java streams n filing

8/9/2019 JAVA Streams n Filing

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JAVA Software DevelopmentParadigm

Advance OO Programming

BSCS Semester 6MCS 3Course Instructor: Ms. Iram


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Streams• A stream is deri,ed from se/uential in ut or out ut

de,ices.• An in ut stream roduces a stream of c!aracters0• An out ut stream recei,es a stream of c!aracters) $one

at a time.%• Streams a l( not +ust to files) 'ut also to I de,ices)Internet streams) and so on.

• A file can 'e treated as an in ut or out ut stream.•

In realit( file streams are 'uffered for efficienc(: it is notractical to read or rite one c!aracter at a time from

or to mass storage.• It is common to treat te"t files as streams.


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+a,a.ioBufferedIn utStreamBuffered ut utStreamBuffered eaderBuffered riterB(teArra(In utStreamB(teArra( ut utStreamC!arArra( eaderC!arArra( riter

ataIn utStreamata ut utStream

FileFile escri torFileIn utStreamFile ut utStreamFile5ermissionFile eaderFile riterFilterIn utStreamFilter ut utStreamFilter eaderFilter riter

In utStreamIn utStream eader

ine7um'erIn utStreamine7um'er eader'+ectIn utStream'+ectIn utStream.8etField'+ect ut utStream'+ect ut utStream.5utField'+ectStreamClass'+ectStreamFieldut utStreamut utStream riter

5i edIn utStream5i ed ut utStream5i ed eader5i ed riter5rintStream5rint riter5us!'ac9In utStream5us!'ac9 eader

andomAccessFileeader

Se/uenceIn utStreamSeriali a'le5ermissionStream o9eni erStringBufferIn utStreamString eaderString riter

riter

;o do I

read an int from a file


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+a,a.io #cont>d&• ?ses four !ierarc!ies of classes rooted at

eader ) riter ) In utStream ) ut utStream .• In utStream @ut utStream !ierarc!ies deal

it! '(tes. eader @riter !ierarc!ies dealit! c!ar s.

• ;as a s ecial stand-alone classandomAccessFile .

• !e Scanner class !as 'een added to +a,a.util to facilitate reading num'ers and

ords.


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+a,a.io.File• !e File class re resents a file #or folder& in

t!e file director( s(stem.

• Met!ods:String get7ame#&String getA'solute5at!#&long lengt!#&'oolean is irector(#&File listFiles#&

String at!name D..@ ata@ ords.t"t$0File file ne File# at!name&0


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eading Files using scanner

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File file ne File#Dm(file.t"tD&0

Scanner in ut null0 tr( in ut ne Scanner#file&0 !ile#in ut.!as7e"t ine#&&

S(stem.out. rintln#in ut.ne"t ine#&&0 G catc! #File7otFound*"ce tion e"& S(stem.out. rintln#DHHH Cannot o en File&0 S(stem.e"it#&0 @@ /uit t!e rogram G

finall(in ut.close#&0

G


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Scanner Met!ods

'oolean !as7e"t ine#&String ne"t ine#&'oolean !as7e"t#&String ne"t#&'oolean !as7e"tInt#&int ne"tInt#&'oolean !as7e"t ou'le#&dou'le ne"t ou'le#&,oid close#&

eads one

ord


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riting to a e"t File String at!name Dout ut.t"tD0 File file ne File# at!name&0 5rint riter out ut null0 try

out ut ne 5rint riter# file&0 G catch #File7otFound*"ce tion e"& S(stem.out. rintln#DCannot create D K at!name&0 S(stem.e"it#1&0 @@ /uit t!e rogram G out ut. rintln#$an( data%&0out ut.flus!#&0out ut.close#&0

e/uired to flus!t!e out ut 'uffer

java streams n filing

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