1. klabscorejava draft need cover page

8/9/2019 1. KLabsCoreJava Draft Need Cover Page

1/16

1Core Java Siva Kameswara Rao Munipalle

Audience (Who is this book for.. ? )

This book is intended for all those who have a basic idea on Java ( You need not be an expert!! " This will make #ou

perfect in $ava

www.theknowledgelabs.wordpress.com


2/16


Table of Contents

HISTORY OF JAA..................................................................................................................... 3

HO! JAA !OR"S#.................................................................................................................. 3

JAA $R%&R%'(ISIT%S............................................................................................................... 3

S%TTI)* ($ JAA %)IRO)+%)T................................................................................................. 4

I,%-S.....................................................................................................................................5

OO$S O/J%0T ORI%)T%, $RO*RA++I)* I) JAA..........................................................................5

TH% R%F%R%)0% A), O/J%0T 0R%ATIO) I) JAA............................................................................ 5

0O)STR(0TORS......................................................................................................................5

THIS A), S($%R..................................................................................................................... 5

+%+ORY +A)A*%+%)T............................................................................................................ 5

0O)TRO STAT%+%)TS.............................................................................................................5

A00%SS +O,IFI%RS..................................................................................................................5

)O)&A00%SS +O,IFI%RS........................................................................................................... 6

$RI+ITI% S !RA$$%R 0ASS%S................................................................................................ 6

TY$% 0ASTI)* A), TH% 0O)S%'(%)0%S..................................................................................... 6

O%RRI,I)*........................................................................................................................... 6

O%ROA,I)*........................................................................................................................ 6

I++(TA/% 0ASS................................................................................................................... 7

I++(TA/% 0ASS%S AR% THOS% 0ASS%S3 !HOS% O/J%0T 0A))OT /% +O,IFI%, O)0% 0R%AT%,3 IT

+%A)S A)Y +O,IFI0ATIO) O) I++(TA/% O/J%0T !I R%S(T I) A)OTH%R I++(TA/% O/J%0T...........7

,IFF%R%)0% /%T!%%) STRI)* A), STRI)*/(FF%R....................................................................... 7

THR%A,S............................................................................................................................... 7

0O%0TIO)S FRA+%!OR"...................................................................................................... 7

%40%$TIO)S........................................................................................................................... 7

%&&'()*+..............................................................................................................................8



3/16


H6stor7 o8 Ja9a

Java has become so popular with the Java b#te,code- which is platform independent

*n .//.- a 0roup of Sun Micros#stems en0ineers led b# James 1oslin0 decided to develop a lan0ua0e for consumer devices (cable

boxes- etc" The# wanted the lan0ua0e to be small and use e2cient code since these devices do not have powerful C&3s The#

also wanted the lan0ua0e to be hardware independent since di4erent manufacturers would use di4erent C&3s The pro$ect was

code,named

1reen

These conditions led them to decide to compile the code to an intermediate machine,like code for an ima0inar# C&3 called a

virtual machine (%ctuall#- there is a real C&3 that implements this virtual C&3 now" This intermediate code (called b#te code" is

completel# hardware independent &ro0rams are run b# an interpreter that converts the b#te code to the appropriate native

machine code

Thus- once the interpreter has been ported to a computer- it can run an# b#te,coded pro0ram

Sun uses 3*+ for their computers- so the developers based their new lan0ua0e

on C55 The# picked C55 and not C because the# wanted the lan0ua0e to be ob$ect,oriented The ori0inal name of the lan0ua0e

was 6ak 7owever- the# soon discovered that there was alread# a pro0rammin0 lan0ua0e called 6ak- so the# chan0ed the name

to Java

The 1reen pro$ect had a lot of trouble 0ettin0 others interested in Java for smart devices *t was not until the# decided to shift

0ears and market Java as a lan0ua0e for web applications that interest in Java took o4 Man# of the advanta0es that Java has for

smart devices are even bi00er advanta0es on the web

How Ja9a works#

Java ,,,,,, Java compiler ,,,,,, class 8les 9 You need J)K to do this:

class 8le 9b#te,code: is passed across the networks as this is a binar# 8le

class ,,,,,, J;M ,,, native code 9 You can do this with a JR' J)K internall# contains JR':

Sometimes all the class 8les are packed into a sin0le 8le and is called $ar 9Java %chieve:



4/16

:Core Java Siva Kameswara Rao Munipalle

packagecom.KLabs.CoreJava;

publicclassFirstProgram {

publicstaticvoidmain(String[] args) {

System.out.println(!ey.." !ai..#elcome to Java);

$

$

Ja9a pre&re; %dvanced tab

Click on 'nvironment ;ariables- under S#stem ;ariables- 8nd &%T7- and click on it

*n the 'dit windows- modif# &%T7b# addin0 the location of the class to the value for &%T7 *f #ou do not have the

item &%T7- #ou ma# select to add a new variable and add &%T7as the name and the location of the class as the

value


O=$

!ey.." !ai..#elcome to Java


5/16

>Core Java Siva Kameswara Rao Munipalle

Reopen Command prompt window- and run #our $ava code

Windo"s '# Start ,> Control &anel ,> S#stem ,> %dvanced

Click on 'nvironment ;ariables- under S#stem ;ariables- 8nd &%T7- and click on it

*n the 'dit windows- modif# &%T7b# addin0 the location of the class to the value for &%T7 *f #ou do not have the

item&%T7

- #ou ma# select to add a new variable and add&%T7

as the name and the location of the class as the

value

Close the window

Reopen Command prompt window- and run #our $ava code

Checkin the n*iron+ent

*f #our environment variables are set correctl#- #ou should see #our settin0s

6r- #ou can $ust t#pe in

$avac

$ava

*f #our &%T7 and C=%SS&%T7 is correct- windows should reco0ni?e those commandsYou do 6T need to restart #our computer when installin0 Java

I,%-s

OO$s Ob?ect Or6ented $rogramm6ng 6n Ja9a

'ncapsulation

&ol#morphism

%bstraction

*nheritance

'ncapsulation

'ncapsulation is the abilit# to packa0e data- related behavior in an ob$ect bundle and control@restrict access to them (both data

and function" from other ob$ects This is done with the help of access, modi8ers



6/16

@Core Java Siva Kameswara Rao Munipalle

&ol#morphism

This enables to have sin0le method names used di4erentl# , overridin0- overloadin0

%bstraction

*nheritance

The Re8erence and Ob?ect 0reat6on 6n Ja9a

The 6b$ect is created usin0 thenew

ke#word

new Classame("A

Can we create ob$ect for abstract Class or interface B

0onstr


7/16

Core Java Siva Kameswara Rao Munipalle

0ontrol Statements

Access +od6Bers

public

private

protected

default

)on&Access +od6Bers

static

8nal

s#nchroni?ed

abstract

interface

Static



8/16

CCore Java Siva Kameswara Rao Munipalle

Static ;ariable

Static initiali?er static block with no function names

Thu+b ,uleStatic initiali?er block is executed onl# once when the class is loaded

*nterfaceD

;ariables can be declared in an interface

;ariables are implicitl# public- static- and 8nal

%n interface can extend another interface

% Class implements interface to de8ne the abstract methods

Can an -nterface be nal?

)o we can-t declare an 6nter8ace to be Bnal.

Can "e dene /ri*ate and /rotected +odiers for *ariables in interfaces?

)o3 9ar6ables are p


9/16

NCore Java Siva Kameswara Rao Munipalle

Abstract Class

*tEs a class which cannot be instantiated withnew("operator

You need to extend it and provide a concrete class

%bstract class is commonl# used to de8ne base class for a t#pe hierarch# with default implementation- which is

applicable to all child classes

Can abstract class ha*e Constructor?

$r6m6t69e s !rapper 0lasses

T7pe 0ast6ng and the conse;


10/16


0ollect6ons Framework

1roup of ;alues 9 ollections :

%llow all values F *nsertion order , %rra#=ist

o duplicates ,

Guick F Random , 7ashSet

Guick F *nsertion 6rder , =inked7ashSet

Guick F Sorted , TreeSet

Ke#, value pairs 9Map :

Random H 7ashMap

*nsertion 6rder , =inked7ashMap

Sorted , TreeMap

%cept6ons

Checked

P These are exceptions that are checked durin0 the compile time

P The compiler forces to handle these exceptions usin0 either tr#catch(" or usin0 throws

3nchecked

These exceptions occur durin0 the runtime&ro0rammer ma# not expect such errors

3ser, )e8ned



11/16


%ppendix

Collectionssort

Collectionss#nchroni?edMap

collectionss#nchroni?ed=ist

Ihat is the di4erence between J)K and JR'

J)K is a complete

&ro0ram ilesJava$dk.LNO.

&ro0ram ilesJava$dk.LNO.bin

&ro0ram ilesJava$dk.LNO.$rebin

Ihere does the 8rst execution startB

)i4erence between 7eap and Stack memor#B

*s Java pass b# value or pass b# referenceB

Java =ibrar# @Java %&*B

*s,% ;s 7as,% relation B

Ihat is the di4erence between 7ashTable and 7ashMapB

)oes importin0 comK=absP import all the sub packa0es like comK=absCoreJavaB

Ihat is the di4erence between de8nin0 and declarin0 variableB

)e8nin0D Strin0 sA

)eclarin0D Strin0 s


12/16


packagecom.KLabs.CoreJava

publicclassFirstProgram {

privatestaticvoidmain(String[] args) {

System.out.println(!ey.." % am in private main.."");

$

$

)o comp6lat6on %rrors

R


13/16


7ashMap Key-ale Pairs

=inked7ashMap Key-ale Pairs

TreeMap Key-ale Pairs

Tree , Sorted 9%scendin0 order:

Set , o )uplicates

7ash ,

Map , ke# value pairs

*terator

The $avautil classes are listed here

%bstractCollection (Java " 'vent 6b$ect &ropert#Resourceundle

%bstract=ist (Java " 1re0orianCalendar Random

%bstractMap (Java " 7ashMap (Java " Resourceundle

%bstractSeQuential=ist (Java " 7ashSet (Java " SimpleTimeone

%bstractSet (Java " 7ashtable Stack

%rra#=ist (Java " *dentit#7ashMap (Java " Strin0Tokeni?er

%rra#s (Java " =inked7ashMap (Java " Timer (Java - v.U"

itSet =inked7ashSet (Java " TimerTask (Java - v.U"

Calendar =inked=ist (Java " Timeone

Collections (Java " =istResourceundle TreeMap (Java "

Currenc# (Java - v.V" =ocale TreeSet (Java "

)ate 6bservable ;ector

)ictionar# &roperties Ieak7ashMap (Java "

'vent =istener&rox# (Java - v.V" &ropert#&ermission (Java "

$avautil de8nes the followin0 interfaces otice that most were added b# Java

Collection (Java " =ist (Java " Random%ccess (Java - v.V"

Comparator (Java " =ist*terator (Java " Set (Java "

'numeration Map (Java " SortedMap (Java "



14/16

1:Core Java Siva Kameswara Rao Munipalle

'vent=istener Map'ntr# (Java " SortedSet (Java "

*terator (Java " 6bserver

*er ,idin Conce/ts


publicclass/ {

publicvoidmet0o'&ne()

{

System.out.println(Sper Class);

$

$


publicclass1 extends/{

publicvoidmet0o'&ne()

{

System.out.println(Sb Class);

$

$


A & /ase 0lass S


15/16

1>Core Java Siva Kameswara Rao Munipalle

Super lass Sub lass %llows overridin0

&ublic &ublic Yes

&rivate

protected

default&rivate &ublic

&rivate

protected

default

protected &ublic

&rivate

protected

default

default &ublic

&rivate

protected

default

Thu+b ,uleD ase class methods cannot be private or protected The# can be public @default

The overridin0 method cannot have a more restrictive access modi8er than the method bein0 overridden ('xD You

canWt override a method marked public and make it protected"

You cannot override a method marked 8nal

You cannot override a method marked static

ase class method is Static B

ase class throws exceptions not sub class doesnWt throwB SubClass throws exception but aseClass doesnWt throw exceptionB

ase class method has parameter , double and sub class ,intB

ase class ,(lon0 - int" and sub class (int - lon0" B


publicclass/ {

privatevoidmet0o'&ne()

{

System.out.println(Sper Class);

$

$


publicclass1 extends/{



16/16

1@Core Java Siva Kameswara Rao Munipalle

pblic voidmet0o'&ne()

{

System.out.println(Sb Class);

$

$

1. klabscorejava draft need cover page

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