Java Quiz on Module 1 & 2

Can we create an instance of Enum outside of Enum itself?

• True

• False

• Enum is not a class type

• None of the above

Answer explanation

No, instances of Enum cannot be created outside of Enum boundary, because Enum does not have a public constructor.

What will be the output of the following Java code?

enum Season

{

WINTER, SPRING, SUMMER, FALL

};

System.out.println(Season.WINTER.ordinal());

• 0

• 1

• 2

• 3

Answer explanation

ordinal() method provides number to the variables defined in Enum.

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

class A

{

 

}

 

enum Enums extends A

{

ABC, BCD, CDE, DEF;

}

• Runtime Error

• Compilation Error

• It runs successfully

• EnumNotDefined Exception

Answer explanation

Enum types cannot extend class.

Consider the following code inside TestEnum.java file

enum Branches {

Delhi(2),Chennai(3),Mumbai(3),Bangalore(5);

private int noofOffice;

private Branches(int noofOffice){

this.noofOffice=noofOffice;

}

public int getNoofOffice(){

return noofOffice;

}

}

class TestEnum{

public static void main(String[] args) {

System.out.println(Branches.Bangalore.getNoofOffice());

}

}

What will happen after compilation of the code?

• Compilation error "enum constructor cannot be private

• Compilation error" Cannot have variables in enum"

• Code will compile sucessfully

• Compilation error "enum object should be created with new keyword"

Choose a correct statement about Autoboxing in Java?

• Boxing is the process of converting a primitive data to its equivalent Wrapper class type

• Unboxing is the process of converting a Wrapper class object to its equivalent primitive data type

• Autoboxing is the process of converting Primitive data type to Wrapper Object type automatically. Auto-Unboxing is the process of converting Wrapper type object to Primitive type automatically.

• All the above

Which does autoboxing or unboxing in Java?

• Compiler

• Runtime

• Third party tools

• None

Choose the right statement which does autoboxing in Java?

• Integer temperature1 = 100;

• int temperature2 = 101;

• Integer temperature1 = 100; int temperature2 = 101;

• All the above

Answer explanation

As part of auto-boxing, an INT number is converted to INTEGER object automatically.

What is the output of the below java code with autoboxing?

public class AutoBoxingTest2 {

static void show(int reading)

{

System.out.println("Reading: " + reading);

}

public static void main(String[] args) {

Integer a = Integer.valueOf(10);

show(a); }

}

• Reading: 0

• Reading: 10

• Compiler error

• None

Which version of Java introduced annotation?

• Java 5

• Java 6

• Java 7

• Java 8

Which of the following is not pre-defined annotation in Java?

• @Deprecated

• @Overriden

• @SafeVarags

• @FunctionInterface

Answer explanation

@Overriden is not a pre defined annotation in Java. @Depricated, @Override, @SuppressWarnings, @SafeVarags and @FunctionInterface are the pre defined annotations.