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This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.

1.

final class Complex {private final double re;private final double im;public Complex(double re, double im) {this.re = re;this.im = im;}public String toString() {return "(" + re + " + " + im + "i)";}}class Main {public static void main(String args[]){Complex c = new Complex(10, 15);System.out.println("Complex number is " + c);}}(A)Complex number is (10.0 + 15.0i)(B) Compiler Error(C)Complex number is SOME_GARBAGE(D)Complex number is Complex8e2fb5Here 8e2fb5 is hash code of c

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2.

Predict the output of following program. Note that foo() is public in base and private in derived.class Base {public void foo() { System.out.println("Base"); }}class Derived extends Base {private void foo() { System.out.println("Derived"); }}public class Main {public static void main(String args[]) {Base b = new Derived();b.foo();}}(A) Base(B) Derived(C) Compiler Error(D) Runtime Error

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3.

Which of the following is true about inheritance in Java.1) In Java all classes inherit from the Object class directly or indirectly. The Object class is root of all classes.2) Multiple inheritance is not allowed in Java.3) Unlike C++, there is nothing like type of inheritance in Java where we can specify whether the inheritance is protected, public or private.(A) 1, 2 and 3(B) 1 and 2(C) 2 and 3(D) 1 and 3

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4.

class Base {final public void show() {System.out.println("Base::show() called");}}class Derived extends Base {public void show() {System.out.println("Derived::show() called");}}class Main {public static void main(String[] args) {Base b = new Derived();;b.show();}}(A) Base::show() called(B) Derived::show() called(C) Compiler Error(D) Runtime Error

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5.

Output of following Java program?class Base {public void Print() {System.out.println("Base");}}class Derived extends Base {public void Print() {System.out.println("Derived");}}class Main{public static void DoPrint( Base o ) {o.Print();}public static void main(String[] args) {Base x = new Base();Base y = new Derived();Derived z = new Derived();DoPrint(x);DoPrint(y);DoPrint(z);}}(A)BaseDerivedDerived(B)BaseBaseDerived(C)BaseDerivedBase(D) Compiler Error

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6.

class Base {public static void show() {System.out.println("Base::show() called");}}class Derived extends Base {public static void show() {System.out.println("Derived::show() called");}}class Main {public static void main(String[] args) {Base b = new Derived();b.show();}}(A) Base::show() called(B) Derived::show() called(C) Compiler Error

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7.

Which of the following is true about inheritance in Java?1) Private methods are final.2) Protected members are accessible within a package and inherited classes outside the package.3) Protected methods are final.4) We cannot override private methods. (A) 1, 2 and 4(B) Only 1 and 2(C) 1, 2 and 3(D) 2, 3 and 4

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8.

What would be the result if a class extends two interfaces and both have a method with same name and signature? Lets assume that the class is not implementing that method.(a) Runtime error(b) Compile time error(c) Code runs successfully(d) First called method is executed successfullyThis question was posed to me in an online interview.Question is taken from Inheritance in chapter Inheritance of Java

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The correct choice is (b) COMPILE TIME error

To explain I WOULD SAY: In case of such CONFLICT, compiler will not be able to link a method call due to ambiguity. It will throw compile time error.
Discussion
9.

Does Java support multiple level inheritance?(a) True(b) FalseI had been asked this question during an online exam.This is a very interesting question from Inheritance topic in chapter Inheritance of Java

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Correct option is (a) True

To explain I would say: JAVA SUPPORTS MULTIPLE LEVEL inheritance through implementing multiple INTERFACES.
Discussion
10.

Which of the following is used for implementing inheritance through class?(a) inherited(b) using(c) extends(d) implementsI have been asked this question during an internship interview.I would like to ask this question from Inheritance topic in portion Inheritance of Java

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The CORRECT OPTION is (c) extends

For explanation: CLASS can be extended USING extends keyword. One class can extend only one class. A FINAL class cannot be extended.
Discussion
11.

Which of the following is used for implementing inheritance through an interface?(a) inherited(b) using(c) extends(d) implementsI got this question in an internship interview.This question is from Inheritance in division Inheritance of Java

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Correct answer is (d) implements

To elaborate: INTERFACE is implemented USING implements KEYWORD. A concrete CLASS must implement all the METHODS of an interface, else it must be declared abstract.
Discussion
12.

If super class and subclass have same variable name, which keyword should be used to use super class?(a) super(b) this(c) upper(d) classnameThe question was asked at a job interview.This interesting question is from Inheritance in portion Inheritance of Java

Answer» CORRECT answer is (a) super

For explanation I WOULD say: Super keyword is used to access HIDDEN super class VARIABLE in subclass.
Discussion
13.

Static members are not inherited to subclass.(a) True(b) FalseThis question was addressed to me in quiz.My question is from Inheritance in division Inheritance of Java

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Right CHOICE is (B) False

The best explanation: STATIC members are also INHERITED to subclasses.
Discussion
14.

In order to restrict a variable of a class from inheriting to subclass, how variable should be declared?(a) Protected(b) Private(c) Public(d) StaticThe question was posed to me by my college director while I was bunking the class.This intriguing question originated from Inheritance in chapter Inheritance of Java

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The correct answer is (b) Private

Explanation: By declaring VARIABLE private, the variable will not be AVAILABLE in inherited to SUBCLASS.
Discussion
15.

All classes in Java are inherited from which class?(a) java.lang.class(b) java.class.inherited(c) java.class.object(d) java.lang.ObjectI got this question in semester exam.My question is taken from Inheritance topic in portion Inheritance of Java

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Right option is (d) java.lang.OBJECT

To EXPLAIN I would SAY: All classes in java are INHERITED from Object class. INTERFACES are not inherited from Object Class.
Discussion
16.

Using which of the following, multiple inheritance in Java can be implemented?(a) Interfaces(b) Multithreading(c) Protected methods(d) Private methodsI had been asked this question in semester exam.Question is from Inheritance in portion Inheritance of Java

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Right option is (a) INTERFACES

Easy EXPLANATION: MULTIPLE inheritance in java is IMPLEMENTED using interfaces. Multiple interfaces can be implemented by a class.
Discussion
17.

What is not type of inheritance?(a) Single inheritance(b) Double inheritance(c) Hierarchical inheritance(d) Multiple inheritanceI had been asked this question during an interview.This interesting question is from Inheritance topic in division Inheritance of Java

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Right option is (b) DOUBLE inheritance

The best explanation: Inheritance is way of ACQUIRING ATTRIBUTES and methods of parent class. Java SUPPORTS HIERARCHICAL inheritance directly.
Discussion
18.

A class member declared protected becomes a member of subclass of which type?(a) public member(b) private member(c) protected member(d) static memberThe question was posed to me in a national level competition.Origin of the question is Inheritance topic in chapter Inheritance of Java

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The CORRECT OPTION is (b) private MEMBER

To ELABORATE: A class member declared protected becomes a private member of subclass.
Discussion
19.

A class member declared protected becomes a member of subclass of which type?(a) public member(b) private member(c) protected member(d) static memberThis question was addressed to me during a job interview.This key question is from Inheritance topic in chapter Inheritance of Java

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20.

If a class inheriting an abstract class does not define all of its function then it will be known as?(a) Abstract(b) A simple class(c) Static class(d) None of the mentionedI got this question during an interview for a job.Asked question is from Inheritance topic in section Inheritance of Java

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Correct choice is (a) Abstract

The best explanation: Any subclass of an abstract class must either IMPLEMENT all of the abstract method in the SUPERCLASS or be itself DECLARED abstract.
Discussion
21.

Which of this keyword must be used to inherit a class?(a) super(b) this(c) extent(d) extendsThe question was posed to me during an online interview.I want to ask this question from Inheritance in chapter Inheritance of Java

Answer» CORRECT ANSWER is (d) extends

For EXPLANATION: NONE.
Discussion
22.

Which of these is not a correct statement?(a) Every class containing abstract method must be declared abstract(b) Abstract class defines only the structure of the class not its implementation(c) Abstract class can be initiated by new operator(d) Abstract class can be inheritedI had been asked this question during an online interview.The query is from Inheritance topic in section Inheritance of Java

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The CORRECT choice is (c) Abstract class can be initiated by new OPERATOR

To EXPLAIN I WOULD say: Abstract class cannot be directly initiated with new operator, Since abstract class does not contain any definition of implementation it is not possible to CREATE an abstract object.
Discussion
23.

Which of these keywords are used to define an abstract class?(a) abst(b) abstract(c) Abstract(d) abstract classThe question was asked by my college professor while I was bunking the class.This intriguing question originated from Inheritance in division Inheritance of Java

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The CORRECT answer is (B) abstract

The best I can EXPLAIN: NONE.
Discussion
24.

Which of these is not abstract?(a) Thread(b) AbstractList(c) List(d) None of the MentionedI had been asked this question during a job interview.This key question is from Inheritance topic in division Inheritance of Java

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Correct CHOICE is (a) Thread

To explain I WOULD say: Thread is not an abstract class.
Discussion
25.

Which of these keywords cannot be used for a class which has been declared final?(a) abstract(b) extends(c) abstract and extends(d) none of the mentionedThe question was posed to me in an online interview.I'm obligated to ask this question of The Object Class topic in section Inheritance of Java

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The correct answer is (a) abstract

For EXPLANATION: A abstract class is incomplete by itself and relies upon its SUBCLASSES to PROVIDE a complete implementation. If we declare a class FINAL then no class can inherit that class, an abstract class needs its subclasses HENCE both final and abstract cannot be used for a same class.
Discussion
26.

Which of these keywords can be used to prevent inheritance of a class?(a) super(b) constant(c) class(d) finalThis question was posed to me during an internship interview.The origin of the question is The Object Class topic in portion Inheritance of Java

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The correct CHOICE is (d) final

For EXPLANATION I would say: Declaring a CLASS final implicitly declared all of its methods final, and MAKES the class INHERITABLE.
Discussion
27.

Which of these method of Object class is used to obtain class of an object at run time?(a) get()(b) void getclass()(c) Class getclass()(d) None of the mentionedThe question was posed to me in my homework.Question is taken from The Object Class topic in chapter Inheritance of Java

Answer» CORRECT ANSWER is (C) Class getclass()

Best EXPLANATION: None.
Discussion
28.

Which of these method of Object class can clone an object?(a) Objectcopy()(b) copy()(c) Object clone()(d) clone()I got this question in semester exam.The question is from The Object Class in division Inheritance of Java

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The correct choice is (C) Object CLONE()

The EXPLANATION: NONE.
Discussion
29.

Which of these class is superclass of every class in Java?(a) String class(b) Object class(c) Abstract class(d) ArrayList classI had been asked this question in an interview for internship.I'm obligated to ask this question of The Object Class in division Inheritance of Java

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Correct OPTION is (b) Object CLASS

For explanation I WOULD say: Object class is superclass of EVERY class in Java.
Discussion
30.

Which of these keywords can be used to prevent Method overriding?(a) static(b) constant(c) protected(d) finalThis question was addressed to me in unit test.I'm obligated to ask this question of Method overriding in chapter Inheritance of Java

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The correct OPTION is (d) final

Easy explanation: To disallow a method from being OVERRIDDEN, specify final as a modifier at the start of its declaration. METHODS DECLARED as final cannot be overridden.
Discussion
31.

Which of these is correct way of calling a constructor having no parameters, of superclass A by subclass B?(a) super(void);(b) superclass.();(c) super.A();(d) super();I had been asked this question during an interview for a job.My question is from Method overriding topic in chapter Inheritance of Java

Answer» RIGHT answer is (d) SUPER();

BEST explanation: NONE.
Discussion
32.

What is the process of defining a method in a subclass having same name & type signature as a method in its superclass?(a) Method overloading(b) Method overriding(c) Method hiding(d) None of the mentionedThis question was posed to me in unit test.My enquiry is from Method overriding topic in portion Inheritance of Java

Answer» CORRECT ANSWER is (B) METHOD overriding

Explanation: NONE.
Discussion
33.

Which of this keyword can be used in a subclass to call the constructor of superclass?(a) super(b) this(c) extent(d) extendsThe question was asked in an online quiz.The doubt is from Method overriding in chapter Inheritance of Java

Answer» RIGHT ANSWER is (a) super

Easy EXPLANATION: NONE.
Discussion