250+ TOP MCQs on Collection Framework Overview and Answers

Java MCQs on collection framework of Java Programming Language.

1. Which of these packages contain all the collection classes?
a) java.lang
b) java.util
c) java.net
d) java.awt

Answer: b

2. Which of these classes is not part of Java’s collection framework?
a) Maps
b) Array
c) Stack
d) Queue

Answer: a
Clarification: Maps is not a part of collection framework.

3. Which of this interface is not a part of Java’s collection framework?
a) List
b) Set
c) SortedMap
d) SortedList

Answer: d
Clarification: SortedList is not a part of collection framework.

4. Which of these methods deletes all the elements from invoking collection?
a) clear()
b) reset()
c) delete()
d) refresh()

Answer: a
Clarification: clear() method removes all the elements from invoking collection.

5. What is Collection in Java?
a) A group of objects
b) A group of classes
c) A group of interfaces
d) None of the mentioned

Answer: a
Clarification: A collection is a group of objects, it is similar to String Template Library (STL) of C++ programming language.

6. What will be the output of the following Java program?

  1.     import java.util.*;
  2.     class Array
  3.     {
  4.         public static void main(String args[])
  5.         {
  6.             int array[] = new int [5];
  7.             for (int i = 5; i > 0; i--)
  8.                 array[5-i] = i;
  9.             Arrays.fill(array, 1, 4, 8);
  10.             for (int i = 0; i < 5 ; i++)
  11.                 System.out.print(array[i]);
  12.         }
  13.     }

a) 12885
b) 12845
c) 58881
d) 54881

Answer: c
Clarification: array was containing 5,4,3,2,1 but when method Arrays.fill(array, 1, 4, 8) is called it fills the index location starting with 1 to 4 by value 8 hence array becomes 5,8,8,8,1.
Output:

$ javac Array.java
$ java Array
58881

7. What will be the output of the following Java program?

  1.     import java.util.*;
  2.     class Bitset
  3.     {
  4.         public static void main(String args[])
  5.         {
  6.             BitSet obj = new BitSet(5);
  7.             for (int i = 0; i < 5; ++i)
  8.                 obj.set(i);
  9.             obj.clear(2);
  10.             System.out.print(obj);
  11.         }
  12.     }

a) {0, 1, 3, 4}
b) {0, 1, 2, 4}
c) {0, 1, 2, 3, 4}
d) {0, 0, 0, 3, 4}

Answer: a
Clarification: None.
Output:

$ javac Bitset.java
$ java Bitset
{0, 1, 3, 4}

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