Java Online Quiz

January 29, 2021

Below are the instructions for this quiz:

• Time Limit for this Quiz is 30 minutes
• This quiz has 20 questions
• Multiple choice questions
• Multiple attempts are allowed

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1.

[ Java ]

What is the output of the following class?public class Test{
    public Test() {
         int x = 5;
         return x;
    }
  public static void main(String[] args){
       System.out.println(new Test());
   }
}

compile time error

run time error

5

x

2.

[ Java ]

Which of the following declaration is correct?

class A extends ClassA, ClassB implements InterfaceA, InterfaceB

class A extends ClassB implements InterfaceA, InterfaceB

class A implements InterfaceA, InterfaceB extends ClassA

class A implements InterfaceA extends ClassA

3.

[ Java ]

Which member of an abstract class can be abstract?

Private methods

Protected methods

Static methods

Constructors

4.

[ Java ]

Which of the following code snippets would compile successfully?

int i = 1L + 2;

int i = 1L + 2L;

long l = 1L + 2;

float = 3.14;

5.

[ Java ]

What is @Override annotation?

It makes the method virtual

It stops overriding the method

It causes the compiler to check the method exists in a superclass

It forces the subclass to override the method

6.

[ Java ]

In the following code. Who has access to member num?package car;
public class Audi {
   int num;
}

Only class Audi and subclasses of Audi within any package

Class Audi, subclass of Audi defined in package car, and other classes in package car

Class Audi, subclasses of Audi defined in any package, and other classes in package car

Only class Audi

7.

[ Java ]

What is the command to run a JAR file application?

$ java -run application.jar

$ java -start application.jar

$ java -jar application.jar

$ jar -java application.jar

8.

[ Java ]

Which of the following statements is true?

An abstract class can have both abstract and non-abstract methods

All methods in an Abstract class need to be abstract

An abstract class can declare a static abstract method

An abstract class can have abstract private methods

9.

[ Java ]

There is a class with private constructors only. How can we provide a way to create instance of this class?

There is no way to create instance of this class.

Create a static method within the class that will call one of the private contructors

class will not compile

Extend this class and make contructor public

10.

[ Java ]

What is correct variable type for the result?... variable = 5 + 0.11;

float

long

integer

double

11.

[ Java ]

What is the output for the below code?public class Test{
    public static void main(String[] args){
            Integer i = Integer.valueOf("1");
            if(i.toString()=="1")
               System.out.println("Equal");
            else
                System.out.println("Not Equal");
     }
}

Not Equal

Syntax Error

Equal

Compile-Time Error

12.

[ Java ]

Create a set of strings and add the string "def" three times to this set, then remove an "def" string. What will happen when size() method is called on this set?

compile time error

returns 2

returns 0

IllegalStateException

13.

[ Java ]

What is the difference between Vector and ArrayList?

Vector is dynamically resized but ArrayList is manually resized

Vector is synchronized but ArrayList is not

ArrayList uses Array as its data structure but Vector used vector

ArrayList is synchronized but Vector is not

14.

[ Java ]

What happens when we try to add the same element twice to a Set?

Compile time error

Element is not added and add() method returns false

Element is added successfully

IllegalStateException

15.

[ Java ]

Which Java declaration will return syntax error?

List>var;

Double[] var = {1.0,2.0,3.0,4.0};

List var;

float var = 4.3f;

16.

[ Java ]

When is an object's finalize method called?

When last reference to object is destroyed or out of scope

When the object needs to release any resource it holds

Right before the object is garbage collected

When System.gc() is called

17.

[ Java ]

Which one these is a valid keyword in Java?

string

unsigned

Float

interface

18.

[ Java ]

Which of the following code snippets will compile?

None of the snippets will compile

List a = new ArrayList();

List a = new ArrayList();

List a = new ArrayList();

19.

[ Java ]

Which Java class provides variables local to each thread?

Thread

ThreadLocal

Runnable

LocalThread

20.

[ Java ]

What modifier is used to provide access to a method within the class and all the extending classes?

default

public

private

protected

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