Java yog hom lus-hom lus programming tsim nyob rau xyoo 1995 los ntawm James Gosling, uas txhais tau tias nws sawv cev cov ntsiab lus ua "khoom" nrog "cov teb" (uas yog tus cwj pwm uas piav qhia txog lub hom phiaj) thiab "cov txheej txheem" (kev ua uas lub hom phiaj tuaj yeem ua tau). Java yog "sau ib zaug, khiav txhua qhov chaw" lus, uas txhais tau tias nws tau tsim los khiav ntawm txhua lub platform uas muaj Java Virtual Machine (JVM). Txij li Java yog ib hom lus siv ntau lub ntsiab lus, nws yooj yim rau cov pib kawm thiab nkag siab. Phau ntawv qhia no yog qhia txog kev sau cov haujlwm hauv Java.
Cov kauj ruam
Txoj Kev 1 ntawm 3: Sau Koj Thawj Java Program
Kauj Ruam 1. Txhawm rau pib sau cov haujlwm hauv Java, teeb tsa koj qhov chaw ua haujlwm
Ntau tus programmer siv Kev Txhim Kho Ib puag ncig ib puag ncig (IDEs) xws li dab noj hnub thiab Netbeans rau lawv qhov kev tsim kho Java, tab sis ib tus tuaj yeem sau Java program thiab suav nws yam tsis muaj IDEs.
Kauj Ruam 2. Txhua yam ntawm Notepad-like program yuav txaus rau kev ua haujlwm hauv Java
Hardcore programmers qee zaum nyiam siv cov ntawv kho uas nyob hauv lub davhlau ya nyob twg xws li vim thiab emacs. Cov ntawv nyeem zoo heev uas tuaj yeem teeb tsa ntawm ob lub tshuab Windows thiab ntawm lub tshuab linux-based (Mac, Ubuntu, thiab lwm yam) yog Sublime Text, uas yog yam peb yuav siv hauv qhov kev qhia no.
Kauj Ruam 3. Nco ntsoov tias koj tau teeb tsa Java Software Development Kit
Koj yuav xav tau qhov no los suav koj qhov program.
-
Hauv Windows-based operating system, yog tias ib puag ncig hloov pauv tsis raug, koj yuav tau txais qhov yuam kev thaum khiav
javac ua
- . Xa mus rau kab lus teeb tsa Yuav Ua Li Cas Txhim Kho Java Software Development Kit kom paub meej ntxiv txog JDK teeb tsa kom tsis txhob muaj qhov yuam kev no.
Txoj Kev 2 ntawm 3: Nyob Zoo Hauv Ntiaj Teb
Kauj Ruam 1. Peb yuav xub tsim qhov program uas luam tawm "Nyob Zoo Ntiaj Teb
"Hauv koj cov ntawv sau, tsim cov ntawv tshiab thiab khaws nws li" HelloWorld.java ". HelloWorld yog koj lub npe chav kawm thiab koj yuav xav tau koj lub npe chav kawm kom zoo ib yam li koj cov ntaub ntawv.
Kauj Ruam 2. Tshaj tawm koj chav kawm thiab koj txoj hauv kev tseem ceeb
Txoj hauv kev tseem ceeb
pej xeem zoo li qub tsis muaj dab tsi tseem ceeb (Txoj hlua args)
yog txoj hauv kev uas yuav ua tiav thaum lub phiaj xwm ua haujlwm. Txoj hauv kev tseem ceeb no yuav muaj tib txoj kev tshaj tawm hauv txhua txoj haujlwm Java.
public class HelloWorld {pej xeem zoo li qub tsis muaj dab tsi tseem ceeb (Txoj hlua args) {}}
Kauj Ruam 3. Sau kab kab ntawv uas yuav luam tawm "Nyob Zoo Ntiaj Teb
System.out.println ("Nyob Zoo Ntiaj Teb.");
-
Cia peb saib cov khoom ntawm kab no:
-
Txheej txheem
- qhia rau lub system kom ua ib yam dab tsi.
-
tawm
- qhia rau lub system tias peb yuav ua qee yam khoom tso tawm.
-
println
- sawv rau "print line," yog li peb tab tom qhia rau lub kaw lus kom luam kab hauv kab ntawv.
-
Cov niam txiv nyob ib puag ncig
("Nyob zoo ntiaj teb.")
txhais tau tias txoj kev
System.out.println ()
siv nyob rau hauv qhov ntsuas, uas, hauv qhov no, yog Txoj hlua
"Nyob Zoo Ntiaj Teb."
-
-
Nco tseg tias muaj qee txoj cai hauv Java uas peb yuav tsum ua raws:
- Koj yuav tsum tau ntxiv ib semicolon tom kawg ntawm txhua kab.
- Java yog cov ntaub ntawv rhiab, yog li koj yuav tsum sau cov npe txheej txheem, cov npe sib txawv, thiab cov npe hauv chav hauv qhov raug lossis koj yuav tau txais qhov yuam kev.
- Cov thaiv ntawm cov cai tshwj xeeb rau qee txoj hauv kev lossis lub voj raug kaw ntawm cov kab zauv.
Kauj Ruam 4. Muab tag nrho ua ke
Koj qhov program Hello World kawg yuav tsum zoo li cov hauv qab no:
pej xeem chav HelloWorld {pej xeem zoo li qub tsis muaj dab tsi tseem ceeb (Txoj hlua args) {System.out.println ("Nyob Zoo Ntiaj Teb."); }}
Kauj Ruam 5. Khaws koj cov ntaub ntawv thiab qhib qhov hais kom sai lossis davhlau ya nyob twg los sau cov haujlwm
Nkag mus rau daim nplaub tshev uas koj tau cawm HelloWorld.java thiab ntaus hauv
javac HelloWorld.java
. Qhov no qhia rau Java compiler uas koj xav suav sau HelloWorld.java. Yog tias muaj qhov ua yuam kev, tus sau ntawv yuav qhia koj tias koj tau ua tsis raug. Txwv tsis pub, koj yuav tsum tsis txhob pom ib qho lus los ntawm tus sau. Yog tias koj saib cov npe uas koj muaj HelloWorld.java tam sim no, koj yuav tsum pom HelloWorld.class. Nov yog cov ntaub ntawv uas Java yuav siv los khiav koj txoj haujlwm.
Kauj Ruam 6. Khiav qhov program
Thaum kawg, peb tau khiav peb qhov program! Hauv qhov hais kom ua lossis lub davhlau ya nyob twg, ntaus hauv
java HelloWorld
. Qhov no qhia Java tias koj xav khiav chav HelloWorld. Koj yuav tsum pom "Nyob Zoo Ntiaj Teb." qhia tawm hauv koj lub console.
Kauj Ruam 7. Nrog koj zoo siab, koj tau ua koj thawj Java program
Txoj Kev 3 ntawm 3: Kev Tawm Tswv Yim thiab Kev Tso Tawm
Kauj Ruam 1. Tam sim no peb yuav txuas ntxiv peb qhov Hello World program kom nkag siab los ntawm tus neeg siv
Hauv peb Txoj Haujlwm Zoo Nyob Hauv Ntiaj Teb, peb tau luam tawm ib txoj hlua rau tus neeg siv pom, tab sis kev sib tham ib feem ntawm cov phiaj xwm yog thaum tus neeg siv nkag mus nkag rau hauv txoj haujlwm. Tam sim no peb yuav txuas ntxiv peb txoj haujlwm kom sai rau tus neeg siv rau nws lub npe thiab tom qab ntawd tos txais tus neeg siv los ntawm nws lub npe.
Kauj ruam 2. Ntshuam chav kawm Scanner
Hauv Java, peb muaj qee qhov ua hauv cov tsev qiv ntawv uas peb nkag tau, tab sis peb yuav tsum tau import lawv. Ib ntawm cov tsev qiv ntawv no yog java.util, uas muaj cov Scanner kwv uas peb xav tau kom tau txais cov neeg siv khoom nkag. Txhawm rau ntshuam chav kawm Scanner, peb ntxiv kab hauv qab no rau qhov pib ntawm peb cov cai.
ntshuam java.util. Scanner;
- Qhov no qhia peb txoj haujlwm uas peb xav siv lub Scanner yam khoom uas muaj nyob hauv pob java.util.
-
Yog tias peb xav kom nkag tau rau txhua qhov khoom hauv java.util pob, peb sau yooj yim
ntshuam java.util.*;
- thaum pib ntawm peb cov cai.
Kauj Ruam 3. Sab hauv peb txoj hauv kev tseem ceeb, ua kom pom qhov tshiab ntawm Scanner yam khoom
Java yog hom lus-hais lus programming, yog li nws sawv cev cov ntsiab lus siv cov khoom. Lub Hom Phiaj Scanner yog piv txwv ntawm cov khoom uas muaj cov haujlwm thiab cov hau kev. Txhawm rau siv chav kawm Scanner, peb yuav tsum tsim lub Scanner tshiab yam khoom uas peb tuaj yeem ua rau thaj tsam ntawm thiab siv cov txheej txheem ntawm. Txhawm rau ua qhov no, peb sau:
Scanner userInputScanner = Scanner tshiab (System.in);
-
userInputScanner
- yog lub npe ntawm Scanner object uas peb nyuam qhuav ua tiav. Nco ntsoov tias lub npe tau sau rau hauv rooj plaub ntxhuav; qhov no yog qhov kev pom zoo rau npe hloov pauv hauv Java.
-
Peb siv lub
tshiab
tus neeg teb xov tooj los tsim qhov piv txwv tshiab ntawm ib qho khoom. Yog li, hauv qhov piv txwv no, peb tsim qhov piv txwv tshiab ntawm Scanner kwv los ntawm kev sau ntawv
Tshiab Scanner (System.in)
- .
-
Cov khoom siv Scanner siv nyob rau hauv qhov ntsuas uas qhia lub hom phiaj dab tsi los luam theej duab. Hauv qhov no, peb muab tso rau hauv
System.in ua
raws li qhov ntsuas.
System.in ua
- qhia qhov kev zov me nyuam txhawm rau tshuaj xyuas cov tswv yim los ntawm kab ke, uas yog cov tswv yim uas tus neeg siv yuav ntaus rau hauv txoj haujlwm.
Kauj Ruam 4. Hais kom tus neeg siv nkag mus
Peb yuav tsum tau hais kom tus neeg siv nkag mus kom tus neeg siv paub thaum twg yuav ntaus ib yam dab tsi rau hauv lub console. Qhov no tuaj yeem ua tiav nrog a
System.out.print
los yog a
System.out.println
System.out.print ("Koj lub npe hu li cas?");
Kauj Ruam 5. Nug lub Scanner kwv mus rau kab tom ntej uas tus neeg siv ntaus hauv thiab khaws qhov ntawd hauv qhov sib txawv
Lub Tshuab Luam Ntawv yuav ib txwm ua cov ntaub ntawv ntawm tus neeg siv tau ntaus dab tsi. Cov kab hauv qab no yuav nug tus Scanner coj tus neeg siv tau ntaus rau nws lub npe thiab khaws nws hauv qhov sib txawv:
Txoj hlua userInputName = userInputScanner.nextLine ();
-
Hauv Java, qhov kev pom zoo rau kev siv tus txheej txheem txheej txheem yog
objectName.methodName (tsis)
. Hauv
userInputScanner.nextLine ()
peb tab tom hu peb lub Scanner kwv los ntawm lub npe peb tsuas yog muab rau nws thiab tom qab ntawd peb tab tom hu nws txoj kev
tom ntejLine ()
- uas tsis coj mus rau hauv ib qho kev ntsuas.
-
Nco ntsoov tias peb tab tom khaws kab tom ntej hauv lwm yam khoom: Cov khoom siv hlua. Peb tau muab peb lub npe String object
userInputName
Kauj Ruam 6. Luam tawm kev txais tos rau tus neeg siv
Tam sim no peb muaj tus neeg siv lub npe khaws cia, peb tuaj yeem luam tawm cov lus txais tos rau tus neeg siv. Nco txog
System.out.println ("Nyob Zoo Ntiaj Teb.");
uas peb tau sau hauv chav kawm tseem ceeb? Txhua qhov chaws uas peb nyuam qhuav sau yuav tsum mus saum kab ntawv ntawd. Tam sim no peb tuaj yeem hloov kho kab ntawd kom hais:
System.out.println ("Nyob zoo" + userInputName + "!");
-
Txoj kev uas peb txuas nrog "Nyob Zoo", tus neeg siv lub npe, thiab "!" los ntawm kev sau ntawv
"Nyob zoo" + userInputName + "!"
- hu ua String concatenation.
- Dab tsi tshwm sim ntawm no yog tias peb muaj peb txoj hlua: "Nyob zoo", userInputName, thiab "!". Cov hlua hauv Java tsis hloov pauv, uas txhais tau tias lawv tsis tuaj yeem hloov pauv. Yog li thaum peb tab tom sib txuas peb txoj hlua no, peb yeej tsim cov hlua tshiab uas muaj cov lus tos txais.
-
Tom qab ntawd peb coj txoj hlua tshiab no thiab pub nws ua qhov ntsuas rau
System.out.println
- .
Kauj Ruam 7. Muab tag nrho ua ke thiab txuag
Tam sim no peb cov cai yuav tsum zoo li no:
ntshuam java.util. Scanner; pej xeem chav HelloWorld {pej xeem zoo li qub tsis muaj dab tsi tseem ceeb (Txoj hlua args) {Scanner userInputScanner = tshiab Scanner (System.in); System.out.print ("Koj lub npe hu li cas?"); Txoj hlua userInputName = userInputScanner.nextLine (); System.out.println ("Nyob zoo" + userInputName + "!"); }}
Kauj Ruam 8. Sau thiab khiav
Mus rau hauv qhov hais kom ua tam sim lossis lub davhlau ya nyob twg thiab khiav tib cov lus txib raws li peb tau khiav rau peb thawj zaug ntawm HelloWorld.java. Peb yuav tsum xub suav qhov program:
javac HelloWorld.java
. Tom qab ntawd peb tuaj yeem khiav nws:
java HelloWorld
Qauv Java Cov Kev Kawm
Qauv Qauv Java Program
Txhawb wikiHow thiab qhib tag nrho cov qauv.
Qauv Java Program nrog Kev Nkag Mus
Txhawb wikiHow thiab qhib tag nrho cov qauv.
Lub tswv yim
- Java yog hom lus-hom lus programming, yog li nws muaj txiaj ntsig zoo los nyeem ntxiv ntawm lub hauv paus ntawm hom phiaj-hais lus hom lus.
-
Lub Hom Phiaj Kev Taw Qhia muaj ntau yam tshwj xeeb rau nws cov qauv. Peb ntawm cov yam ntxwv tseem ceeb no yog:
- Encapsulation: muaj peev xwm txwv tsis pub nkag mus rau qee yam khoom siv. Java muaj tus kheej, tiv thaiv, thiab hloov kho pej xeem rau cov haujlwm thiab cov hau kev.
- Polymorphism: lub peev xwm rau cov khoom coj los ntawm tus kheej sib txawv. Hauv Java, ib yam khoom tuaj yeem raug pov rau lwm yam khoom siv lwm yam khoom siv txoj hauv kev.
- Cov qub txeeg qub teg: lub peev xwm los siv cov teb thiab cov txheej txheem los ntawm lwm chav kawm hauv tib qib raws li cov khoom tam sim no.
