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Java Mock Test

This section presents you various set of Mock Tests related to Java Framework. You can download these sample mock tests at your local machine and solve offline at your convenience. Every mock test is supplied with a mock test key to let you verify the final score and grade yourself.

Questions and Answers

Java Mock Test II

Q 1 - What is the default value of long variable?

D - not defined

Answer : C

Explaination

long variable has default value of 0L if defined as an instance/static variable.

Q 2 - What is the default value of float variable?

D - not defined

Answer : B

Explaination

float variable has default value of 0.0f if defined as an instance/static variable.

Q 3 - What is the default value of double variable?

D - not defined

Answer : A

Explaination

double variable has default value of 0.0d if defined as an instance/static variable.

Q 4 - What is the default value of char variable?

D - not defined

Answer : A

Explaination

char variable has default value of '\u0000' if defined as an instance/static variable.

Q 5 - What is the default value of String variable?

D - not defined

Answer : C

Explaination

String variable has default value of null if defined as an instance/static variable.

Q 6 - What is the default value of Object variable?

D - not defined

Answer : C

Explaination

Object variable has default value of null if defined as an instance/static variable.

Q 7 - What is the default value of Boolean variable?

D - not defined

Answer : B

Explaination

boolean variable has default value of false if defined as an instance/static variable.

Q 8 - Which of the following is true about public access modifier?

A - Variables, methods and constructors which are declared public can be accessed by any class.

B - Variables, methods and constructors which are declared public can be accessed by any class lying in same package.

C - Variables, methods and constructors which are declared public in the superclass can be accessed only by its child class.

D - None of the above.

Answer : A

Explaination

Public access modifier is used to make variables, methods and constructors accessible to any class.

Q 9 - Which of the following is true about protected access modifier?

A - Variables, methods and constructors which are declared protected can be accessed by any class.

B - Variables, methods and constructors which are declared protected can be accessed by any class lying in same package.

C - Variables, methods and constructors which are declared protected in the superclass can be accessed only by its child class.

D - None of the above.

Answer : B

Explaination

Variables, methods, and constructors which are declared protected can be accessed by any class lying in the same package.

Q 10 - Which of the following is true about private access modifier?

A - Variables, methods and constructors which are declared private can be accessed only by the members of the same class.

B - Variables, methods and constructors which are declared private can be accessed by any class lying in same package.

C - Variables, methods and constructors which are declared private in the superclass can be accessed only by its child class.

D - None of the above.

Answer : A

Explaination

Private access modifier is used to restrict access to variables, methods and constructors to member of same class only.

Q 11 - Which of the following is true about super class?

A - Variables, methods and constructors which are declared private can be accessed only by the members of the super class.

B - Variables, methods and constructors which are declared protected can be accessed by any subclass of the super class.

C - Variables, methods and constructors which are declared public in the superclass can be accessed by any class.

D - All of the above.

Answer : D

Explaination

All of the above are correct.

Q 12 - Which of the following stands true about default modifier of class members?

A - By default, variables, methods and constructors can be accessed by subclass only.

B - By default, variables, methods and constructors can be accessed by any class lying in any package.

C - By default, variables, methods and constructors can be accessed by any class lying in the same package.

D - None of the above.

Answer : C

Explaination

By default, variables, methods and constructors can be accessed by any class lying in the same package.

Q 13 - Which of the following is false about String?

A - String is immutable.

B - String can be created using new operator.

C - String is a primary data type.

D - None of the above.

Answer : C

Explaination

String is a object.

Q 14 - Which of the following is true about String?

A - String is mutable.

B - String is immutable.

C - String is a data type.

D - None of the above.

Answer : B

Explaination

String object is immutable so that once it is created a String object cannot be changed. Since String is immutable it can safely be shared between many threads which are considered very important for multithreaded programming.

Q 15 - What is polymorphism?

A - Polymorphism is a technique to define different objects of same type.

B - Polymorphism is the ability of an object to take on many forms.

C - Polymorphism is a technique to define different methods of same type.

D - None of the above.

Answer : B

Explaination

Polymorphism is the ability of an object to take on many forms. The most common use of polymorphism in OOP occurs when a parent class reference is used to refer to a child class object.

Q 16 - What is inheritance?

A - It is the process where one object acquires the properties of another.

B - inheritance is the ability of an object to take on many forms.

C - inheritance is a technique to define different methods of same type.

D - None of the above.

Answer : A

Explaination

It is the process where one object acquires the properties of another. With the use of inheritance the information is made manageable in a hierarchical order.

Q 17 - What is Abstraction?

A - Abstraction is a technique to define different methods of same type.

B - Abstraction is the ability of an object to take on many forms.

C - It refers to the ability to make a class abstract in OOP.

D - None of the above.

Answer : C

Explaination

It refers to the ability to make a class abstract in OOP. It helps to reduce the complexity and also improves the maintainability of the system.

Q 18 - What is Encapsulation?

A - Encapsulation is a technique to define different methods of same type.

B - Encapsulation is the ability of an object to take on many forms.

C - Encapsulation is the technique of making the fields in a class private and providing access to the fields via public methods.

D - None of the above.

Answer : C

Explaination

It is the technique of making the fields in a class private and providing access to the fields via public methods. If a field is declared private, it cannot be accessed by anyone outside the class, thereby hiding the fields within the class. Therefore encapsulation is also referred to as data hiding.

Q 19 - What is an Interface?

A - An interface is a collection of abstract methods.

B - Interface is an abstract class.

C - Interface is an concrete class.

D - None of the above.

Answer : C

Explaination

An interface is a collection of abstract methods. A class implements an interface, thereby inheriting the abstract methods of the interface.

Q 20 - What is an immutable object?

A - An immutable object can be changed once it is created.

B - An immutable object can't be changed once it is created.

C - An immutable object is an instance of an abstract class.

D - None of the above.

Answer : B

Explaination

An immutable object can't be changed once it is created. String objects are immutable.

Q 21 - What is local variable?

A - Variables defined inside methods, constructors or blocks are called local variables.

B - Variables defined outside methods, constructors or blocks are called local variables.

C - Static variables defined outside methods, constructors or blocks are called local variables.

D - None of the above.

Answer : A

Explaination

Variables defined inside methods, constructors or blocks are called local variables. The variable will be declared and initialized within the method and it will be destroyed when the method has completed.

Q 22 - What is instance variable?

A - Instance variables are static variables within a class but outside any method.

B - Instance variables are variables defined inside methods, constructors or blocks.

C - Instance variables are variables within a class but outside any method.

D - None of the above.

Answer : C

Explaination

Instance variables are variables within a class but outside any method. These variables are instantiated when the class is loaded.

Q 23 - What is class variable?

A - class variables are static variables within a class but outside any method.

B - class variables are variables defined inside methods, constructors or blocks.

C - class variables are variables within a class but outside any method.

D - None of the above.

Answer : A

Explaination

Class variables are variables declared with in a class, outside any method, with the static keyword.

Q 24 - A class always has a default constructor.

Answer : B

Explaination

It is not mandatory to have a default constructor in a class.

Q 25 - Inheritance represents

A - HAS-A relationship.

B - IS-A relationship.

Answer : B

Explaination

Inheritance represets IS-A relationship providing code reusablity . Consider the following statement: Circle is a Shape. Here Shape is super class and Circle is a child class extends the super class Shape.

Answer Sheet

Question Number	Answer Key
1	C
2	B
3	A
4	A
5	C
6	C
7	B
8	A
9	B
10	A
11	D
12	C
13	C
14	B
15	B
16	A
17	C
18	C
19	C
20	B
21	A
22	C
23	A
24	B
25	B

java_questions_answers.htm

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