JAVA Introduction

Question 1

JVM Stands for

Answer 1

Java virtual machine

Question 2

JRE Stands for

Answer 2

Java runtime environment

Question 3

JDK Stands for

Answer 3

java development kit

Question 4

JVM only understands ….

Answer 4

bytecode

Question 5

java files are compiled into ….

Answer 5

bytecode

Question 6

JRE provides the ….,….., and other components to run the applets

Answer 6

libraries and java virtual machine

Question 7

true or false: JRE contains tools and utilities such as compilers and debugging applets and applications.

Answer 7

false

Question 8

JDK contains …..

Answer 8

everything in jre plus tools and compilers and debuggers necessary for developing applets and applications

Question 9

Properties of Java ? (7)

Answer 9

• Object oriented
• Interpreted
• portable
• secure and robust
• multi threaded
• garbage collector
• no support for multiple inheritance

Question 10

java file is compiled to …

Answer 10

class file (bytecode)

Question 11

memory in java is allocated (dynamically- manually - statically )

Answer 11

dynamically

Question 12

deallocation is process of

Answer 12

removing the objects that are no longer referenced from memory

Question 13

garbage collector helps prevent ….

Answer 13

memory leaks

Question 14

object oriented programming is a ….

Answer 14

programming paradigm based on the concept of objects

Question 15

each object contains data in form of ….

Answer 15

fields , methods

Question 16

object constitutes the

Answer 16

building blocks of the program

Question 17

true or false : classes can’t form a hierarchy

Answer 17

false , they can

Question 18

Principles of object oriented programming

Answer 18

Encapsulation
abstraction
inheritance
polymorphism

Question 19

encapsulation is

Answer 19

process of combining data and methods into a single unit called a class

Question 20

encapsulation helps in

Answer 20

keep data both safe from outside interference

allows to expose only necessary data

Question 21

encapsulation can be controlled via

Answer 21

access modifiers private public and protected

Question 22

abstraction is

Answer 22

to hide complexity of the program by hiding the unnecessary detail from the user can be achieved by using classes

Question 23

inheritance allows

Answer 23

creating hierarchy of related classes

allows code reusability

Question 24

Polymorphism is

Answer 24

same concept can have different meaning in different contexts

Question 25

polymorphism has two forms

Answer 25

overloading and overriding

Question 26

overloading is

Answer 26

same method name with different parameters

Question 27

overriding is

Answer 27

same name, same parameter , same return type but different body

Question 28

branching forms

Answer 28

if-else and switch

Question 29

loops comes in

Answer 29

for , while, do-while, foreach

Question 30

loop control are

Answer 30

break | continue

Question 31

for each is used to

Answer 31

traverse an array or a collection in java

Question 32

True or false : for each loop has no loop variable

Answer 32

true

Question 33

True or false: break and continue statement is limited to 1 per loop

Answer 33

true

Question 34

T or F: arrays has a fixed size

Answer 34

true

Question 35

if an array position is not initialized it is ....

Answer 35

NULL

Question 36

an object is an ... of a specific class

Answer 36

instance

Question 37

t or f: objects reserves a place in memory

Answer 37

true

Question 38

new is a keyword that

Answer 38

instantiate the object

Question 39

if an object is not instantiated it is

Answer 39

null

Question 40

to access fields we used ... operator

Answer 40

dot operator

Question 41

each class must have ....

Answer 41

at least one constructor

Question 42

t or f: a constructor has a return value

Answer 42

false

Question 43

constructor name must be ...

Answer 43

the same as the class name

Question 44

if no constructor is defined the complier creates one with no parameter called ...

Answer 44

default constructor

Question 45

default constructor intialize the values with ... for numeric ... for booleans .... for object references

Answer 45

zero, false, null

Question 46

to call the parent class constructor we use

Answer 46

super();

Question 47

UML is

Answer 47

unified modeling language object oriented modeling language

Question 48

uml is represented by a ..... usually divided into three sections which are ....

Answer 48

- class name - attributes (fields) - operations (methods)

Question 49

in uml + , - , # denotes ?

Answer 49

public , private, protected

Question 50

relationship types in uml

Answer 50

are inheritance , and association

Question 51

inheritance represents ....

Answer 51

a hierarchy between classes

Question 52

association represents ...

Answer 52

a relationships between objects

Question 53

a package is a container ...

Answer 53

for all related classes

Question 54

access modifier none (Package local) is visible in ....

Answer 54

only within the same package

Question 55

private is only accessible within ...

Answer 55

the same class

Question 56

protected can be accessed within...

Answer 56

the same package and subclass

Question 57

public can be accessed ...

Answer 57

anywhere

Question 58

static modifier is

Answer 58

for the entire class and not for a specific object

Question 59

final means its value

Answer 59

cant be changed

Question 60

private is visible in the same package class?

Answer 60

no

Question 61

private is visible inside the class

Answer 61

yes

Question 62

private is visible inside the same package sub class?

Answer 62

no

Question 63

protected is visible inside other package class?

Answer 63

no

Question 64

protected is visible inside same package class?

Answer 64

yes

Question 65

package local can be accessed from other package class

Answer 65

no

Question 66

package local can be accessed from other package sub-class

Answer 66

no

Question 67

protected modifier is visible in other package class

Answer 67

no

Question 68

static modifier can be accessed via ...

Answer 68

class name

Question 69

non-static can only be accessed via ...

Answer 69

object name

Question 70

final must be initialized when .... or in ...

Answer 70

declared, constructor