Java Fundamentals MCQs (Multiple Choice Questions)

Q1 What is the correct syntax for declaring a new array in Java?

A int[] myArray = {1, 2, 3, 4};B int() myArray = {1, 2, 3, 4};C array myArray = {1, 2, 3, 4};D int myArray = [1, 2, 3, 4];

Q2 Which of the following is not a primitive data type in Java?

A intB longC floatD String

Q3 What is the output of the following Java code?

int x = 5;
int y = 10;
int z = x + y;
System.out.println(z);

A 5B 10C 15D 25

Q4 What is the purpose of the “final” keyword in Java?

A It indicates that a variable is a constant and cannot be changed.B It indicates that a method cannot be overridden by a subclass.C It indicates that a class cannot be subclassed.D All of the above.E None of the above.

Q5 Which of the following is not a valid looping construct in Java?

A forB whileC do-whileD repeat

Q6 What is the output of the following Java code?

int x = 10;
int y = 20;
if (x > y) {
  System.out.println("x is greater than y");
} else if (x < y) {
  System.out.println("x is less than y");
} else {
  System.out.println("x is equal to y");
}

A x is greater than yB x is less than yC x is equal to yD None of the above

Q7 Which of the following data types is used to store a single character in Java?

A intB booleanC charD String

Q8 What does JVM stand for?

A Java Virtual MachineB Java Volatile MemoryC Just Virtual MachineD None of the above

Q9 Which keyword is used to create a class in Java?

A classB ClassC newD Object

Q10 Which method is called when a Java program starts?

A start()B run()C init()D main()

Q11 What is the size of a char in Java?

A 8 bitsB 16 bitsC 32 bitsD 64 bits

Q12 Which of the following is a valid declaration of a String?

A String str = "Hello";B string str = "Hello";C Str str = "Hello";D Txt str = "Hello";

Q13 Which operator is used to compare two values?

A =B ==C !=D ===

Q14 What is the result of the expression 9 % 2?

A 0.5B 4.5C 1D 2

Q15 Which of the following is a loop construct in Java?

A do-whileB repeat-untillC forD Both A and C

Q16 What is encapsulation in Java?

A A process of wrapping code and data together into a single unit.B Linking of a program with its dependencies.C Hiding internal state and requiring all interaction to be performed through an object's methods.D Both A and C

Q17 Which keyword is used to inherit a class in Java?

A extendsB implementsC inheritsD super

Q18 How many constructors can a class have in Java?

A Only oneB Atleast oneC As many as neededD None

Q19 Which of these access specifiers can be used for an interface?

A publicB protectedC privateD None of the above

Q20 What is the default value of a local variable in Java?

A nullB 0C Depends on the typeD Not assigned

Q21 What is the output of?

System.out.println(10+20+"Hello"+10+20);

A 30Hello1020B 30Hello30C 1020Hello1020D 1020Hello30

Q22 Which keyword is used to access the superclass in Java?

A thisB superC extendsD base

Q23 What does the expression evaluate to?

boolean isTrue = !false;

A falseB 0C trueD 1

Q24 What is polymorphism in Java?

A The ability of a variable, function or object to take on multiple forms.B The concept of wrapping data and methods that operate on the data into a single unit.C The process of moving the common code up into the superclass.D The ability of Java to run on various operating systems.

Q25 What will be the output of the following Java code snippet?

int a = 10;
int b = ++a + a++ + --a + a--;
System.out.println(b);

A 42B 43C 44D 45

Q26 Which collection class allows you to grow or shrink its size and provides indexed access to its elements, but is not synchronized?

A HashSetB HashMapC ArrayListD Hashtable

Q27 What will be the result of compiling and running the following Java code snippet?

public class Test {
    public static void main(String[] args) {
        int x = 10;
        int y = new Test().change(x);
        System.out.print(x + y);
    }
    int change(int x) {
        x = 12;
        return x;
    }
}

A 20B 22C 24D 10

Q28 Which of the following is true about a final class in Java?

A It can be extended.B It can extend other classes.C It cannot be extended.D It cannot extend other classes.

Q29 Which interface does java.util.Hashtable implement?

A MapB JMapC ListD HashMap

Q30 What is the default value of a static variable of type int?

A 0B nullC Not assignedD Compiles with an error

Q31 Which method must be implemented by all threads in Java?

A start()B run()C stop()D execute()

Q32 Which of these is used to make an object of a class serializable in Java?

A Serializable interfaceB Serialize interfaceC Serialized interfaceD ObjectOutput interface

Q33 Which keyword is used to prevent method overriding in Java?

A finalB staticC abstractD private

Q34 How can you access the first element of an array named arr?

A arr[1]B arr[0]C arr.first()D arr.get(0)

Q35 Which of these is a valid Java identifier?

A 123abcB java.utilC $helloD -variable

Q36 Which class in Java is used for parsing strings to numbers?

A StringB MathC IntegerD NumberFormat

Q37 What is the size of an int in Java?

A 8 bitsB 16 bitsC 32 bitsD 64 bits

Q38 Which exception is thrown when trying to access a class for which a definition is not found?

A ClassNotFoundExceptionB NoClassDefFoundErrorC ClassCastExceptionD ClassNotFoundException and NoClassDefFoundError

Q39 In Java, which operator is used for instance comparison?

A ==B ===C instanceofD equals()

Q40 What does the transient keyword in Java do?

A Marks a variable to not be serialized.B Temporarily creates variables.C Makes an instance variable transient.D None of the above.

Q41 Which of the following is true about the switch statement in Java?

A It can work with byte, short, int, long, enum types, String objects, and a few special classes like Character and Integer.B It can work with byte, short, int, enum types, and String objects.C It only works with integer types.D It cannot work with String objects.

Q42 What will this code print?

System.out.println('100');

A 100B 100C A special character represented by octal 100.D Error

Q43 Which of the following is not a wrapper class in Java?

A CharacterB StringC IntegerD Boolean

Q44 How do you ensure that a resource is automatically closed at the end of the statement block?

A Use the finally block.B Use a while loop.C Use the try-with-resources statement.D Manually close it inside the catch block.

Q45 What is the purpose of the super keyword in Java?

A To call the superclass version of a method.B To access a method in a superclass.C To call the constructor of a superclass.D All of the above.

Q46 Which of these collections is ordered?

A HashSetB TreeSetC HashMapD LinkedHashMap

Q47 What will be the result of compiling and running the following code?

int a = null;
System.out.println(a);

A nullB 0C Compilation errorD An exception at runtime

Q48 Which of these access specifiers allows visibility only within the same package and subclasses?

A privateB No modifier (default)C protectedD public

Q49 In Java, how do you declare a variable that cannot be modified after it is initialized?

A dynamicB mutableC finalD constant

Q50 What is autoboxing in Java?

A Automatically converting a primitive type into its corresponding wrapper class objectB Automatically packing multiple values into a single objectC Automatically increasing the size of an arrayD Automatically updating the value of a wrapper object

Q51 Which of the following is true about the enum type in Java?

A enum can only contain constants.B enum can be declared inside a class or outside.C enum constants are public, static, and final by default.D All of the above.

Q52 What does the static keyword in Java indicate?

A That a particular field or method belongs to a class, rather than instances of itB That a method cannot be overriddenC That a variable or method is thread-safeD That an inner class can be accessed without an instance of the outer class

Q53 Which of the following is not a Java control statement?

A if-elseB forC includeD switch

Q54 In Java, what is method overloading?

A Defining multiple methods with the same name but different method signatures within the same classB Overriding a superclass method in a subclassC Increasing the visibility of a method in a subclassD Changing the return type of a method in a subclass

Q55 In Java, which of the following is the correct way to declare a variable of type float?

A float f = 1.0;B float f = 1.0f;C float f = 1F;D Both B and C

Q56 Which of the following is true about the static keyword in Java?

A It can be applied to blocks.B It can be applied to methods.C It can be applied to variables.D All of the above.

Q57 Which of the following loop constructs will run at least once?

A forB whileC do-whileD foreach

Q58 What is the result of 10 >> 2 in Java?

A 2B 2.5C 5D 25

Q59 What is the correct syntax for defining an interface in Java?

A class MyInterface {}B interface MyInterface;C interface MyInterface {}D Interface MyInterface {}

Q60 Which method is used to compare two strings for equality in Java?

A compare()B equals()C compareTo()D ==

Q61 In Java, which keyword is used to reference the current object?

A selfB thisC meD itself

Q62 Which of these is not a visibility modifier in Java?

A transientB protectedC privateD public

Q63 What does the finally block in a try-catch structure do?

A It is executed if an exception occurs.B It is executed after the try block but before the catch block.C It is executed whether an exception is thrown or not.D It is used to finally declare variables.

Q64 What is the base class of all classes in Java?

A BaseB MainC ObjectD Java.lang

Q65 Which of these is a correct way to allocate memory to an array in Java?

A int arr[] = new int[5];B int arr[]; arr = new int[5];C int[] arr = new int[5];D All of the above

Q66 What does the abstract keyword mean in Java?

A The method cannot be used.B The method must be implemented by subclasses.C The method does not have a body.D Both B and C

Q67 Which of the following is true about package in Java?

A It is used to categorize classes and interfaces.B It helps to avoid name clashes.C It can be imported using the import keyword.D All of the above

Q68 What is the output of the following snippet?

String s1 = "Java";
String s2 = new String("Java");
System.out.println(s1 == s2);

A trueB falseC Compilation ErrorD Runtime Error

Q69 In Java, constructor overloading:

A Is not allowed.B Means creating multiple constructors with different parameters.C Means creating multiple constructors with same parameters.D None of the above.

Q70 Which of the following is not an OOP principle?

A EncapsulationB InheritanceC CompilationD Polymorphism

Q71 The continue statement in Java:

A Terminates the loop immediately.B Skips the current iteration and proceeds to the next iteration.C Is used to exit from a switch statement.D Is used in a try-catch block to skip to the finally block.

Q72 What will be the output of the following code?

for(int i=0; i<5; i++){
    if(i==3)
        break;
    System.out.print(i + " ");
}

A 0 1 2 3B 0 1 2C 0 1 2 3 4D 1 2 3 4

Q73 An instance of which of the following can be changed after it is created?

A StringB StringBuilderC StringBufferD Both B and C

Q74 What is the scope of package-level access modifier in Java?

A Within the same class only.B Within the same package only.C Within the same package and all subclasses.D Everywhere.

Q75 Which of these is not a Java feature?

A DynamicB Use of pointersC Object-orientedD Platform-independent

Q76 The finalize() method in Java is called:

A Just before garbage collection.B Immediately after an object goes out of scope.C Before an object is created.D After a method call on an object completes.

Q77 Which of these is a valid declaration of a byte array in Java?

A byte[] arr = new byte[5];B byte arr[] = new byte[5];C byte arr[5];D Both A and B

Q78 Which keyword is used for synchronizing a block of code in Java?

A synchronizedB volatileC staticD final

Q79 Which exception is thrown when accessing an out-of-bound index of an array in Java?

A ArrayIndexOutOfBoundsExceptionB IndexOutOfBoundsExceptionC OutOfBoundsExceptionD Exception