1. Core Java

8/17/2019 1. Core Java

1/177

CORE JAVA

Rajeev Gupta

MTech CS

8/17/2019 1. Core Java

2/177

Contents at a glance

[email protected]

Java An Introduction

Basic Java Constructs and ata T!pes and arra!

OO Introduction

Class o"ject and related topics

Inheritance

#inal $A"stract Classes and inter%ace

String class$ i&&uta"ilit!$ inner classes

E'ceptions (andling$ assertions

Strea&s and Input)output #iles$ seriali*ation Java Thread

Java Collections

8/17/2019 1. Core Java

3/177

a!+,

[email protected]

Session-1

Introduction to Java

What is Java,Why Java?

JDK,JRE and JVM discussion Installing JDK, eclipse

Hello World application

Procedural Prograing

I!""else,s#itch, looping

$rray

E%aples

Session-2

&'(ect &riented

&'(ect, class, Encapsulation,

$'straction,

Inheritence,

Polyorphis,essage

passing

) concepts only, ipleentation on day *+

8/17/2019 1. Core Java

4/177

a!+.

[email protected]

Session-1

lass and o'(ects

reating lasses

Ipleenting Methods

&'(ect- state, identity and 'ehaviour

onstructors- de!ault, paraeteri.ed and copy

Instance varia'le, static varia'le and local

varia'le

Initiali.ation 'loc/

0tatic ethod and applications

/ac0ages and visi"ilit! &odi1er2 pu"lic$protected$ private and de%ault

Session-2Inheritance

1ype o! inheritance, diaond pro'le

Instance&! operator

2inal

2inal varia'le, !inal ethod , !inal class

$cess control- pu'lic,

private,protected and de!ault

Pac/ages

$'stract class

Inter!ace

Polyorphis&verloading

&verriding

1ype o! relationship '# o'(ects

I03$, H$03$, 40E3$

8/17/2019 1. Core Java

5/177

a!+3

[email protected]

Session-1

0tring class- Iuta'ility and usages,

string'uilder and string'u!!er

Wrapper classes and usages

Java 5 6anguage 2eatures )I+-

$uto7o%ing and 4n'o%ing, Enhanced 2or

loop, Varargs, 0tatic Iport, Enus

Inner classes

Regular inner class, ethod local inner class,

annonyous inner class

Session-2

E%ception handling

1ry, catch, thro#, thro#s,

!inally

hec/ed and

4nchec/ed e%ception

4ser de!ined e%ceptions

Rules !or &verloading8&verriding8onstructor

thro#ing e%ceptions

Rethro#ing e%ceptions

E%ception haining

assertions

8/17/2019 1. Core Java

6/177

8/17/2019 1. Core Java

7/177

a!+5

[email protected]

Session-1

ollections 2rae#or/

6ist, Map, 0et usages introduction

4sages $rray6ist, 6in/ed6ist, HashMap,

1reeMap, Hash0et

opara'le, oparator inter!ace

ipleentation

4ser de!ine /ey in HashMap

Session-2

Java 5 6anguage 2eatures II

;enerics$nnotations

ase study using collection, 2ile

8/17/2019 1. Core Java

8/177

A6+,

[email protected]

8/17/2019 1. Core Java

9/177

Session+,

[email protected]

Introduction to Java What is Java,Why Java?

JDK,JRE and JVM discussion

Installing JDK, eclipse Hello World application

Procedural Prograing I!""else,s#itch, looping

$rray

E%aples

8/17/2019 1. Core Java

10/177

7hat is Java8

[email protected]

Java

8/17/2019 1. Core Java

11/177

(o9 Sun de1ne Java8

[email protected]

0iple

&'(ect &riented

Porta'le

$rchitecture >eutral

Distri'uted Multi3threaded

Ro'ust, 0ecure80a!e

Interpreted

High Per!orance

Dynaic prograing language8plat!or"

8/17/2019 1. Core Java

12/177

Java Platform

[email protected]

8/17/2019 1. Core Java

13/177

8/17/2019 1. Core Java

14/177

So&e co&&on "u**9ords

[email protected]

JDK

Java developent /it, developer need it

7yte ode

Highly optii.e instruction set, designed to run on JVM

Plat!or independent JRE

Java Runtie environent, reate an instance JVM, ust 'e there on

deployent achine"

Plat!or dependent

JVM Java Virtual Machine JVM

Pic/ 'yte code and e%ecute on client achine

Plat!or dependentG

8/17/2019 1. Core Java

15/177

[email protected]

8/17/2019 1. Core Java

16/177

:nderstanding JVM

[email protected]

8/17/2019 1. Core Java

17/177

(ello 7orld

[email protected]

;a" set+up Java ,

8/17/2019 1. Core Java

18/177

Anal!sis o% (ello 7orld

[email protected]

8/17/2019 1. Core Java

19/177

Java /rogra& Structure

[email protected]

ocu&entation Section

/ac0age State&ent

I&port State&ents

Inter%ace State&ents

Class eclarations

Main Method Class

8/17/2019 1. Core Java

20/177

Java ata T!pe

[email protected]

. t!pe /ri&itive data t!pe

Re%erence data t!pe

8/17/2019 1. Core Java

21/177

/ri&itive data t!pe

[email protected]

"oolean either true o% %alse

char ,> "it :nicode ,+"it integer ?signed@

int 3.+"it integer ?signed@

long >4+"it integer ?singed@

oat 3.+"it oating point ?IEEE =54+,FD5@

dou"le >4+"it oating point ?IEEE =54+,FD5@

Java uses :nicode to represent characters internall!

8/17/2019 1. Core Java

22/177

/rocedural /rogra&&ing

[email protected]

i%

8/17/2019 1. Core Java

23/177

Arra!

[email protected]

One i&ensional arra!

int 'KLne9 intK5L

(o9 Java arra! diNerent %ro&

C)CHH arra!8

8/17/2019 1. Core Java

24/177

Session+.

[email protected]

O"ject Oriented Concepts

O"ject$ class

Basic principles o% OO Encapsulation

A"straction

&odularit!

Inheritance) (ierarch! /ol!&orphis&$ &essage passing

8/17/2019 1. Core Java

25/177

O"ject technologies

[email protected]

8/17/2019 1. Core Java

26/177

7hat is an O"ject8

[email protected]

8/17/2019 1. Core Java

27/177

Class

[email protected]

8/17/2019 1. Core Java

28/177

Classes and O"ject

[email protected]

8/17/2019 1. Core Java

29/177

Basic principles o% OO

[email protected]

8/17/2019 1. Core Java

30/177

A"straction

[email protected]

8/17/2019 1. Core Java

31/177

Encapsulation

[email protected]

8/17/2019 1. Core Java

32/177

Modularit!

[email protected]

8/17/2019 1. Core Java

33/177

(ierarch!

[email protected]

8/17/2019 1. Core Java

34/177

A "it a"out :M; diagra&

[email protected]

:M; .

8/17/2019 1. Core Java

35/177

A6+.

[email protected]

8/17/2019 1. Core Java

36/177

Session+,

[email protected]

Class and o"jects Creating Classes and o"ject

O"ject2 state$ identit! and "ehaviour

Constructors2 de%ault$ para&eteri*ed and cop!

eed o% this $ Constructor chaining

Instance varia"le$ static varia"le and localvaria"le

Initiali*ation "loc0

Scanner and print%

/ara&eter passing in Java Call "! value ) call "! re%erence

7h t i id

8/17/2019 1. Core Java

37/177

7hat can goes inside anclass8

[email protected]

8/17/2019 1. Core Java

38/177

Creating Classes and object

[email protected]

8/17/2019 1. Core Java

39/177

Correct 9a!8

[email protected]

8/17/2019 1. Core Java

40/177

Constructors: default, parameterized and cop

[email protected]

Initiali*e state o% the o"ject Special &ethod have sa&e

na&e as that o% class

Cant return an!thing

Can onl! "e called once %or an

o"ject

Can "e private

Cant "e static

Can overloaded "ut cantoverridden

Three t!pe o% constructors

e%ault$

/ara&eteri*ed and

Cop! constructor

8/17/2019 1. Core Java

41/177

eed o% this 8

[email protected]

7hich id assigned to9hich id8

this is an re%erence tothe current o"ject reQuiredto diNerentiate local

varia"les 9ith instancevaria"les

Re%er ne't slide

this used to resolve

8/17/2019 1. Core Java

42/177

this used to resolvecon%usion

[email protected]

8/17/2019 1. Core Java

43/177

this 2 Constructor chaining8

[email protected]

Calling oneconstructor %ro&another 8

8/17/2019 1. Core Java

44/177

Static &ethod)varia"le

[email protected]

Instance varia"le Uper o"ject9hile static varia"le are per class

Initiali*e and de1ne "e%ore an!o"jects

Most suita"le %or counter %oro"ject

Static &ethod can onl! accessstatic data o% the class

#or calling static &ethod 9e dontneed an o"ject o% that class

o9 guess 9h! &ain 9as static8

8/17/2019 1. Core Java

45/177

:sing static data

8/17/2019 1. Core Java

46/177

!nitialization bloc"

[email protected]

7e can putrepeatedconstructor code

in an Initiali*ation"loc0

Static Initiali*ation"loc0 runs "e%orean! constructorand runs onl!

once

8/17/2019 1. Core Java

47/177

Initiali*ation "loc0

[email protected]

8/17/2019 1. Core Java

48/177

8/17/2019 1. Core Java

49/177

Java #oundation /ac0ages

[email protected]

Java provides a large nu&"er o% classes groped intodiNerent pac0ages "ased on their %unctionalit!<

The si' %oundation Java pac0ages are2 java

8/17/2019 1. Core Java

50/177

Visi"ilit! Modi1ers

[email protected]

#or instance varia"le and &ethods /u"lic

/rotected

e%ault ?pac0age level@ /rivate

#or classes

/u"lic and de%ault

8/17/2019 1. Core Java

51/177

Visi"ilit! Modi1ers

[email protected]

class A has de%ault visi"ilit!

hence can access in the sa&epac0age onl!<

Ma0e class A pu"lic$ thenaccess it<

/rotected data can access in thesa&e pac0age and all thesu"classes in other pac0agesprovide class itse% is pu"lic

8/17/2019 1. Core Java

52/177

Visi"ilit! Modi1ers

[email protected]

Accessible to: public protected Package

(default)

private

Same Class Yes Yes Yes Yes

Class in package Yes Yes Yes No

Subclass in

different package

Yes Yes No No

Non-subclassdifferent package

Yes No No No

8/17/2019 1. Core Java

53/177

7ant to accept para&eter %ro& user8

[email protected]

java

8/17/2019 1. Core Java

54/177

Call "! value

[email protected]

Java support call "! value

The value changes in %unction is not going to reected inthe &ain<

8/17/2019 1. Core Java

55/177

Call "! re%erence

[email protected]

Java dont support call "! re%erence<

7hen !ou pass an o"ject in an &ethod cop! o% re%erence is passed so that 9e can &utate thestate o% the o"ject "ut cant delete original o"ject itsel%

8/17/2019 1. Core Java

56/177

Session+.

[email protected]

Inheritance

T!pe o% inheritance$ dia&ond pro"le&

InstanceO% operator

#inal

#inal varia"le$ 1nal &ethod $ 1nal class Acess control2 pu"lic$ private$protected and de%ault

/ac0ages

A"stract class

Inter%ace

/ol!&orphis&

Overloading

Overriding

8/17/2019 1. Core Java

57/177

Inheritance

[email protected]

Inheritance is theinclusion ofbehaviour (i.e.methods) and state(i.e. variables) of a

base class in aderived class so thatthe! are accessi"le inthat derived class<

code reusability.

Subclass and Superclass concept

8/17/2019 1. Core Java

58/177

ia&ond /ro"le&8

[email protected]

(ierarch! inheritance can leads to poor design

8/17/2019 1. Core Java

59/177

Inheritance e'a&ple

[email protected]

:se e'tends 0e!9ord

:se super to pass valuesto "ase class constructor<

8/17/2019 1. Core Java

60/177

Overloading

[email protected]

Overloading deals 9ith &ultiple &ethods in the sa&e class 9ith the sa&e na&e "utdiNerent &ethod signatures<

Both the a"ove &ethods have the sa&e &ethod na&es "ut diNerent &ethodsignatures$ 9hich &ean the &ethods are overloaded<

Overloading lets you defne the same operation in

dierent ways or dierent data.

Constructor can be overloaded

Be careul o overloading ambiguity

*Overloading in case o var-arg and rapper ob!ects"

8/17/2019 1. Core Java

61/177

Overriding

[email protected]

Overriding deals 9ith t9o &ethods$ one in the parent class andthe other one in the child class and has the sa&e na&e andsignatures<

Both the a"ove &ethods have the sa&e &ethod na&es and the

signatures "ut the &ethod in the su"class MyClass overrides the&ethod in the superclass BaseClass

Overriding lets !ou de1ne the same operation in dierentways or dierent ob!ect types.

8/17/2019 1. Core Java

62/177

/ol!&orphis&

[email protected]

/ol!&orphis&&an! %or&s o% onethings

Substitutability

Overriding Polymorphism means the ability of a

single variable of a given type to be

used to reference objects of diNerentt!pes$ and auto&aticall! call the &ethodthat is speci1c to the t!pe o% o"ject thevaria"le re%erences<

l hi

8/17/2019 1. Core Java

63/177

/ol!&orphis&

[email protected]

Ever! ani&al sound "utdiNerentl!

7e 9ant to have /ointer o% Ani&alclass assigned "! o"ject o%

derived class

l

8/17/2019 1. Core Java

64/177

E'a&ple

[email protected]

d % " l 8

8/17/2019 1. Core Java

65/177

eed o% a"stract class8

[email protected]

Sound? @ &ethod o%Ani&al class dont &a0ean! sense i

8/17/2019 1. Core Java

66/177

A"stract class

[email protected]

I% an class have atleast one a"stract&ethod it should "edeclare a"stract class<

So&e ti&e i% 9e 9antto stop a progra&&erto create o"ject o%so&e class

Class has so&e de%ault%unctionalit! that can"e used as it is<

Can e'tends onl! one

a"stract class

A" t t l

8/17/2019 1. Core Java

67/177

A"stract class use cases

[email protected]

7ant to have so&e de%ault %unctionalit! %ro&"ase class and class have so&e a"stract%unctionalit! that cant "e de1ne at that &o&ent<

ont 9ant to allo9 a progra&&er to createo"ject o% an class as it is too generic

Inter%ace vs< a"stract class

M l

8/17/2019 1. Core Java

68/177

More e'a&ple

[email protected]

#i l

8/17/2019 1. Core Java

69/177

#inal

[email protected]

7hat is the &eaning o% 1nal So&ething that can not "e change

1nal #inal &ethod argu&ents

Cant "e change inside the &ethod

#inal varia"le Beco&e constant$ once assigned then cant "e changed

#inal &ethod Cant overridden

#inal class Can not inherited ?illing e'tendi"ilit! @

Can "e reuse

So&e e'a&ples<

#i l l

8/17/2019 1. Core Java

70/177

#inal class

[email protected]

#inal class cant "e su"class i

8/17/2019 1. Core Java

71/177

#inal Method

[email protected]

#inal Method Cant overridden Class containing 1nal &ethod can "e

e'tended

illing su"stituta"ilit!

I t % 8

8/17/2019 1. Core Java

72/177

Inter%ace8

[email protected]

Inter%ace 2 Contract "9 t9o parties Inter%ace &ethod

Onl! declaration

o &ethod de1nition

Inter%ace varia"le /u"lic static and 1nal constant

Its ho9 java support glo"al constant

Brea0 the hierarch!

Solve dia&ond pro"le&

Call"ac0 in Java

So&e E'a&ple <

I t % 8

8/17/2019 1. Core Java

73/177

Inter%ace8

[email protected]

Rules All inter%ace &ethods are al9a!s pu"lic and a"stract$ 9hether 9e sa! it

or not<

Varia"le declared inside inter%ace are al9a!s pu"lic static and 1nal

Inter%ace &ethod cant "e static or 1nal

Inter%ace cant have constructor An inter%ace can e'tends other inter%ace

Can "e used pol!&orphicall!

An class i&ple&enting an inter%ace &ust i&ple&ent all o% its &ethodother9ise it need to declare itsel% as an a"stract class

I&ple&enting an

8/17/2019 1. Core Java

74/177

p e e g ainter%ace

[email protected]

8/17/2019 1. Core Java

75/177

i Ri idit i i #l i"ilit

8/17/2019 1. Core Java

76/177

ecreasing Rigidit!

8/17/2019 1. Core Java

77/177

!p po"jects

[email protected]

:SE+A (AS+A

IS+A ?Most costl! 8 @

A;7A6S GO #OR ;OOSE CO:/;IG A

(IG( CO(ESIO

But (O78

IS A VS (AS A

8/17/2019 1. Core Java

78/177

IS+A VS (AS+A

[email protected]

8/17/2019 1. Core Java

79/177

A6+3

[email protected]

0 i

8/17/2019 1. Core Java

80/177

0ession3

[email protected]

0tring class Iuta'ility and usages,

string'uilder and string'u!!er

Wrapper classes and usages

Java 5 6anguage 2eatures )I+-

$uto7o%ing and 4n'o%ing Enhanced 2or loop

Varargs

0tatic Iport

Enus

Inner classes

Regular inner class

ethod local inner class

anonyous inner class

String

8/17/2019 1. Core Java

81/177

String

[email protected]

I&&uta"le i

8/17/2019 1. Core Java

82/177

I&&uta"ilit!

[email protected]

!mmutabilit means something that cannot be changed.

#trings are immutable in Java. $hat does this mean%

String literals are ver! heavil! used in applications andthe! also occup! a lot o% &e&or!<

There%ore %or eWcient &e&or! &anage&ent$ all the stringsare created and 0ept "! the JVM in a place called stringpool ?9hich is part o% Method Area@<

Gar"age collector does not co&e into string pool<

(o9 does this save &e&or!8

So&e co&&on string

8/17/2019 1. Core Java

83/177

g&ethods

[email protected]

charAt?@ Returns the character located at the speci1ed inde'

concat?@ Appends one String to the end o% another ? XHX also 9or0s@

eQualsIgnoreCase?@ eter&ines the eQualit! o% t9o Strings$ ignoring case

length?@

Returns the nu&"er o% characters in a String

replace?@ Replaces occurrences o% a character 9ith a ne9 character

su"string?@

Returns a part o% a String

to;o9erCase?@ Returns a String 9ith uppercase characters converted

toString?@ Returns the value o% a String

to:pperCase?@ Returns a String 9ith lo9ercase characters converted

tri&?@ Re&oves 9hitespace %ro& the ends o% a String

String co&parison

8/17/2019 1. Core Java

84/177

String co&parison

[email protected]

T9o string should never "e chec0ed %or eQualit! using operator 7(68

Al9a!s use eQuals? @ &ethod<

String s,india

String s.pa0i

i%?s,

8/17/2019 1. Core Java

85/177

7rapper classes

[email protected]

(elps treating pri&itive data as an o"ject But 9h! 9e should convert pri&itive to o"jects8

7e cant store pri&itive in java collections

O"ject have properties and &ethods

(ave diNerent "ehavior 9hen passing as &ethodargu&ent

Eight 9rapper %or eight pri&itive Integer$ #loat$ ou"le$ Character$ Boolean etc

Integer itne9 Integer?33@

int te&pit

8/17/2019 1. Core Java

86/177

Bo'ing ) :n"o'ing Java ,

8/17/2019 1. Core Java

87/177

Enhanced #or loop

8/17/2019 1. Core Java

88/177

[email protected]

/rovide eas! looping construct to loop through arra!and collections

8/17/2019 1. Core Java

89/177

Static I&port

8/17/2019 1. Core Java

90/177

Static I&port

[email protected]

(and! %eature in Java ,

8/17/2019 1. Core Java

91/177

Enu&s

[email protected]

Enu& is a special t!pe o% classes< enu& t!pe used to put restriction on the instance values

Inner classes

8/17/2019 1. Core Java

92/177

Inner classes

[email protected]

Inner class8 A class de1ned inside

another class<

7h! to de1ne inner classes

Inner classes

Top level inner class Method local inner

class

Anon!&ous Innerclass

Method local

argu&ent inner class

Static inner classes

Top level inner class

8/17/2019 1. Core Java

93/177

Top level inner class

[email protected]

on static inner class o"ject canYt "e created 9ithout outerclass instance

All the private data o% outer class is availa"le to inner class

on static inner class canYt have static &e&"ers

Method local inner class

8/17/2019 1. Core Java

94/177

Method local inner class

[email protected]

Class de1ne inside an &ethod Can not access local data de1ne inside &ethod

eclare local data 1nal to access it

Anon!&ous Inner class

8/17/2019 1. Core Java

95/177

Anon!&ous Inner class

[email protected]

A 9a! to i&ple&ent pol!&orphis& On the !

Session+.

8/17/2019 1. Core Java

96/177

Session+.

[email protected]

E'ception handling Tr!$ catch$ thro9$ thro9s$ 1nall!

Chec0ed and :nchec0ed e'ception

:ser de1ned e'ceptions Rule %or Overloading) Overriding in case o%

&ethod thro9ing e'ceptions

Assertions

7hat is E'ception8

8/17/2019 1. Core Java

97/177

7hat is E'ception8

[email protected]

An e'ception is an a"nor&al condition that arises 9hilerunning a progra&<

E'a&ples2

Atte&pt to divide an integer "! *ero causes an e'ception to "e thro9n at run ti&e<

Atte&pt to call a &ethod using a re%erence that is null< Atte&pting to open a none'istent 1le %or reading<

JVM running out o% &e&or!<

E'ception handling do not correct a"nor&al condition

rather it &a0e our progra& ro"ust i

8/17/2019 1. Core Java

98/177

T!pe o% e'ceptions

[email protected]

,< :nchec0ed E'ception

Also called Runti&e E'ceptions.< Chec0ed E'ception

Also called Co&pile ti&eE'ceptions

3< Error Should not to "e handled "!

progra&&er

8/17/2019 1. Core Java

99/177

E'ceptions and their

8/17/2019 1. Core Java

100/177

(andling

[email protected]

7hen the JVM encounters an error such as divide "!*ero$ it creates an e'ception o"ject and thro9s it U asa noti1cation that an error has occurred<

I% the e'ception o"ject is not caught and handledproperl!$ the interpreter 9ill displa! an error andter&inate the progra&<

I% 9e 9ant the progra& to continue 9ith e'ecution o%the re&aining code$ then 9e should tr! to catch thee'ception o"ject thro9n "! the error condition andthen ta0e appropriate corrective actions< This tas0 is0no9n as exception handling<

Co&&on Java E'ceptions

8/17/2019 1. Core Java

101/177

Co&&on Java E'ceptions

[email protected]

Arith&eticE'ception Arra!Inde'OutO%BoundE'ception Arra!StoreE'ception #ileot#oundE'ception

IOE'ception U general I)O %ailure ull/ointerE'ception U re%erencing a null o"ject OutO%Me&or!Error Securit!E'ception U 9hen applet tries to per%or& an

action not allo9ed "! the "ro9sers securit! setting< Stac0Overo9Error StringInde'OutO%BoundE'ception

Rules %or thro9ing e'ception %ro&idd th d

8/17/2019 1. Core Java

102/177

overridden &ethods

[email protected]

Rules %or thro9ing e'ception %ro&t t

8/17/2019 1. Core Java

103/177

constructors

[email protected]

Rules %or thro9ing e'ception %ro&l d d d th th d

8/17/2019 1. Core Java

104/177

overloaded and other &ethods

[email protected]

8/17/2019 1. Core Java

105/177

A6+4

[email protected]

Session+,

8/17/2019 1. Core Java

106/177

Session ,

[email protected]

Char and "!te oriented strea&s BuNeredReader and BuNered7riter

#ile handling

O"ject Seriali*ation

KO"jectInputStrea& ) O"jectOutputStrea&L

Strea&

8/17/2019 1. Core Java

107/177

Strea&

[email protected]

Strea& is an a"straction that either produces or consu&es in%or&ation< A strea& is lin0ed to a ph!sical device "! the Java I)O s!ste&<

All strea&s "ehave in the sa&e &anner$ even i% the actual ph!sicaldevices to 9hich the! are lin0ed diNer<

. t!pes o% strea&s2

"!te 2 %or "inra! data All "!te strea& class are li0e ZZZZZZZZStrea&

character2 %or te't data

All char strea& class are li0e ZZZZZZZZReader) ZZZZZZ7riter

8/17/2019 1. Core Java

108/177

[email protected]

So&e i&portant classes% j i

8/17/2019 1. Core Java

109/177

%or& java

8/17/2019 1. Core Java

110/177

S!ste& class in java

[email protected]

S!ste& class de1ned in java

8/17/2019 1. Core Java

111/177

[email protected]

Reading %or& console BuNeredReader "rne9 BuNeredReader?ne9 InputStrea&Reader?S!ste&

8/17/2019 1. Core Java

112/177

e

[email protected]

#ile a"straction thatrepresent 1le anddirectories #ile %ne9 #ile?X

8/17/2019 1. Core Java

113/177

[email protected]

Storing the state o% the o"ject on a 1le along so&e &etadata

8/17/2019 1. Core Java

114/177

Seriali*ation

[email protected]

The state o% the o"ject %ro& heap is suc0ed and 9rittenalong 9ith so&e &eta data in an 1le<

e+ Seriali*ation

8/17/2019 1. Core Java

115/177

[email protected]

7hen an o"ject is de+seriali*ed$ the JVM atte&pts to "ringo"ject "ac0 to the li%e "! &a0ing an ne9 o"ject on theheap that have the sa&e state as original o"ject

Transient varia"le dont get saved during seriali*ationhence co&e 9ith null

(ello 9orld E'a&ple

8/17/2019 1. Core Java

116/177

p

[email protected]

8/17/2019 1. Core Java

117/177

7hat is threads8 ;7/

8/17/2019 1. Core Java

118/177

[email protected]

Basic %unda&entals

8/17/2019 1. Core Java

119/177

[email protected]

Thread2 class in java

8/17/2019 1. Core Java

120/177

Java8

[email protected]

I&ple&ents Runna"le inter%ace E'tending Thread class

8/17/2019 1. Core Java

121/177

!

[email protected]

I% a thread is "loc0ed? put to sleep@ speci1edno o% &s should e'pire

I% thread 9aiting %or IO

that &ust "e over

8/17/2019 1. Core Java

122/177

J g

[email protected]

Thread?@ construct ne9 thread

void run?@ &ust "e overriden

void start?@

start thread call run &ethod static void sleep?long &s@

put currentl! e'ecuting thread to sleep %or speci1ed no o% &illisecond

"oolean isAlive?@ return true i% thread is started "ut not e'pired

void stop?@ void suspend?@ and void resu&e?@

Suspend thread e'ecution<

Java

8/17/2019 1. Core Java

123/177

[email protected]

void join?long &s@

Main thread 7ait %or speci1ed thread to co&plete ortill speci1ed ti&e is not over

void join?@ Main thread 7ait %or speci1ed thread to co&plete

static "oolean interrupted?@

"oolean isInterrupted?@

void interrupt?@ Send interrupt reQuest to a thread

8/17/2019 1. Core Java

124/177

:nderstanding join?@&ethod

8/17/2019 1. Core Java

125/177

&ethod

[email protected]

Chec,ing thread priorities

8/17/2019 1. Core Java

126/177

[email protected]

5nderstanding thread snchronization

8/17/2019 1. Core Java

127/177

[email protected]

S!nchroni*ation

8/17/2019 1. Core Java

128/177

S!nchroni*ation Mechanis& to controls the order in 9hich threads

e'ecute Co&petition vs< cooperative s!nchroni*ation

Mutual e'clusion o% threads Each s!nchroni*ed &ethod or state&ent is guarded

"! an o"ject< 7hen entering a s!nchroni*ed &ethod or

state&ent$ the o"ject 9ill "e loc0ed until the

&ethod is 1nished< 7hen the o"ject is loc0ed "! another thread$ the

current thread &ust 9ait<

[email protected]

:sing thread s!nchroni*ation

8/17/2019 1. Core Java

129/177

[email protected]

Inter thread co&&unication

8/17/2019 1. Core Java

130/177

[email protected]

Java have elegant Interprocessco&&unication using 9ait?@ noti%!?@ andnoti%!All?@ &ethods

All these &ethod de1ned 1nal in theO"ject class

Can "e onl! called %ro& a s!nchroni*edconte't

9ait?@ and noti%!?@$ noti%!All?@

8/17/2019 1. Core Java

131/177

[email protected]

9ait?@ Tells the calling thread to give up the &onitor and go

to the sleep until so&e other thread enter the sa&e&onitor and call noti%!?@

noti%!?@ 7a0es up the 1rst thread that called 9ait?@ on sa&e

o"ject

noti%!All?@ 7a0es up all the thread that called 9ait?@ on sa&e

o"ject$ highest priorit! thread is going to run 1rst

Incorrect i&ple&entation o% produce consu&er

8/17/2019 1. Core Java

132/177

[email protected]

Correct i&ple&entation o% produceconsu&er

8/17/2019 1. Core Java

133/177

[email protected]

8/17/2019 1. Core Java

134/177

A6+5

[email protected]

Session+,

8/17/2019 1. Core Java

135/177

[email protected]

Session+, O"ject class in Java

Collections #ra&e9or0

;ist$ Map$ Set usages introduction :sages

Arra!;ist$ ;in0ed;ist$ (ashMap$ TreeMap$(ashSet

Co&para"le$ Co&parator inter%acei&ple&entation

:ser de1ne 0e! in (ashMap

O"ject

8/17/2019 1. Core Java

136/177

[email protected]

O"ject is an special class in java de1ned in java

8/17/2019 1. Core Java

137/177

toString? @

8/17/2019 1. Core Java

138/177

[email protected]

I% 9e do not overridetoString?@ &ethod o% O"jectclass it print O"jectIdenti1cation nu&"er "!de%ault

7e can override it to printso&e use%ul in%or&ation<

toString?@

8/17/2019 1. Core Java

139/177

[email protected]

eQuals

8/17/2019 1. Core Java

140/177

[email protected]

7hat O)/ do !ou e'pect inthis case

O)/ 9ould "e t9o e&plo!ees are noteQuals

8/17/2019 1. Core Java

141/177

[email protected]

ont %orget R6 run

8/17/2019 1. Core Java

142/177

[email protected]

7henever !ou override eQuals?@%or an t!pe

dont %orget to override hashCode?@ &ethod hashCode?@ &a0e S eWcient

7hat hashCode does

(ashCode divide data into "uc0ets EQuals search data %ro& that "uc0et

clone?@

8/17/2019 1. Core Java

143/177

[email protected]

;ets consider an o"ject that creation is ver! co&plicated$9hat 9e can do 9e can &a0e an clone o% that o"ject anduse that

Costl! $ avoid using cloning i% possi"le$ internall! dependson seriali*ation

Must &a0e class supporting cloning "! i&ple&enting an&ar0er inter%ace ie Clonea"le

1nali*e?@

8/17/2019 1. Core Java

144/177

[email protected]

As !ou are a9are

8/17/2019 1. Core Java

145/177

[email protected]

Java collections can "e considered a 0ind o%read!&ade data structure$ 9e should onl!need to 0no9 ho9 to use the& and ho9 the!9or0<

collection a&e o% topic

Collection

Base inter%ace Collections

Static utilit! class provide various use%ul algorith&

collection

8/17/2019 1. Core Java

146/177

[email protected]

collection

7h! it is called an %ra&e9or08

Read!&ade ata structure in Java

8/17/2019 1. Core Java

147/177

Arra!;ist2 a0a gro9a"le arra!

8/17/2019 1. Core Java

148/177

[email protected]

Arra!;ist o% user de1nedo"ject

8/17/2019 1. Core Java

149/177

o"ject

[email protected]

Co&para"le and Co&parator inter%ace

8/17/2019 1. Core Java

150/177

[email protected]

7e need to teach Java ho9 to sort userde1ne o"ject

Co&para"le and Co&parator inter%acehelp us to tell java ho9 to sort userde1ne o"ject<

I&ple&enting Co&para"le

8/17/2019 1. Core Java

151/177

[email protected]

Co&parator

8/17/2019 1. Core Java

152/177

[email protected]

ont need to change E&plo!ee class

:se%ul stuN

8/17/2019 1. Core Java

153/177

[email protected]

:se%ul e'a&ples

8/17/2019 1. Core Java

154/177

[email protected]

:se%ul e'a&ples

8/17/2019 1. Core Java

155/177

[email protected]

;in0ed;ist 2 AA ou"l! ;in0 list

8/17/2019 1. Core Java

156/177

[email protected]

8/17/2019 1. Core Java

157/177

%unda&ental diN "9 Arra!;ist and;in0ed;ist

8/17/2019 1. Core Java

158/177

[email protected]

Arra!;ists &anage arra!s internall!< KPLK,LK.LK3LK4LK5L

8/17/2019 1. Core Java

159/177

[email protected]

Java i&ple&ents Arra!;ist as arra! internall! (ence good to provide starting si*e

i

8/17/2019 1. Core Java

160/177

[email protected]

(ashMap

8/17/2019 1. Core Java

161/177

[email protected]

e! ++++]Value declaring an hash&ap

(ashMap\Integer$ String] &ap ne9 (ashMap\Integer$String]?@

/opulating values&ap

8/17/2019 1. Core Java

162/177

[email protected]

%or?Integer 0e!2 &ap

8/17/2019 1. Core Java

163/177

[email protected]

;in0ed(ashMap A0a< ou"l! lin0 list

0e! and value are in sa&e order in 9hich !ou have inserted

8/17/2019 1. Core Java

164/177

[email protected]

ont allo9 duplicate ele&ent

:ser de1ne 0e! in (ashMap

8/17/2019 1. Core Java

165/177

[email protected]

I% !ou are using user de1ne 0e! in(ashMap do not %orget to overridehashcode %or that class

7h!8 7e &a! not 1nd that content again

(ashMap vs (ashta"le

8/17/2019 1. Core Java

166/177

[email protected]

(ashta"le is threadsa%e$ slo9 asco&pared to (ashMap

Better to use (ashMap

So&e &ore intresting diNerence (ashta"le give runti&e e'ception i% 0e! is

null 9hile (ashMap dont

Session+.

8/17/2019 1. Core Java

167/177

[email protected]

Java 5 6anguage 2eatures II

;enerics

$nnotations

;enerics

8/17/2019 1. Core Java

168/177

[email protected]

Be%ore Java ,

8/17/2019 1. Core Java

169/177

/ol!&orphic "ehaviour

8/17/2019 1. Core Java

170/177

[email protected]

\8 e'tends ZZZZZZ]

8/17/2019 1. Core Java

171/177

[email protected]

\8 Super ZZZZZ]

8/17/2019 1. Core Java

172/177

[email protected]

Generic class

8/17/2019 1. Core Java

173/177

[email protected]

Generic &ethod

8/17/2019 1. Core Java

174/177

[email protected]

Annotation

8/17/2019 1. Core Java

175/177

[email protected]

^ &agic

Annotations in Java is all a"out adding &eta+data %acilit! tothe Java Ele&ents<

;i0e Classes$ Inter%aces or Enu&s$ Annotations de1ne a

t!pe in Java and the! can "e applied to several JavaEle&ents<

Tools 9hich 9ill read and interpret the Annotations 9illi&ple&ent a lot o% %unctionalities %ro& the &eta+in%or&ation o"tained<

#or e'a&ple$ the! can ensure the consistenc! "et9eenclasses$ can chec0 the validit! o% the para&ters passed "!

the clients at run ti&e and can generate lot o% "ase code

Built+in Annotations in Java

http://www.flipkart.com/head-first-java-8173666024/p/itmczzj44rzzcpcp?pid=9788173666025&affid=suthukrishhttp://www.flipkart.com/head-first-java-8173666024/p/itmczzj44rzzcpcp?pid=9788173666025&affid=suthukrish

8/17/2019 1. Core Java

176/177

[email protected]

There are so&e pre+de1ned annotationsavaila"le in the Java /rogra&&inglanguage< The! are$ Override

eprecated

Suppress7arnings

e&o user de1ne annotation and itsneed

Re%erences2+

8/17/2019 1. Core Java

177/177

Documents

1. Core Java