Question on Arrays
Question on Arrays
1. Which of these operators is used to allocate memory to
array variable in Java?
a) malloc
b) alloc
c) new
d) new malloc
Answer: c
Explanation: Operator new allocates a block of memory
specified by the size of an array, and gives the reference of memory allocated
to the array variable.
2. Which of these is an incorrect array declaration?
a) int arr[] = new int[5].
b) int [] arr = new int[5].
c) int arr[] = new int[5].
d) int arr[] = int [5] new
Answer: d
Explanation: Operator new must be succeeded by array type
and array size.
3. What will this code print?
int arr[] = new
int [5];
System.out.print(arr);
a) 0
b) value stored in arr[0].
c) 00000
d) Class name@ hashcode in hexadecimal form
Answer: d
Explanation: If we trying to print any reference variable
internally, toString() will be called which is implemented to return the String
in following form:
classname@hashcode in hexadecimal form
4. Which of these is an incorrect Statement?
a) It is necessary to use new operator to initialize an
array
b) Array can be initialized using comma separated
expressions surrounded by curly braces
c) Array can be initialized when they are declared
d) None of the mentioned
Answer: a
Explanation: Array can be initialized using both new and
comma separated expressions surrounded by curly braces example : int arr[5] =
new int[5]; and int arr[] = { 0, 1, 2, 3, 4};
5. Which of these is necessary to specify at time of
array initialization?
a) Row
b) Column
c) Both Row and Column
d) None of the mentioned
Answer: a
Explanation: None.
6. What is the output of this program?
class
array_output
{
public
static void main(String args[])
{
int
array_variable [] = new int[10];
for (int i = 0; i < 10; ++i)
{
array_variable[i] = i;
System.out.print(array_variable[i] + " ");
i++;
}
}
}
a) 0 2 4 6 8
b) 1 3 5 7 9
c) 0 1 2 3 4 5 6 7 8 9
d) 1 2 3 4 5 6 7 8 9 10
Answer: a
Explanation: When an array is declared using new operator
then all of its elements are initialized to 0 automatically. for loop body is
executed 5 times as whenever controls comes in the loop i value is incremented
twice, first by i++ in body of loop then by ++i in increment condition of for
loop.
output:
$ javac array_output.java
$ java array_output
0 2 4 6 8
7. What is the output of this program?
class
multidimention_array
{
public
static void main(String args[])
{
int
arr[][] = new int[3][];
arr[0]
= new int[1];
arr[1]
= new int[2];
arr[2]
= new int[3];
int sum = 0;
for (int i = 0; i < 3; ++i)
for (int j = 0; j < i + 1; ++j)
arr[i][j] = j + 1;
for (int i = 0; i < 3; ++i)
for (int j = 0; j < i + 1; ++j)
sum + = arr[i][j];
System.out.print(sum);
}
}
a) 11
b) 10
c) 13
d) 14
Answer: b
Explanation: arr[][] is a 2D array, array has been
allotted memory in parts. 1st row contains 1 element, 2nd row contains 2
elements and 3rd row contains 3 elements. each element of array is given i + j
value in loop. sum contains addition of all the elements of the array.
output:
$ javac multidimention_array.java
$ java multidimention_array
10
8. What is the output of this program?
class evaluate
{
public
static void main(String args[])
{
int arr[] = new int[] {0 , 1, 2, 3, 4,
5, 6, 7, 8, 9};
int n = 6;
n =
arr[arr[n] / 2];
System.out.println(arr[n] / 2);
}
}
a) 3
b) 0
c) 6
d) 1
Answer: d
Explanation: Array arr contains 10 elements. n contains 6
thus in next line n is given value 2 printing arr[2]/2 i:e 2/2 = 1.
output:
$ javac evaluate.java
$ java evaluate
1
9. What is the output of this program?
class
array_output
{
public
static void main(String args[])
{
char
array_variable [] = new char[10];
for (int i = 0; i < 10; ++i)
{
array_variable[i] = 'i';
System.out.print(array_variable[i] + "");
}
}
}
a) 1 2 3 4 5 6 7 8 9 10
b) 0 1 2 3 4 5 6 7 8 9 10
c) i j k l m n o p q r
d) i i i i i i i i i i
Answer: d
Explanation: None.
output:
$ javac array_output.java
$ java array_output
i i i i i i i i i i
10. What is the output of this program?
class
array_output
{
public
static void main(String args[])
{
int
array_variable[][] = {{ 1, 2, 3}, { 4 , 5, 6}, { 7, 8, 9}};
int sum
= 0;
for
(int i = 0; i < 3; ++i)
for
(int j = 0; j < 3 ; ++j)
sum = sum + array_variable[i][j];
System.out.print(sum / 5);
}
}
a) 8
b) 9
c) 10
d) 11
Answer: b
Explanation: None.
output:
$ javac array_output.java
$ java array_output
9
11. What is the type of variable ‘b’ and ‘d’ in the below
snippet?
int a[], b;
int []c, d;
a) ‘b’ and ‘d’ are int
b) ‘b’ and ‘d’ are arrays of type int
c) ‘b’ is int variable; ‘d’ is int array
d) ‘d’ is int variable; ‘b’ is int array
Answer: c
Explanation: If [] is declared after variable it is
applicable only to one variable. If [] is declared before variable it is
applicable to all the variables.
12. Which of these is an incorrect array declaration?
a) int arr[] = new int[5] ;
b) int [] arr = new int[5] ;
c)
int arr[];
arr = new int[5];
d) int arr[] = int [5] new;
Answer: d
Explanation: Operator new must be succeeded by array type
and array size. The order is important and determines the type of variable.
13. What will this code print?
int arr[] = new int [5];
System.out.print(arr);
a) 0
b) value stored in arr[0].
c) 00000
d) Garbage value
Answer: d
Explanation: arr is an array variable, it is pointing to
array of integers. Printing arr will print garbage value. It is not same as
printing arr[0].
14. What is the output of below snippet?
Object[] names = new String[3];
names[0] = new Integer(0);
a) ArrayIndexOutOfBoundsException
b) ArrayStoreException
c) Compilation Error
d) Code runs successfully
Answer: b
Explanation: ArrayIndexOutOfBoundsException comes when
code tries to access an invalid index for a given array. ArrayStoreException
comes when you have stored an element of type other than the type of array.
15. Generics does not work with?
a) Set
b) List
c) Tree
d) Array
Answer: d
Explanation: Generics gives the flexibility to strongly
typecast collections. Generics is applicable to Set, List and Tree. It is not
applicable to Array.
16. How to sort an array?
a) Array.sort()
b) Arrays.sort()
c) Collection.sort()
d) System.sort()
Answer: b
Explanation: Arrays class contains various methods for
manipulating arrays (such as sorting and searching). Array is not a valid
class.
17. How to copy contents of array?
a) System.arrayCopy()
b) Array.copy()
c) Arrays.copy()
d) Collection.copy()
Answer: a
Explanation: Arrays class contains various methods for
manipulating arrays (such as sorting and searching). Array is not a valid
class.
18. Can you make an array volatile?
a) True
b) False
Answer: a
Explanation: You can only make variable pointing to array
volatile. If an array is changed by replacing individual elements then
guarantee provided by volatile variable will not be held.
19. Where is array stored in memory?
a) heap space
b) stack space
c) heap space and stack space
d) first generation memory
Answer: a
Explanation: Array is stored in heap space. Whenever an
object is created, it’s always stored in the Heap space and stack memory
contains the reference to it.
20. An array elements are always stored in ________
memory locations?
a) Sequential
b) Random
c) Sequential and Random
d) Binary search
Answer: a
Explanation: Array elements are stored in contiguous memory.
Linked List is stored in random memory locations.
Question on Arrays
Reviewed by Unknown
on
February 24, 2019
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Reviewed by Unknown
on
February 24, 2019
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