Multiple Choice Questions on JAVA (object oriented programming) bank 3 -- class,objects,conditional statements

MCQs BANK
Page: 1
Object Oriented
Programming
Topic: Class,Objects,
Conditional Statements
Instructions:
This MCQs Bank contains question
and solution on adjacent(even-odd)
pages. First try to solve the MCQ by
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MCQs BANK No.: 3

MCQs Bank on Object Oriented Programming
Topic: Class,Objects,Conditional Statements
MCQ No: 1
A _______ is the blueprint from
which individual objects are
created. Fill in the blank.
a) class
b) object
c) instance
d) structure
Page: 2

MCQ No: 1 (Solution)
Ans: a) class
Explanation:
A class is the blueprint from which
individual objects are created. In
object-oriented terms, we say that
the object you create is an
instance of the class of objects.
Page: 3

MCQ No: 2
Fill in the following blanks:-
Member variables in a class—these are
called _________ .
Variables in a method or block of
code—these are called ___________ .
Variables in method declarations—
these are called __________.
a) parameters, fields, local variables
b) fields, local variables, parameters
c) local variables, parameters, fields
d) parameters, local variables, fields
Page: 4

Ans: b) fields, local variables,
parameters
Explanation:
Member variables in a class—
these are called fields.
Variables in a method or block of
code—these are called local
variables.
Variables in method declarations—
these are called parameters.
Page: 5

MCQ No: 3
The ________ keyword is a Java
operator that creates the object. Fill
in the blank.
a) const
b) new
c) static
d) import
Page: 6

Ans: b) new
Explanation: The new keyword is a
Java operator that creates the
object. The new operator is followed
by a call to a constructor, which
initializes the new object. Example:
Bicycle bike1 = new Bicycle(); it
creates an object of the Bicycle
class.
The new operator instantiates a
class by allocating memory for a
new object and returning a
reference to that memory. The
new operator also invokes the
object constructor.
Page: 7

MCQ No: 4
The phrase "instantiating a class"
means the same thing as
______________ . Fill in the blank.
a) "creating an class."
b) "declaring a reference."
c) "creating an object."
d) "rename an object."
Page: 8

Ans: c) "creating an object."
Explanation:
The phrase "instantiating a class"
means the same thing as "creating
an object." When you create an
object, you are creating an
"instance" of a class, therefore
"instantiating" a class.
If you declare a reference like this:
class ref; the value of "ref" will be
undetermined until an object is
actually created and assigned to it.
Simply declaring a reference variable
does not create an object.
Page: 9

MCQ No: 5
A _________ can be recognized
easily, because its declaration
uses the same name as the class
and it has no return type. Fill in the
blank.
a) method
b) constructor
c) destructor
d) reference
Page: 10

Ans: b) constructor
Explanation: Consider the following
class:-
This class contains a single
constructor. You can recognize a
constructor because its declaration
uses the same name as the class
and it has no return type.
Page: 11

MCQ No: 6
If a class has multiple constructors,
they must have different
signatures. True or False
a) True
b) False
Page: 12

Ans: a) True
Explanation:
If a class has multiple constructors,
they must have different signatures.
The Java compiler differentiates the
constructors based on the number
and the type of the arguments.
Page: 13

MCQ No: 7
All classes have at least one
constructor. If a class does not
explicitly declare any, the Java
compiler automatically provides
a no-argument constructor, called
the default constructor. True or
False
a) True
b) False
Page: 14

Ans: a) True
Explanation:
All classes have at least one
constructor. If a class does not
explicitly declare any, the Java
compiler automatically provides
a no-argument constructor, called
the default constructor. This default
constructor calls the class parent's
no-argument constructor, or the
Object constructor if the class has
no other parent. If the parent has no
constructor (Object does have
one), the compiler will reject the
program.
Page: 15

MCQ No: 8
The data type of the value returned
by the method,( or void if the
method does not return a value) is
called ________. Fill in the blank.
a) return type
b) method name
c) parameters list
d) method signature
Page: 16

Ans: a) return type
Explanation: The return type—the data
type of the value returned by the method,
or void if the method does not return a
value.
The parameter list in parenthesis—a
comma-delimited list of input parameters,
preceded by their data types, enclosed by
parentheses, (). If there are no
parameters, you must use empty
parentheses.
Two of the components of a method
declaration comprise the method
signature—the method's name and the
parameter types. Example:
calculateAnswer(double, int, double,
double)
Page: 17

MCQ No: 9
Typically, a method has a unique
name within its class. However, a
method might have the same name
as other methods due to
_________ . Fill in the blank.
a) method overriding
b) method overloading
c) both (a) and (b)
d) lack of new method name
Page: 18

Ans: c) both (a) and (b)
Explanation: Typically, a method
has a unique name within its class.
However, a method might have the
same name as other methods
due to method overloading.
If a subclass provides the specific
implementation of the method that
has been declared by one of its
parent class, it is known as method
overriding.
Page: 19

MCQ No: 10
The Java programming language
supports overloading methods, and
Java can distinguish between
methods with different
_____________ . Fill in the blank.
a) method return type
b) method names
c) method signatures
d) method body
Page: 20

Ans: c) method signatures
Explanation: The Java language
supports overloading methods, and Java
can distinguish between methods with
different method signatures. This means
that methods within a class can have the
same name if they have different
parameter lists. Overloaded methods are
differentiated by the number and the type
of the arguments passed into the method.
You cannot declare more than one method
with the same name and the same number
and type of arguments, because the
compiler cannot tell them apart. The
compiler does not consider return type
when differentiating methods, so you
cannot declare two methods with the same
signature even if they have a different
return type.
Page: 21

MCQ No: 11
A _________ is a special method
that is used to initialize a newly
created object and is called just
after the memory is allocated for
the object. It can be used to
initialize the objects ,to required ,or
default values at the time of object
creation.
a) destructor
b) new
c) constructor
d) static
Page: 22

Ans: c) constructor
Explanation:
A constructor is a special method
that is used to initialize a newly
created object and is called just after
the memory is allocated for the
object. It can be used to initialize the
objects ,to required ,or default values
at the time of object creation. It is not
mandatory for the coder to write a
constructor for the class. If no user
defined constructor is provided for a
class, compiler initializes member
variables to its default values.
Page: 23

MCQ No: 12
In order to create a Constructor
observe the following rules
1. It has the same name as the
class
2. It should not return a value not
even void
a) Both rules are TRUE
b) Only the rule 1 is TRUE
c) Only the rule 2 is TRUE
d) Both rules are FALSE
Page: 24

Ans: a) Both rules are TRUE
Explanation:
In order to create a Constructor
observe the following rules
1. It has the same name as the class
2. It should not return a value not
even void
If no user defined constructor is
provided for a class, compiler
initializes member variables to its
default values.
Page: 25

MCQ No: 13
Constructor overloading is a
technique in Java in which a class
can have any number of
constructors that differ in
_____________. Fill in the blank.
a) return type
b) parameter lists
c) constructor body
d) constructor name
Page: 26

Ans: b) parameter lists
Explanation:
Constructor overloading is a
technique in Java in which a class
can have any number of constructors
that differ in parameter lists. The
compiler differentiates these
constructors by taking into account
the number of parameters in the list
and their type.
Examples of valid constructors for
class Account are
Account(int a);
Account (int a,int b);
Account (String a,int b);
Page: 27

MCQ No: 14
Java allows you to control access
to classes, methods, and fields via
so-called __________. Fill in the
blank.
a) encapsulation
b) constructors
c) access specifiers
d) polymorphism
Page: 28

Ans: c) access specifiers
Explanation:
One of the techniques in object-oriented
programming is encapsulation. It
concerns the hiding of data in a class and
making this class available only through
methods. In this way the chance of
making accidental mistakes in changing
values is minimized. Java allows you to
control access to classes, methods, and
fields via so-called access specifiers.
Java offers four access specifiers, listed
below in decreasing accessibility:
• public
• protected
• default (no specifier)
• private
Page: 29

MCQ No: 15
__________ classes, methods,
and fields can be accessed from
everywhere. Fill in the blank.
a) private
b) public
c) protected
d) default
Page: 30

Ans: b) public
Explanation: public classes, methods,
and fields can be accessed from
everywhere. The only constraint is that a
file with Java source code can only
contain one public class whose name
must also match with the filename. You
use public classes, methods, or fields only
if you explicitly want to offer access to
these entities and if this access cannot do
any harm.
If you do not set access to specific level,
then such a class, method, or field will be
accessible from inside the same package
to which the class, method, or field
belongs, but not from outside this
package.
Page: 31

MCQ No: 16
___________ access level when it
is appropriate for a class's
subclasses to have access to the
method or field, but not for
unrelated classes. Fill in the blank.
a) default
b) protected
c) public
d) private
Page: 32

Ans: b) protected
Explanation:
protected methods and fields can
only be accessed within the same
class to which the methods and
fields belong, within its subclasses,
and within classes of the same
package, but not from anywhere
else. You use the protected access
level when it is appropriate for a
class's subclasses to have access to
the method or field, but not for
unrelated classes.
Page: 33

MCQ No: 17
________ methods and fields can
only be accessed within the same
class to which the methods and
fields belong. Fill in the blank.
a) private
b) public
c) protected
d) default
Page: 34

Ans: a) private
Explanation:
private methods and fields can only
be accessed within the same class to
which the methods and fields belong.
private methods and fields are not
visible within subclasses and are not
inherited by subclasses. So, the
private access specifier is opposite to
the public access specifier. It is mostly
used for encapsulation: data are
hidden within the class and accessor
methods are provided.
Page: 35

MCQ No: 18
The conditional expression of an if-
statement in java must be a
_______________ . Fill in the
blank.
a) Arithmetic expression
b) Boolean expression
c) Non- Zero value
d) Zero value
Page: 36

Ans: b) Boolean expression
Explanation:
The if statement executes a block of
code only if the specified expression
is true. If the value is false, then the
if block is skipped and execution
continues with the rest of the
program. Note that the conditional
expression must be a Boolean
expression, which must give TRUE
or FALSE value. Any other
value(Zero or Non-Zero value) will
give compilation error.
Page: 37

MCQ No: 19
The switch statement code block in
Java includes a __________ label
to use in cases where there are no
matches are found. Fill in the
blank.
a) outer
b) default
c) inner
d) continue
Page: 38

Ans: b) default
Explanation:
The switch case statement, also
called a case statement is a multi-way
branch with several choices. A switch
is easier to implement than a series of
if/else statements. The default level is
used to execute statements when no
matches are found.
Page: 39

MCQ No: 20
When executing a switch
statement, the program falls
through to the next case.
Therefore, if you want to exit in the
middle of the switch statement
code block, you must insert a
_______________ . Fill in the
blank.
a) case statement
b) default statement
c) break statement
d) continue statement
Page: 40

Ans: c) break statement
Explanation:
When executing a switch statement,
the program falls through to the next
case. Therefore, if you want to exit in
the middle of the switch statement
code block, you must insert a break
statement, which causes the
program to continue executing after
the current code block.
Page: 41

Multiple Choice Questions on JAVA (object oriented programming) bank 3 -- class,objects,conditional statements

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