java unit1

7/25/2019 Java Unit1

1/97

Java An Introduction Programming language developed by Sun Microsystems in 1991.

Originally called Oak by James Gosling

Originally created for consumer electronics ( !" !#$" Mobile

P%one" etc.&

'nternet and eb )as *ust emerging" so Sun turned it into a

language of 'nternet Programming.

Pure Ob*ect oriented language

Java is a )%ole platform" )it% a %uge library" containing lots of

reusable code" and an e+ecution environment t%at provides

services suc% as

security

portability across operating systems

automatic garbage collection.

1


2/97

Need for Java Many di,erent types of controllers )it% di,erent set of #P- are

used in electronic devices.

%e problem )it% # and # is t%at designed to be compiled for a

speci/c target.

0n attempt to solve t%ese problems" Gosling and ot%ers began

)ork on a portable" platformindependent language t%at on avariety of #P-s under di,ering environments.

Second force )as t%e introduction of orld )ide )eb demand a

language t%at could useful in creating portable application.

2


3/97

Java White Paper Buzzwords Simple

Ob*ect Oriented tec%ni2ue for programming t%at focuses on t%edata (3 ob*ects& and on t%e interfaces to t%at ob*ect.

Portable

0rc%itecture 4eutral 5y generating bytecode instructions" make ite+ecutable on many processors" given t%e presence of t%e Javaruntime system.

'nterpreted Java interpreter can e+ecute Java bytecodes directlyon any mac%ine.

4et)orkSavvy Java %as an e+tensive library of routines for coping)it% #P6'P protocols like 7P and 8P.

7ig% Performance J' #ompiler monitor t%e code and optimi:e t%e

code for speed. $obust ;mp%asis on early c%ecking for possible problems" laterdynamic (runtime& c%ecking" and eliminating situations t%at areerrorprone.

Multit%readed

Secure intended to be used in net)orked6distributedenvironments. 3


4/97

Java Milestones

4

=ear Milestones

199> Sun decided to develop a soft)are t%at could be used forconsumer electronics. 0 pro*ect called Green Pro*ectcreated and %ead by James Gosling.

1991;+plored Possibility of using #" )it% some updatesannounced a ne) language named ?Oak@

199A


5/97

Java Applications

Java is used to develop t)o types of application programE

Standalone applications

eb applications (applets&

5


6/97

Java EnvironentJ


7/97

!aple "elloworld application6 Simple 7ello)orld Java application 6

class test

K

public static void main(StringL args&

K

System.out.println(?7ello)orld Java@&N

66 save it as test.*ava

#ompile E *avac test.*ava

;+ecute E *ava test

7ello)orld Java

7


8/97

Process of Buildin# and $unnin# Java Applications

8


9/97

!aple Java E%ecution

9


10/97

Java is &opiled and Interpreted

10


11/97

"ow different fro copiled lan#ua#es'

11


12/97

Platfor Independenc(

12


13/97

Introduction to J)M J!M is t%e interpreter used to convert t%e byte code to mac%ine

code on t%e y and e+ecute it.

5yte code is optimi:ed instruction set )%ic% independent of

mac%ine.JVM Architecture

13


14/97

J)M

Advantages ;nable *ava program run in protected environment

rite once" run any)%ere (one si:e /ts all&

5ro)ser can cac%e t%e do)nloaded code and reuse it later

14


15/97

!pot the errors1. 8i+ t%e errors

#lass


16/97

!pot the errorsA. 'dentify and /+ t%e errors in t%e follo)ing codeE

public class elcome

K

public void main(string argsL&K

System.out.println(elcome to JavaT&N

&

16


17/97

Input Processin#

import *ava.util

public class 'nput


18/97

$eadin# Input-sing #onsole class Java.io

import *ava.util

public class 'nput


19/97

19


20/97

20


21/97

21


22/97

22


23/97

23

* l ti l f J fil


24/97

*eclaration rules for a Java file 0 source code /le can %ave only one public class.

'f t%e source /le contains a public class" t%e /lename must matc%

t%e public class name. 0 /le can %ave only one package statement" but multiple imports.

%e package statement (if any& must be t%e /rst (noncomment&

line in a source /le.

%e import statements (if any& must come after t%e package and

before t%e class declaration.

'f t%ere is no package statement" import statements must be t%e

/rst (noncomment& statements in t%e source /le. package and import statements apply to all classes in t%e /le.

0 /le can %ave more t%an one nonpublic class.

8iles )it% no public classes %ave no naming restrictions.

24

&l A difi


25/97

&lass Access odifiers %ere are t%ree access modi/ersE public" protected" and private.

%ere are four access levelsE public" protected" default" and private.

#lasses can %ave only public or default access. 0 class )it% default access can be seen only by classes )it%in t%e

same package.

0 class )it% public access can be seen by all classes from all

packages.

#lass visibility revolves around )%et%er code in one class can

#reate an instance of anot%er class

;+tend (or subclass&" anot%er class 0ccess met%ods and variables of anot%er class

25

Ja a Tokens


26/97

Java Tokens

Smallest individual units in a program are kno)n as tokens. %e

compiler recogni:es t%em for building up e+pressions and

statements.

0 Java program is a collection of tokens" comments and )%ite spaces.

Java language includes /ve types of tokens. %ey areE

1. 'denti/ers

A. #omments

V. Fey)ords

V. Uiterals

B. OperatorsC. Separators

26

Identifiers


27/97

Identifiers'denti/ers are programmer designed tokens. %ey are used for

naming classes" met%ods" variables" ob*ects" labels" packages and

interfaces in a program. Java identi/ers follo) t%e follo)ing rulesE 'denti/ers must start )it% a letter" a currency c%aracter (W&" or a

connecting c%aracter suc% as t%e underscore ( X &.

'denti/ers cannot start )it% a numberT

0fter t%e /rst c%aracter" identi/ers can contain any combination of

letters" currency c%aracters" connecting c%aracters" or numbers.

'n practice" t%ere is no limit to t%e number of c%aracters an

identi/er can contain. =ou cant use a Java key)ord as an identi/er.

'denti/ers in Java are casesensitiveN foo and 8OO are t)o di,erent

identi/ers.

27

+e#al and Ille#al identifiers


28/97

+e#al and Ille#al identifiers

Legal Identifers

Illegal identifers

28

Nain# &onventions


29/97

Nain# &onventions 4ames of all public met%ods and instance variables start )it% a

leading lo)ercase letter. ;+ampleE average" sum

%en more t%an one )ord are used in a name" t%e second andsubse2uent )ords are marked )it% a leading uppercase letters.

;+ampleE dayemperature" /rst


30/97

&oents#omments %elp programmers to communicate and understand t%e

program. %ey are not programming statements and t%us are ignored

by t%e compiler. 'n Java" comments areEUine #omment Statement preceded by t)o slas%es (66&

5lock #omment Statement enclosed bet)een 6 and 6

Java


31/97

Java ,e(words

31

Java *efault Access Modifier


32/97

Java *efault Access Modifier


33/97

Ei#ht Priitives-

33

;ig%t primitives of *ava areE

8our of t%em are integer typesN t)o are oatingpoint number typesN one ist%e c%aracter type c%arN and one is a 5oolean type for trut% values.

*ata .(pes-


34/97

*ata .(pes-Integer types :

Float types :

34

Character Type


35/97

Character Type

'n order to store c%aracter constants in memory. Java provides ac%aracter data type called c%ar. %e c%ar type assumes a si:e of A bytes but"basically" it can %old only a single c%aracter.

Boolean Type

5oolean type is used )%en )e )ant to test a particular condition duringt%e e+ecution of t%e program. %ere are only t)o values t%at a boolean typecan takeE true or alse. $emember" bot% t%ese )ords %ave been declared askeywords. 5oolean type is denoted by t%e key)ord boolean and uses onlyone it of storage.

T!"# C$%V#&'I$%


36/97

36

36

T!"# C$%V#&'I$%

Type

Conversion

Casting

Operations

Arithmetic

Operations

Ep!icit

Conversion"mp!icit

Conversion

#onvert a data of one type to anot%er before it is used in arit%meticoperations or to store a value of one type into a variable of anot%er type.;+ampleE

byte b1 3 C>Nbyte bA 3 D>N

byte bV 3 b1 bAN;rrorE

?cannot implicitly covert type int to type byte@int bV 3 b1 bAN 66 4o ;rror

'n #Z" type conversions take place in t)o )ays1. 'mplicit conversions

A. ;+plicit conversions

I(plicit Conversions


37/97

37

37

I(plicit Conversions

%e conversion can al)ays be performed )it%out any loss of data. 8ornumeric types" t%is implies t%at t%e destination type can fully represent t%erange of t%e source type. 8or e+ample" a s%ort can be converted implicitly to

an int" because t%e s%ort range is a subset of t%e int range. %erefore"

s%ort b 3 ICNint a 3 bN

Java does t%e conversion automatically. 0n implicit conversion is also kno)n

as automatic type conversion.

%e process of assigning a smaller type to a larger one is kno)n as)idening or promotion.

Some ;+amples of implicit conversion areE

byte +1 3 ICNs%ort +A 3 +1Nint +V 3 +ANlong +B 3 +VNoat +C 3 +BNdecimal +D 3 +BN

Java &onversion hierarch( chart


38/97

38

38

(

short

int

!ong

#!oat

$o%&!e

&yte

char

8 ' &it types

16 ' &it types

32 ' &it types

64 ' &it types

E%plicit &onversions


39/97

39

39

E%plicit &onversions

The process o# assigning a !arger type to a sma!!er one is (no)n as norro)ing* The

norro)ing may res%!t in !oss o# in#ormation*

There are many conversions that cannot &e imp!icit!y ma$e &et)een types* "# )eattempt s%ch conversions+ the compi!er )i!! give an error message*

,or eamp!e+ the #o!!o)ing conversions cannot &e ma$e imp!icit!y-

int to short

int to !ong!ong to int

#!oat to int

$ecima! to any n%meric type

any n%meric type to char

.o)ever+ )e can ep!icit!y carry o%t s%ch conversions %sing the /cast operator* The

process is (no)n as casting an$ is $one as #o!!o)s-

t(pe varia/le0 1 2t(pe3 varia/le4

)aria/les


40/97

)aria/les!ariables is an identi/er t%at denotes t%e storage location used to store a

data value.

!ariable declaration denotes t%ree t%ingsE

ype of t%e value t%e variable going to store.

5ased on t%e place of declaration t%e initial value assigned.

4ame of t%e variable to refer t%e value.

5ased on t%e type t%e si:e of memory allocation is determined.Rules for variable declaration:

Variable name must contain numbers, alphabets, and underscore symbol.

They must not begin with a digit.

Uppercase and lowercase are distinct. This means that the variable Total isnot the same as total or TOTA.

!t should not be a "eyword.

#hite space is not allowed.

Variable names can be of any length. A variable must be declared before it40

)aria/le


41/97

)aria/le%en a variable is assigned a value t%at is too large (in si:e& to bestored" it causes overo). Java does not report )arnings or errors onovero).

;+ample E

int value 3 A1BIB[VDBI 1N 66 value )ill actually be A1BIB[VDB[( causes overo)&

41

Java varia/le t(pes


42/97

Java varia/le t(pes%ree types of variable used in *avaE

Uocal variables ( declared inside function or construct&

'nstance variable ( 4on static variable declared inside t%e class and

accessed using ob*ect& Static variable (declared )it% static modi/er and accessed using

class name&.

;+ampleE

class !ariableN

static int b3A>N

public static void main(StringL ar&

KString c3?7ello@N

!ariable


43/97

Assi#nent !tateents 5 E%pression

43

variable can get t%e value using assignment statement or assignmente+pression.

!alue is assigned using assignment operator

;+ample E

int a 3 1>N

0n e+pression represents a computation involving values" variables"and operators t%at" taking t%em toget%er" evaluates to a value.

;+ampleE

int +3 C (V 6 A& V AN

4oteE Java is strongly typed language i.e." variable on t%e left must becompatible )it% t%e data type of t%e value on t%e rig%t.

&onstants


44/97

&onstants4amed constants or constant represent permanent data t%at neverc%anges its value" once gets initiali:ed.

;+ampleE/nal double pi3 V.1BN

8inal indicate t%at you can assign to t%e variable once.

44

6perators in Java


45/97

6perators in Java

0rit%metic operators

$elational operators

Uogical operators

0ssignment operators

'ncrement and


46/97

p

46

&elational $perators

Logical$perators

Bitwise 6perator


47/97

Bitwise 6perator

47

Assign(ent $perator


48/97

48 48

0ssignment operators are used to assign t%e value of an e+pression to avariable. #Z %as a set of \s%ort%and] assignment operators )%ic% are used int%e form

v op) e+p

v is t%e variablee+p is t%e e+pressionop is t%e binary operator

v op) e+p is e2uivalent to v 3 v op(e+p&N;+E

+ 3 y 1N is e2uivalent to + 3 + (y 1&

Advantages*

. %at appears on t%e left %and side need not be repeated andt%erefore it becomes easier to )rite.

. %e statement is more concise and easier to read.

. %e use of s%ort%and operators results in a more e^cient code.

ncre(en an ecre(en pera or


49/97

49 49

%e operators are and

means 'ncrement Operator means N is e2uivalent to

a L i 3 1>N i 3 i 1N

Conditional $perator't i l k t


50/97

50 50

't is also kno)n as ernary operator

Synta+Ee,p-./ e,p-0* e,p-1

'pecial $perators

Instanceo $perator

%e instanceof is an ob*ect reference operator and returns true if t%eob*ect on t%e left %and side is an instance of t%e class given on t%e rig%t %and side. %is operator allo)s us to determine )%et%er t%e ob*ect belongsto a particular class or not.

;+ampleE

person instanceof student

+ot $perator%e dot operator (.& is used to access t%e instance variables and met%ods

of class ob*ects.

;+ampleE

person1.age 66$eference to t%e variable age

person1.salary( & 66$eference to t%e met%od salary( &

*ecision Ma7in# !tateents


51/97

#)o types of


52/97

2 ( 3#onsists of a 5oolean condition follo)ed by one or statement.

$ynta%:

if(5ooleanXe+pression&

K

66Statements )ill e+ecute if t%e 5oolean e+pression is true

;+ampleE Problem statement

#alculate t%e area of t%e circle in case of radius is positive integer

class 0reaK


K

Scanner s3ne) Scanner(System.in&N

int rad3s.ne+t'nt(&N

if(rad>&K

System.out.println( ? t%e area is ? (V.1B rad rad&&N

52

.wo wa( if stateent


53/97

(%en t%ere are multiple conditions need to be evaluated t%en )e can use ifelse construct. 'f t%e condition is true one set of statement e+ecutesot%er)ise alternate set get e+ecuted.

Synta+E

if (booleane+pression& K

statement(s&fort%etruecaseN

else K

statement(s&fort%efalsecaseN

53

Nested if structure


54/97

4ested if structure come into play )%en t%ere are too many alternateconditions to be evaluated.

Synta+Eif (booleane+pression&

K

if (booleane+pression&

K

statement(s&fort%etruecaseN

else

K

statement(s&fort%efalsecaseN

54

4 ti i l t t t


55/97

4esting i2elsestatementi(5ooleane+pression&K

rueblock statement(S&

i(5ooleane+pression&Krueblock Statement(s&

elseK

8alseblock Statement(s&

elseK

8alseblock statement(s&

else i Ladder*


56/97

i(conditionX1&StatementX1N

else i(conditionXA&

StatementXANelse i(conditionXV&

StatementXVN..

. else i(conditionXn&

StatementXnNelse


57/97

1.8orgetting 4ecessary 5races

A. rong Semicolon at t%e if Uine

57

&oon errors in !election stateent


58/97

V. $edundant esting of 5oolean !alues

B.


59/97

1. #ode to c%eck )%et%er t%e number entered by user is even or odd number.

A. 5ody Mass 'nde+ (5M'& is a measure of %ealt% on )eig%t. 't can be calculated bytaking your )eig%t in kilograms and dividing by t%e s2uare of your %eig%t inmeters. %e interpretation of 5M' for people 1D years or older is as follo)sE

V. #omputing ta+es E %e -nited States federal personal income ta+ is calculatedbased on /ling status and ta+able income. %ere are four /ling statusesE single/lers" married /ling *ointly" married /ling separately" and %ead of %ouse%old. %eta+ rates vary every year. able V.A s%o)s t%e rates for A>>9. 'f you are" say" single)it% a ta+able income of W1>">>>" t%e /rst W["VC> is ta+ed at 1>` and t%e ot%erW1"DC> is ta+ed at 1C`. So" your ta+ is W1">[A.C

59

!cenarios


60/97

Uottery E Suppose you )ant to develop a program to play lottery. %eprogram randomly generates a lottery of a t)odigit number" prompts t%euser to enter a t)odigit number" and determines )%et%er t%e user )insaccording to t%e follo)ing ruleE

1. 'f t%e user input matc%es t%e lottery in e+act order" t%e a)ard is W1>">>>.

A. 'f all t%e digits in t%e user input matc% all t%e digits in t%e lottery" t%ea)ard is WV">>>.

V. 'f one digit in t%e user input matc%es a digit in t%e lottery" t%e a)ard isW1">>>.

60

!witch case


61/97

0 s)itc% statement allo)s a variable to be tested for e2uality against a list of

values. ;ac% value is called a case" and t%e variable being s)itc%ed on is

c%ecked for eac% case. 'f statement makes a problem di^cult" )%en too

many c%oices are t%ere to evaluate in suc% circumstances s)itc% is t%e

alternative.

Synta+E

s)itc%(e+pression&

K

case value E

66Statements

breakN66optional

case value E

66Statements

breakN66optional

defaultE66Optional

66Statements

61

T3# '4ITC3 'TAT#M#%T


62/97

switch(e+pression&K

casevalueX1E

blockX1NreakN

casevalueXAEblockXANreakN

casevalueXVE

blockXVNreakN

deaultE

defaultXblockreakN

StatementX+N

$ules for switch


63/97

%e s)itc%e+pression must yield a value of c%ar" byte" s%ort" or int type

and must al)ays be enclosed in parent%eses.

%e value1" and value4 must %ave t%e same data type as t%e value of t%e

s)itc%e+pression. 4ote t%at value1" and value4 are constant e+pressions"

meaning t%at t%ey cannot contain variables" suc% as 1 +.

%en t%e value in a case statement matc%es t%e value of t%e s)itc%

e+pression" t%e statements starting from t%is case are e+ecuted until eit%er

a break statement or t%e end of t%e s)itc% statement is reac%ed.

%e key)ord break is optional. %e break statement immediately ends t%e

s)itc% statement.

%e default case" )%ic% is optional" can be used to perform actions )%ennone of t%e speci/ed cases matc%es t%e s)itc%e+pression.

%e case statements are c%ecked in se2uential order" but t%e order of t%e

cases (including t%e default case& does not matter. 7o)ever" it is good

programming style to follo) t%e logical se2uence of t%e cases and place63

!cenario


64/97

Scissorrockpaper gameE %e program randomly generates a number >" 1" orA representing scissor" rock" and paper. %e program prompts t%e user toenter a number >" 1" or A and displays a message indicating )%et%er t%e useror t%e computer )ins" loses" or dra)s.

'n a ?main@ met%od" generate a random integer bet)een 1 and 1V torepresent t%e possible values in a suit of playing cards.

-se a ?s)itc%@ statement t%at applies cases to your random integer.

'f t%e random number is 1" print out ?0ce@ to t%e console.

'f t%e random number is 11" print out ?Jack@ to t%e console.

'f t%e random number is 1A" print out ?ueen@ to t%e console.

'f t%e random number is 1V" print out ?Fing@ to t%e console.%e default case s%ould simply print t%e random integer to t%e console.

64

&onditional E%pression


65/97

%en )e )ant to assign a value to a variable based on certain condition tobe evaluated" t%e )e can use conditional e+pression.

'ynta,*

Y3 booleane+pression R e+pression1 E e+pressionAN#,a(ple *

o /nd t%e biggest of t)o numbersE

class 5ig

K


K

int a3'nteger.parse'nt(arL>&N

int b3'nteger.parse'nt(arL1&N

if(ab&

System.out.println ( ? a is big ?&N

else

System.out.println ( ? b is big ?&N

$eplaced byE

65

66replaced entire ifstatement

int res 3 ( a b & R a E b N

E%ercises


66/97

.5 &ewrite the ollowing state(ent using a conditional e,pression*

if (temperature 9>&

pay 3 pay 1.CN

elsepay 3 pay 1.1N

05 4rite a progra( that pro(pts the user to enter the (onth andyear and displays the nu(er o days in the (onth5 6or e,a(ple7 ithe user entered (onth 0 and year 08887 the progra( should displaythat 6eruary 0888 has 09 days5 I the user entered (onth 1 andyear 088:7 the progra( should display that March 088: has 1. days5

15 4rite a progra( that pro(pts the user to enter an integer andchecks whether the nu(er is divisile y oth : and ;7 or neither o

the(7 or se a switch state(ent to rewrite the ollowing i state(ent anddraw the ?ow chart or the switch state(ent*


67/97

if (a 33 1&

+ 3 CN

else if (a 33 A&

+ 3 1>Nelse if (a 33 V&

+ 3 1DN

else if (a 33 B&

+ 3 VBN

;5 4rite a switch state(ent that assigns a 'tring variale day%a(ewith 'unday7 Monday7 Tuesday7 4ednesday7 Thursday7 6riday7'aturday7 i day is 87 .7 07 17 =7:7 ;7 accordingly5

@5 &ewrite the ollowing i state(ent using the conditional operator*if (count ` 1> 33 >&

System.out.print(count QHnQ&N

else

System.out.print(count Q Q&N

67

+oops


68/97

Uoop is control structure t%at e+ecutes t%e se2uence statement multiple

times based on condition. Java supports t%ree di,erent set of iteration

statements suc% asE

%ile loop


69/97

5ased on conditional e+pression inside t%e loop" t%e set of statements gete+ecuted multiple times

'ynta,*

initiali:ationN

)%ile(testXcondition&

K

5ody of t%e Uoop

#,a(ple*

#ounting of numbers 1 to 1>>

&&code

int sum, count'()

while*count+((-

sum/'count)

count//)

0

$.O.1*count-)69

+o4hile loopd %il l i i ti f t% %il l % d %il l t t%


70/97

do)%ile loop is a variation of t%e )%ile loop. %e do)%ile loop e+ecutes t%eloop body /rst" t%en c%ecks t%e loop continuationcondition to determine)%et%er to continue or terminate t%e loop.

Syntax :

do K

66 Uoop bodyN

Statement(s&N

)%ile (loopcontinuationcondition&N

Tip: Use the do-hile loop if you ha!e state"ents inside the loop

that "ust #e executed at least once$i"port %a!a$util$Scanner&

pu#lic class TestDo'hile (

pu#lic static !oid "ain)String*+ args, (

int data su" . /&

Scanner input . ne Scanner)Syste"$in,&Syste"$out$print)0Enter an int !alue )the progra" exits if the inputis /,: 0,&

data . input$nextInt),&

su" 1. data&

Syste"$out$println)0The su" is 0 1 su",&70

6or Loop0 for loop is a repetition control structure t%at allo s ou to e^cientl rite a


71/97

0 for loop is a repetition control structure t%at allo)s you to e^ciently )rite aloop t%at needs to e+ecute a speci/c number of times.

'ynta,*

for (initiali:ationNtestXconditionNincrement&

K

5ody of t%e Uoop

#,a(ple*

public class est

K

public static void main(String argsL&

K

for(int + 31>N + A>N + 3 +1&

K

System.out.print(Qvalue of + E Q + &N

System.out.print(QHnQ&N

71

#nhanced or loop'ynta,*


72/97

'ynta,*

for(declaration E e+pression&

K 66Statements

+eclaration*

%e ne)ly declared block variable" )%ic% is of a type compatible )it% t%eelements of t%e array you are accessing. %e variable )ill be available )it%int%e for block and its value )ould be t%e same as t%e current array element.

#,pression*

%is evaluates to t%e array you need to loop t%roug%. %e e+pression can be

an array variable or met%od call t%at returns an array.#,a(ple*

public class est

K public static void main(String argsL&

K

for( String s E args&K

System.out.println(s&N

72

Additional 8eatures of the for +oop&ase 0-

p 1 09

&ase -for 2 1 0:::9 F:9 1 039

&


73/97

73 73

p 9

for 2n 1 :9 n;0n1:9n;01?:9n;19 n1n=0>1@03

@@@@@@@@@@

@@@@@@@@@@

&ase C-

su 1 :9

for 2 i 10> i;4: 55 su ;0::9 i==3

@@@@@@@@@@@

@@@@@@@@@@@

&ase D-

for 2% 1 2=n349 %F:9% 1 %43

&ase ?-

@@@@@@@@@

@@@@@@@@@ 1 ?9

for 29 G1 0::93

!(steHoutHprintln239

1 = ?9

@@@@@@@@@@@@@@@@

&ase


74/97

74

continueNgotoN

pulic class BreakContinue4ithLael

pulic static void (ain'tring argsDEF

intDE nu(ers) new intDE.887.G70.718H$>T#&*orint i ) 8 inu(ers5length iKKF

ii 0 )) 8F

'yste(5out5println$dd nu(er* K i K 7 continue ro( $>T#&laelF

continue $>T#& H I%%#&*

orint < ) 8


75/97

3$ 'rite a code to re!erse the nu"#er using hile loop$

4$ 5reatest Co""on di!isor: 6et the to input integers #e n3 and

n4$ 7ou 8no that nu"#er 3 is a co""on di!isor #ut it "ay not #e

the greatest co""on di!isor$ So you can chec8 hether 8 )for8 4 9

and so on, is a co""on di!isor for n3 and n4 until 8 is greater

than n3 or n4$ Store the co""on di!isor in a !aria#le na"ed gcd$

Initially gcd is 3$ 'hene!er a ne co""on di!isor is found it

#eco"es the ne gcd$

9$ ;redicating the Future Tuition: Suppose that the tuition for a

uni!ersity is e!ery year$

In ho "any years ill the tuition #e dou#led?

75

$eview Kuestions@ l th f ll i d I t B 3// l t l f l


76/97

@nalyAe the folloing code$ Is count B 3// alays true alays falseor so"eti"es true or so"eti"es false at ;oint @ ;oint and ;ointC?

int count ' ()

while *count + ((-

&& 1oint A

$ystem.out.println*2#elcome to 3ava45n2-)

count//)

&& 1oint 6

0 && 1oint 7

o "any ti"es is the folloing loop #ody repeated? 'hat is theprintout of the loop?

76

'hat are the dierences #eteen a hile loop and a do-hile loop?Con!ert the folloing hile loop into a do-hile loop$


77/97

int sum 3 >N

int number 3 input.ne+t'nt(&N

)%ile (number T3 >& K

sum 3 numberNnumber 3 input.ne+t'nt(&N

Do the folloing to loops result in the sa"e !alue in su"?

Can you alays con!ert a hile loop into a for loop? Con!ert the

folloing hile loop into a for loop5int i 3 1" sum 3 >N

)%ile (sum 1>>>>& K

sum 3 sum iN

iN

77


78/97

Suppose the input is 4 9 /$ 'hat is the output of the folloingcode?

import *ava.util.ScannerNpublic class est K

public static void main(StringL args& K

Scanner input 3 ne) Scanner(System.in&N

int number" ma+N

number 3 input.ne+t'nt(&Nma+ 3 numberN

)%ile (number T3 >& K

number 3 input.ne+t'nt(&N

if (number ma+&

ma+ 3 numberN

System.out.println(Qma+ is Q ma+&N

System.out.println(Qnumber Q number&N

78

'hat is the 8eyord #rea8 for? 'hat is the 8eyord continue for?'ill the folloing progra" ter"inate? If so gi!e the output$


79/97

The for loop on the left is con!erted into the hile loop on the right$'hat is

rong? Correct it$

79

@fter the #rea8 state"ent is executed in the folloing loop hichstate"ent is executed? Sho the output$


80/97

for (int i 3 1N i BN i& K

for (int * 3 1N * BN *& K

if (i * A&

breakNSystem.out.println(i *&N

System.out.println(i&N

@fter the continue state"ent is executed in the folloing loophich state"ent is executed? Sho the output$

for (int i 3 1N i BN i& K

for (int * 3 1N * BN *& K

if (i * A&continueN

System.out.println(i *&N

System.out.println(i&N

80

Identify and Gx the errors in the folloing code:public class est K


81/97

public void main(StringL args&

K

for (int i 3 >N i 1>N i&N

sum 3 iNif (i *&N

System.out.println(i&

else

System.out.println(*&N

)%ile (* 1>&NK

*N

N

K

*N )%ile (* 1>&

81

'hat is rong ith the folloing code?


82/97

82

'rite a progra" that displays all the nu"#ers fro" 3// to 3///ten per line that are di!isi#le #y and H$

Use a hile loop to Gnd the s"allest integer n such that n4 isgreater than 34///$

'rite a progra" that reads an integer and displays all its s"allest

factors in increasing order$ For exa"ple if the input integer is 34/the output should #e as follos: 4 4 4 9 $

rite a program t%at displays all t%e numbers from 1>> to 1>>>


83/97

rite a program t%at displays all t%e numbers from 1>> to 1>>>"ten per line" t%at are divisible by C and D.

-se a )%ile loop to /nd t%e smallest integer n suc% t%at nA isgreater t%an 1A">>>.

83

Array 0n array is a data structure )%ic% de/nes an ordered collection of a


84/97

0n array is a data structure )%ic% de/nes an ordered collection of a/+ed number of %omogeneous data elements

%e si:e of an array is /+ed and cannot increase to accommodatemore elements

'n Java" array are ob*ects and can be of primitive data types orreference types

0ll elements in t%e array must be of t%e same data type

Creating an Array1.


85/97

arrayname 3 ne) type Lsi:eN

;+amplesE

number 3 ne) int LCNaverage 3 ne) oat L1>N

15 +eclaration and Creation in one step

Synta+E

type L arrayname 3 ne) type Lsi:eN;+amplesE

int L number 3 ne) int LCN

=5 InitialiNation o Arrays

Synta+E type L arrayname 3 Klist of valuesN

;+ampleE

int L number 3 KVA"BC"VB"CD"VBN

int L number 3 ne) int LV K1>"A>"V>N

85

$ne +i(ensional Array* 0 list of liketyped ele(ents. 8irst create an array variable of t%e desired type


86/97

8irst create an array variable of t%e desired type. new is a special operator t%at allocates memory. 0ssigning values are based on t%e array variable inde+ ranges from 8 to

n.N

o display t%e values in output is also based on inde+.

class 0rraysK

public static void main(String argsL&K

int mont%XdaysLNmont%Xdays 3 ne) intL1ANmont%XdaysL> 3 V1N mont%XdaysLD 3 V1Nmont%XdaysL1 3 A[N mont%XdaysLI 3 V1Nmont%XdaysLA 3 V1N mont%XdaysL[ 3 V>Nmont%XdaysLV 3 V>N mont%XdaysL9 3 V1Nmont%XdaysLB 3 V1N mont%XdaysL1> 3 V>Nmont%XdaysLC 3 V>N mont%XdaysL11 3 V1NSystem.out.println(?0pril %as ? mont%XdaysLV ?days@&N

$O"* April has 18 days

class 4umberSortingK


87/97

public static void main(String argsL&K

int numberL 3 KCC"B>"[>"DC"I1N

int n 3 number.lengt%NSystem.out.println(QGiven UistQ&Nfor(int i 3 >NinNi&K

System.out.println(Q Q numberLi&N

System.out.print(QHnQ&Nfor(int i 3 >Ni nN i&K

for(* 3 1N* nN *&K

if (numberLi number L*&

Kint temp 3 numberLiNnumberLi 3 numbdfL*NnumberL* 3 tempN

System.out.println(QSorted listEQ&N


88/97

for(int i 3 >Ni nNi&K

System.out.println(Q Q numberLi&N

System.out.println(Q Q&N

The PoreachQ loop* 0 po)erful looping construct t%at allo)s repeating for eac% element in an

array )it%out %aving to con/rm )it% inde+ values.

'ynta,* orvariale * collectionFstate(ent

#,* int aDE ) .87087187=87:8Hor int * aF

'yste(5out5printlnF

J til A


89/97

Java5util5Arrays*

%e


90/97

;+Eint L a 3 K1"A"VNint L bN

b 3 aN

Two +i(ensional Array

">">"K1"1"1N

class MultiableK

/nal static int $OS 3 CN


91/97

/nal static int $OS CN/nal static int #OU-M4S 3 CN

public static void main(String argsL&

Kint productLL 3 ne) intL$OSL#OU-M4SNint ro)"columnN

System.out.println(QMultiplication ableQ&NSystem.out.println(Q Q&N

int i"*Nfor(i31Ni$OSNi&K

for(*31N*#OU-M4SN*&K

productLiL* 3 i *NSystem.out.print(Q Q productLiL*&N

System.out.println(Q Q&N

Variale R 'iNe Arrays

!ariable Si:e array is called Array o Array or %ested Array or


92/97

92 92

!ariable Si:e array is called Array o Arrayor %ested ArrayorJagged Array

;+E

int L L + 3 ne) int LV L N 66%ree ro)s array

+ L> 3 ne) int LA 668irst $o)s %as t)o elements+ L1 3 ne) int LB 66Second $o)s %as four elements+ LA 3 ne) int LV 66%ird $o)s %as t%ree elements

0

1

2

0 1

1 3

2 2

public class My0rraycAK

public static void main(String argsL &


93/97

93

public static void main(String argsL &K

Scanner s3ne) Scanner(System.in&NintLL *ag3ne) intLVLN

*agL>3ne) intLBN*agL13ne) intLVN*agLA3ne) intLCNSystem.out.println(Q;nter t%e array elementsQ&Nfor(int i3>Ni*ag.lengt%Ni&K

for(int *3>N**agLi.lengt%N*&*agLiL*3s.ne+t'nt(&N

for(int i3>Ni*ag.lengt%Ni&K

for(int *3>N**agLi.lengt%N*&K

System.out.print(*agLiL* QHt Q&NSystem.out.println(&N

!ariable lengt% argumentsJava allo)s us to pass a variable number of arguments of t%e same


94/97

J p gtype to a met%od. %e parameter in t%e met%od is declared asfollo)sE

type4ame... parameter4ames

$ulesE

0 function s%ould contain only one variable lengt% parameter

%e variable lengt% parameter must be last in t%e list

Preceded by any number usual parameters.

94

class v0rgK


95/97

public static void printMa+(int... numbers &

K

for (int i 3 >N i numbers.lengt%N i&

K

System.out.println( numbersLi &N

public static void main(StringL ar&K

printMa+(1"A"V"B"C&N

printMa+(1"A"B&N

95

Pat% #lassPat% P07 and #U0SSP07 are operating system level environment


96/97

variables.

P07 is used to de/ne )%ere t%e system can /nd t%e e+ecutables(.e+e& /les ;+ample pat%3 cEHprogram /lesH*avaH*dk.I.>X>CHbin

#U0SSP07 is used to specify t%e location of .class /les

96

J0$Steps to create *ar 8ileE


97/97

create a *ava code save t%e /le

compile t%e *ava /les to create .class /les

create a (aniestmanifest is t%e description contains t%e main class %eader

;+ampleE Main#lassE classname

save it in .mft e+tension

create

java unit1

Documents