TechAlpine – Txog tej Technology

Cas cov cim xeeb yog tswj nyob rau hauv java?

Nco qas ntsoov Java kev tuav lub thiab de-lub twb tau eliminated. Cim xeeb nyob rau hauv Java no yeej khib nyiab ntim kom tau koj yeej tsis txhawj txog kev nco kev noj nyiaj txiag. Java nco yog tswj los ntawm tus qauv nco. Tus qauv Java nco qauv piav txog synchronization txheej txheem kom paub tseeb tias cov ntaub ntawv kev noj nyiaj txiag tsis muab qhov chaw. Synchronization kuj yuav pab kom tsis txhob deadlocks ntawm threads thiab khiav programs smoothly. Cov kev tswj nram qab no muab ib overview ntawm java nco.

Muaj inheritances ntau zaum hauv java?

Tsis yog, ntau ncaus no tsis tau java. Interface muaj tau nkag tau rau lub hom phiaj thiab nws twb tau derived ntawm Objective C.

Yog vim li cas rau omitting ntau inheritances los ntawm cov lus Java language feem coob ntawm tus “yooj yim, kwv oriented thiab paub” lub hom phiaj. Ua ib hom lus yooj yim, Java tus creators xav tau ib hom lus uas feem coob developers yuav tuav tsis kim heev. Los ntawd xaus, lawv ua hauj lwm kom tau cov lus zoo ib yam li C tau li (paub zoo) tsis muaj nqa pem C tus tsis txaus siab complexity (yooj yim).

Nyob rau hauv cov designers’ tswvyim, ntau zaus ua teeb meem ntau yam thiab tsis meej pem li nws solves. Li ntawd, lawv hlais ntau inheritances los ntawm cov lus (thaum lawv txiav neeg teb xov tooj overloading). Lub designers’ Kim C kev qhia tau lawv tias muaj ntau yam inheritances cia li tsis tsim nyog lub taub hau.

Xwb, Java tus designers xaiv pub ntau interface interface los ntawm kev siv interfaces, ib lub tswv yim borrowed ntawm Objective C lub protocols. Ntau yam interface interface pub rau ib yam khoom rau inherit ntau ntau hom kev kos npe nrog lub caveat uas cov khoom inheriting yuav tsum siv cov kev phiv cov kev phiv.









Yog dab tsi tsim hom phiaj ntawm java?

Tom qab no yog cov qauv tsim hom phiaj ntawm java programming lus. Java designers muaj accomplished ua hauj lwm los kom cov hom phiaj nyob rau hauv siab.

• yooj yim
• Chaw nres nkoj
• Yam Ntxwv Nkaus
• txhais lus
• faib
• Kev kawm siab
• Robust
• Multithreaded
• ruaj ntseg
• Dynamic
• Architecture Neutral

Vim li cas java hu ua distributed?

Java muaj ib txoj kev tsev qiv ntawv uas niaj zaus rau tuav TCP/IP/IP cov protocols xws li HTTP thiab FTP. Li ntawd, Java applications yuav qhib thiab khoom thoob hauv internet ntawm URLs. Lub network programming siv java muaj zog thiab yooj yim rau siv. Li ntawd, java hu ua distributed.

Qhov xwm ntawm Java yeej ntsaws ci thaum tag nrho nrog nws hoob kawm dynamic loading capabilities. ua ke, Cov nta kom nws tau ib tug neeg txhais lus Java mus download thiab khiav tawm hauv internet. Qhov no yog li cas thaum ib Web browser downloads thiab sau ib kua txiv Java applet, Piv txwv. Scenarios yuav nyuab dua qhov no, Txawm li cas los. Xav txog tej yam ib txuj kev nyuaj-tawm lo lus sau hauv Java. Thaum twg qhov kev pab cuam no yog kom muab tej ntaub ntawv uas nws twb yeej tsis ces yuav tsum tau ces yuav tsum tau ua ntej, Nws yuav dynamically download ib hoob kawm los ntawm lub network uas yuav parse cov ntaub ntawv, thiab ces dynamically download lwm hoob kawm (tej zaum ib Java “taum”) uas yuav tso saib tau cov ntaub ntawv nyob rau hauv ib cov ntaub ntawv compound. Ib qhov kev pab cuam li no siv faib cov chaw muab kev pab rau lub network rau dynamically loj hlob thiab pab kom cov kev xav tau ntawm nws cov neeg siv.

Vim li cas java hu ua architecture neutral?

Java compiler generates ib bytecode qhia uas yog ywj siab ntawm lub computer architecture. Lub bytecode yog tsim los ua ob yooj yim rau txhais lus rau tej lub tshuab thiab yooj yim txhais ua cuaj cav tov rau hauv lub cav tov. Cov lus nram qab no qhia tau hais tias cov lus nthuav qhia li cas nws tej hauj lwm.

Vim li cas java enabled browser yuav tsum tau khiav ib cov kua?

Kua yog ib qhov kev pab cuam java uas ua haujlwm rau ib lub web sab. Li ntawd, tus browser yuav tsum muaj lub peev xwm txhais tau cov bytecode thiab ua nws ua hauj lwm. Yog vim li cas java enabled browser yuav tsum khiav ib lub kua embedded nyob rau hauv ib lub web sab. Ua tau tus browser muaj cov JVM inbuilt uas yuav pab txhais cov code thiab qhia cov zis.

Koj txhais li cas los ntawm 'Java yog ib hom lus typed nruab nrab'?

Java yog xav typed txhais tau hais tias txhua yam variable hauv java yuav tsum muaj ib hom. Muaj ntau yim txheej xwm rau Java. Plaub leeg muaj integer ntau hom thiab ob yog floating-taw tes ntau hom. Ib tug yog cov ua cim char, siv rau cov cim hauv lub Unicode encoding thiab ib tug yog ib hom Boolean rau qhov tseem ceeb.









Li cas kuv/O yog tswj nyob rau hauv java?

Nyob rau hauv java I/O nruab nrab yog input thiab tso zis kwj. Streams siv los yog sau ntawv mus rau li ntaub ntawv xws li tes hauj lwm los yog network los yog console. Java.io pob khoom rau kuv/O chav kawm ntawv rau manipulate streams. Qhov pob nyiaj them yug ob hom ntawm streams – binary streams uas kov cov ntaub ntawv binary thiab cov ua cim streams uas kov cov ua cim. InputStream thiab OutputStream muaj siab interfaces rau manipulating binary streams. Nyeem thiab txawj sau ntawv muaj kev cuam tshuam rau manipulating cim streams.

Cov nram qab no qhia tau hais tias txoj kev sib raug zoo ntawm cov IO chav kawm ntawv nyob rau hauv tshooj no

Li cas yog buffered kwj txhim khu kev kawm nyob rau hauv java?

Lub neej ntawd tus cwj pwm ntawm ib kwj yog nyeem los yog sau ib lub sij hawm. Qhov no ua rau kuv/O kev kawm vim hais tias nws yuav siv sij hawm ntau nyeem/sau ntawv los ntawm kev koom ua ke thaum soj ntsuam nrog cov ntaub ntawv loj loj ntawm cov ntaub ntawv. Java I/O muab Buffered streams rau override no los ntawm cov cwj pwm uas tsim nyog. Koj yuav tsum tau siv Buffered streams (BufferedInputream thiab BufferedOutStream) buffer cov ntaub ntawv thiab ces nyeem/sau ntawv uas muab kev kawm zoo. Koj yuav tsum to taub txog txoj kev vim tus cwj pwm coj thiab ua li ntawd.

Daim duab nram qab no qhia li cas buffered streams divert cov ntaub ntawv ntws.

Duab 4: Buffered streams

Yuav ua li cas koj ntsuas kev kawm ntawm tus cwj pwm coj thiab buffering rau cov ntaub ntawv nyeem ntawv?

Cov nram qab no snippet yuav siv cov ntaub ntawv zoo sib xws thiab sau ntawv siv cov nyeem ntawv thiab buffered nyeem ntawv. Thiab ces nws yuav tso saib lub sij hawm noj los ntawm ob leeg. Kev ntsuam xyuas qhov chaws no cia cov ntaub ntawv nyob rau hauv lawv cov ntaub ntawv raws li qhia hauv qab no.

Qhia 1: Buffering rau daim ntawv nyeem ntawv

pob khoom com.performance.io;

ntshuam java.io.*;

Pej xeem hoob kawm IOTest {

pej xeem tsis muaj dabtsis loj zoo li qub(Txoj hlua[] args){

IOTest io = tshiab IOTest();

sim{

Pib ntev = System.tam sim no();

io.readwrite(“c:/temp/test-origin.html”,”c:/temp/test-destination.html”);

Kawg endtime = System.tam sim no();

System.out.println(“Lub sij hawm noj nyeem ntawv thiab sau ntawv siv behaviour : ”

+ (kawg – pib) + ” milli vib nas” );

System startime = System.tam sim no();

io.readWriteBuffer(“c:/temp/test-origin.html”,”c:/temp/test-destination.html”);

Endtime1 = System.tam sim no();

System.out.println(“Lub sij hawm noj rau nyeem ntawv thiab sau ntawv siv buffered streams : ”

+ (kawg – pib) + ” milli vib nas” );

}ntes(IOException e){ e.printStackTrace();}

}

Pej xeem txheeb cais tawm nyeem(txoj hlua fileFrom, NTAIV) throws IOException{

InputStream hauv = null;

Outputream = null;

sim{

hauv = FileInStream(filefrom);

tawm = Fileoutputream tshiab(ntaub ntawv);

Thaum(tseeb){

nyeem tshwm sim = nyob rau hauv.nyeem();

Yog hais tias(bytedata == -1)

so;

out.Write(nruab nrab);

}

}

ntes(Kos e)

{

e.printStackTrace();

}

thaum kawg{

Yog hais tias(nyob rau hauv != thov)

nyob ze();

Yog hais tias(tawm != thov)

out.close();

}

}

pej xeem txheej txheem nyeem readWriteBuffer(txoj hlua fileFrom, NTAIV) throws IOException{

InputStream inBuffer = null;

Outputream outBuffer = null;

sim{

Inputstream hauv = FileInStream(filefrom);

Inbuffer = tshiab BufferedInStream(nyob rau hauv);

Outputream = tshiab FileoutStream(ntaub ntawv);

outbuffer = tshiab BufferedoutUtstream(tawm);

Thaum(tseeb){

Intedata = inBuffer.nyeem();

Yog hais tias(bytedata == -1)

so;

out.Write(nruab nrab);

}

}

ntes(Kos e)

{

e.printStackTrace();

}

thaum kawg{

Yog hais tias(inBuffer != thov)

inBuffer.ze ntawm();

Yog hais tias(outBuffer != thov)

outBuffer.ze ntawm();

}

}

)