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Go through Java Theory Notes on Constructor Overloading before reading these objective questions.
1) A Java constructor is like a method without ___.
A) statements
B) return type
C) argument list
D) None
B
2) The name of a constructor and the name of a class are ___.
A) Same
B) Different
C) -
D) -
A
3) The placement of a constructor inside a class should be ___.
A) Always at the beginning of class
B) Always at the end of class
C) Anywhere in the class
D) None
C
4) The purpose of a Java constructor is ___.
A) Initialization of variables with passed data
B) Writing custom code
C) Accepting other objects as inputs
D) All the above
D
5) Memory is allocated to an object once the execution of ___ is over in Java language.
A) main method
B) constructor
C) destructor
D) None
B
6) What is the output of the below Java program?
public class TestingConstructor
{
void TestingConstructor()
{
System.out.println("Amsterdam");
}
TestingConstructor()
{
System.out.println("Antarctica");
}
public static void main(String[] args)
{
TestingConstructor tc = new TestingConstructor();
}
}
A) Antarctica
B) Amsterdam
C) No output
D) Compiler error
A
Explanation:
Here the constructor is TestingConstructor() without return type.
7) In Java, a constructor with no parameters or no arguments is called ___ constructor.
A) Default constructor
B) User-defined constructor
C) -
D) -
A
8) In Java, a constructor with one or more arguments or parameters is called a ___ constructor.
A) Default constructor
B) User-defined constructor or Non-default constructor
C) -
D) -
B
9) The compiler adds a default no-argument constructor to a class if it ___.
A) does not define a constructor at all.
B) defines at least one constructor with arguments
C) -
D) -
A
10) Overloading of constructors in Java means adding more than ___ constructors with the different argument list.
A) 1
B) 2
C) 3
D) 8
A
11) What is the output of the below Java program with constructors?
public class Constructor2
{
int count=10;
Constructor2(int count)
{
System.out.println("Count=" + count);
}
public static void main(String[] args)
{
Constructor2 con = new Constructor2();
}
}
A) Count=0
B) Count=10
C) Compiler error
D) None of the above
C
Explanation:
If you write a constructor with arguments, the default constructor is not added by the compiler. You should add it explicitly.
12) A constructor can call another overloaded constructor using the ___ keyword in Java.
A) super
B) local
C) con
D) this
D
13) What is the output of the below Java program with overloaded constructors?
public class Constructor3
{
int birds=10;
Constructor3()
{
this(20);
}
Constructor3(int birds)
{
System.out.println("Birds=" + birds);
}
public static void main(String[] args)
{
Constructor3 con = new Constructor3();
}
}
A) Birds=0
B) Birds=10
C) Birds=20
D) Compiler error
C
Explanation:
You can pass parameters to another constructor.
14) In Java, you can pass __ variables from one constructor to another overloaded constructor.
A) local variables
B) static variables
C) non-static variables
D) local and static variables
D
15) Choose the correct way of calling the second constructor from the first constructor in the below code options.
A)
Constructor5()
{
int a=30;
this('A');
}
Constructor5(char c)
{
//
}
B)
Constructor5()
{
int a=30;
this('A');
System.out.println("Success");
}
Constructor5(char c)
{
//
}
C)
Constructor5()
{
this('A');
System.out.println("Success");
}
Constructor5(char c)
{
//
}
D) All the above
C
Explanation:
Only the first statement should call another constructor.
16) What is the output of the below Java program with many constructors?
public class Constructor7
{
Constructor7(int a)
{
System.out.println("Book=" + a);
}
Constructor7(float a)
{
System.out.println("Pen="+ a );
}
public static void main(String[] args)
{
Constructor7 con = new Constructor7(50.5f);
}
}
A) Book=50
B) Pen=50.5
C) Compiler error
D) None of the above
B
Explanation:
Constructor overloading allows constructors with different arguments at the same time.
17) What is the output of the below Java program with many constructors?
public class Constructor8
{
Constructor8(boolean a)
{
System.out.println("MODEM="+ a );
}
Constructor8(float a)
{
System.out.println("ROUTER=" + a);
}
public static void main(String[] args)
{
Constructor8 con1 = new Constructor8(50);
Constructor8 con2 = new Constructor8(false);
}
}
A)
ROUTER=50.0 MODEM=false
B)
ROUTER=50 MODEM=false
C) Compiler error
D) None
A
Explanation:
Java knows when to typecast a variable to a higher type like a float from int. So the number 50 is passed to a constructor accepting a float argument as there is no constructor accepting int argument above.
18) What is the output of the below Java program with overloaded constructors?
public class Jiraffe
{
Jiraffe(int sugarcanes)
{
System.out.println("Eats "+ sugarcanes + " Sugarcanes");
}
Jiraffe(int age, int...sugarcanes)
{
System.out.println("Eats "+ sugarcanes[0] + " Sugarcanes");
}
public static void main(String[] args)
{
Jiraffe jiff2 = new Jiraffe(40);
Jiraffe jiff = new Jiraffe(5,10);
}
}
A)
2.Eats 40 Sugarcanes 2.Eats 10 Sugarcanes
B)
1.Eats 40 Sugarcanes 2.Eats 10 Sugarcanes
C) Compiler error
D) None
B
Explanation:
Java supports using the varargs in constructors.
19) Choosing a suitable overloaded constructor happens at ___ time in Java.
A) Compile-time
B) Run time
C) -
D) -
B
20) Java constructor overloading follows ___ principle in Object-Oriented programming.
A) Inheritance
B) Encapsulation
C) Polymorphism
D) None
C
Explanation:
Overloading of constructors requires you to specify the same name to all constructors. So, it satisfies the polymorphism principle of Oops.
21) Java allows calling or invoking a method from a constructor. State TRUE or FALSE.
A) TRUE
B) FALSE
C) -
D) -
A
22) What is the output of the below Java program?
public class Constructor9
{
Constructor9()
{
show();
}
void show()
{
System.out.println("JAM JAM");
}
public static void main(String[] args)
{
Constructor9 con = new Constructor9();
}
}
A) JAM JAM
B) No output
C) Compiler error
D) None
A
Explanation:
Invoking a method from within a constructor is allowed.
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