Java Questions & Answers – Java.util – Array Class

This section of our 1000+ Java MCQs focuses on Array class under java.util library of Java Programming Language.

1. Which of these standard collection classes implements all the standard functions on list data structure?
a) Array
b) LinkedList
c) HashSet
d) AbstractSet
View Answer

Answer: a
Explanation: None.

2. Which of this method is used to make all elements of an equal to specified value?
a) add()
b) fill()
c) all()
d) set()
View Answer

Answer: b
Explanation: fill() method assigns a value to all the elements in an array, in other words, it fills the array with specified value.

3. Which of these method of Array class is used sort an array or its subset?
a) binarysort()
b) bubblesort()
c) sort()
d) insert()
View Answer

Answer: c
Explanation: None.
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4. Which of these methods can be used to search an element in a list?
a) find()
b) sort()
c) get()
d) binaryserach()
View Answer

Answer: d
Explanation: binaryserach() method uses binary search to find a specified value. This method must be applied to sorted arrays.

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

  1.     import java.util.*;
  2.     class Arraylist 
  3.     {
  4.         public static void main(String args[])
  5.         {
  6.             ArrayList obj1 = new ArrayList();
  7.             ArrayList obj2 = new ArrayList();
  8.             obj1.add("A");
  9.             obj1.add("B");
  10.             obj2.add("A");
  11.             obj2.add(1, "B");
  12.             System.out.println(obj1.equals(obj2));
  13.         }
  14.     }

a) 0
b) 1
c) true
d) false
View Answer

Answer: c
Explanation: obj1 and obj2 are an object of class ArrayList hence it is a dynamic array which can increase and decrease its size. obj.add(“X”) adds to the array element X and obj.add(1,”X”) adds element x at index position 1 in the list, Both the objects obj1 and obj2 contain same elements i:e A & B thus obj1.equals(obj2) method returns true.
Output:

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$ javac Arraylist.java
$ java Arraylist
true

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

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  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.sort(array);
  10.             for (int i = 0; i < 5; ++i)
  11.             	System.out.print(array[i]);;
  12.         }
  13.     }

a) 12345
b) 54321
c) 1234
d) 5432
View Answer

Answer: a
Explanation: Arrays.sort(array) method sorts the array into 1,2,3,4,5.
Output:

$ javac Array.java
$ java Array
12345

7. 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.sort(array);
  10.             System.out.print(Arrays.binarySearch(array, 4));
  11.         }
  12.     }

a) 2
b) 3
c) 4
d) 5
View Answer

Answer: b
Explanation: None.
Output:

$ javac Array.java
$ java Array
3

Sanfoundry Global Education & Learning Series – Java Programming Language.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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