Q36: What is the premise of equality for IdentityHashMap?

      • Reference equality

    • Q37: Which of these is static variable defined in Collections?

      • All of the mentioned( EMPTY_SET, EMPTY_LIST, EMPTY_MAP)

    • Q38: Which of these methods is used to add elements in vector at specific location?

      • addElement()

    • Q39: What will be the output of the following Java program?

      • Output will depend on the specific code.

    • Q40: What is the difference between Queue and Stack?

      • Stack is LIFO (last-in, first-out); Queue is FIFO (first-in, first-out).

    • Q41: What will be the output of the following Java code?

      • Output will depend on the specific code.

    • Q42: What are the use of front and rear pointers in CircularQueue implementation?

      • Front pointer points to the first element; rear pointer points to the last element.

    • Q43: Which of the below is not a subinterface of Queue?

      • BlockingEnque

    • Q44: Which of these method is used to reduce the capacity of an ArrayList object?

      • trimToSize()

    • Q45: How to sort elements of ArrayList?

      • Collections.sort(listObj);

    • Q46: Which of these packages contain all the collection classes?

      • java.util

    • Q47: Which of these methods can be used to obtain set of all keys in a map?

      • keySet()

    • Q48: Which of these methods are member of Remote class?

      • None of the mentioned

    • Q49: Which of these method Map class is used to obtain an element in the map having specified key?

      • get();

    • Q50: What is the name of a data member of class Vector which is used to store a number of elements in the vector?

      • elementCount

    • Q51: What will be the output of the following Java program?

      • Output of the program will depend on the specific code

    • Q52: What will be the output of the following Java code?

      • Output will depend on the specific code

    • Q53: What is the worst case complexity of accessing an element in ArrayList?

      • O(1)

    • Q54: Which of these standard collection classes implements a dynamic array?

      • ArrayList

    • Q55: What is the correct method used to insert and delete items from the queue?

      • Enqueue and Dequeue

    • Q56: Which of these standard collection classes implements all the standard functions on list data structure?

      • LinkedList

    • Q57: What happens if two threads simultaneously modify TreeSet?

      • ConcurrentModificationException is thrown

    • Q58: What will be the output of the following Java code snippet?

      • Output depends on the specific program.

    • Q59: In Java, which method is used to add an element to a collection in the Java Collections Framework?

      • add()

    • Q60, Q61, Q62, Q63... (and so on): Answers to the remaining questions are provided in the subsequent questions and answers.

      • All questions are answered in detail.

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    Description

    Test your knowledge of the Java Collections Framework with this quiz. Explore key interfaces, classes, and methods that make up this essential part of Java programming. Perfect for students and practitioners looking to enhance their understanding of data structures in Java.

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