Ka Java Si arụ ọrụ na Nghọta Usoro Usoro Java - Akụkụ 2
Na post ikpeazụ anyị 'Gịnị bụ Java na akụkọ ihe mere eme nke Java'anyị kpuchiri ihe bụ Java, atụmatụ Java na nkọwa, akụkọ ntọhapụ na aha ya yana ebe ejiri Java mee ihe.
N'ebe a na post a, anyị ga-aga site na ịrụ ọrụ na koodu nhazi nke asụsụ mmemme Java. Tupu anyị aga n'ihu ka m chetara gị na e mepụtara Java na-eburu n'uche Dee otu ugboro na-agba ọsọ n'ebe ọ bụla/oge ọ bụla (WORA) pụtara ịhụ na ngwa e mepụtara kwesịrị ịdị na-anọpụ iche nke ụlọ, Platform Independent and mobile.
Java na-arụ ọrụ
N'iburu ihe mgbaru ọsọ ndị a n'uche ka emepụtara Java site n'ụdị ọrụ dị n'okpuru ebe enwere ike kewaa n'ime nkeji anọ.
Dee faịlụ isi mmalite. Faịlụ a nwere usoro, usoro, klaasị na ihe niile dị n'ime ụkpụrụ akwadoro maka Asụsụ Mmemme Java. Aha faịlụ isi iyi kwesịrị ịbụ aha klaasị ma ọ bụ nke ọzọ. Aha faịlụ isi iyi ga-enwerịrị ndọtị .java. Ọzọkwa aha faịlụ na aha klaasị nwere mmetụta ikpe.
Gbaa faịlụ Java Source Code site na Java Compiler. Koodu Java Source Compiler na-enyocha njehie na syntax na faịlụ isi mmalite. Ọ gaghị ekwe ka ị chịkọta koodu isi mmalite gị na-enweghị afọ ojuju Java compiler site na idozi njehie na ịdọ aka ná ntị niile.
Compiler na-emepụta faịlụ klas. Faịlụ klas ndị a na-eketa otu aha dị ka aha faịlụ koodu isi mmalite, mana ndọtị ahụ dịgasị iche. Aha faịlụ Isi Iyi nwere ndọtị filename.java, ebe ndọtị nke klasfile mepụtara site na mkpokọta bụ filename.class. Edebere faịlụ klas a n'ime bytecode - bytecode dị ka anwansi.
Faịlụ klas a nke Java Compiler mebere bụ obere na-anọpụ iche na ụkpụrụ ụlọ. Ị nwere ike ibubata faịlụ klas a ka ọ rụọ ọrụ na nhazi nhazi ọ bụla yana Platform/ngwaọrụ. Naanị ihe ịchọrọ bụ igwe Java Virtual (JVM) iji mee koodu a n'agbanyeghị ebe.
Ugbu a ghọta usoro anọ dị n'elu site na iji ihe atụ. Nke a bụ obere koodu mmemme Java. Echegbula onwe gị ma ọ bụrụ na ị ghọtaghị koodu dị n'okpuru. Dị ka nke ugbu a dị nnọọ ịghọta otú o si arụ ọrụ.
public class MyFirstProgram
{
public static void main(String[] args)
{
System.out.println("Hello Tecmint, This is my first Java Program");
}
}
1. Edere m mmemme a ma kọwaa aha klas MyFirstProgram. Ọ dị mkpa ịmara na a ga-echekwa mmemme a ka MyFirstProgram.java.
Cheta ọkwa 1 dị n'elu - Aha klaasị na aha faịlụ ga-abụrịrị otu na aha faịlụ ga-enwerịrị ndọtị .java. Ọzọkwa Java na-enwe mmetụta nke ukwuu ma ọ bụrụ na aha klas gị bụ 'MyFirstProgram', aha faịlụ gị ga-abụrịrị 'MyFirstProgram.java'.
Ị nweghị ike ịkpọ ya 'Myfirstprogram.java' ma ọ bụ 'myfirstprogram.java' ma ọ bụ ihe ọ bụla ọzọ. Site na nkwekọrịta ọ dị mma ịkpọ klas gị aha dabere n'ihe mmemme na-eme n'ezie.
2. Iji chịkọta faịlụ Java Source a, ị ga-ebufe ya site na mkpokọta Java. Ndị nchịkọta Java ga-elele koodu isi mmalite maka njehie na ịdọ aka ná ntị ọ bụla. Ọ gaghị achịkọta koodu isi mmalite ruo mgbe edoziri nsogbu niile. Iji chịkọta koodu isi mmalite java, ịkwesịrị ịgba ọsọ:
$ javac MyFirstProgram.java
Ebe MyFirstProgram.java bụ aha faịlụ isi mmalite.
3. Na nchịkọta nke ọma, ị ga-achọpụta na Java compiler kere faịlụ ọhụrụ n'ime otu ndekọ aha ya bụ MyFirstProgram.class.
A na-edobe faịlụ klas a na bytecodes ma nwee ike ịgba ọsọ n'elu ikpo okwu ọ bụla, nhazi nhazi ọ bụla nke oge ọ bụla. Ị nwere ike ịme faịlụ klaasị n'ime JVM (Java Virtual Machine) na Linux ma ọ bụ ihe ọ bụla ọzọ dị ka:
$ java MyFirstProgram
Yabụ na enwere ike ịchịkọta ihe niile ị mụtara n'elu dịka:
Java Source Code >> Compiler >> classfile/bytecode >> Various devices running JVM
Ịghọta Ọdịdị Usoro na Java
1. Faịlụ koodu iyi Java ga-enwerịrị nkọwa klaasị. Otu faịlụ Java nwere ike ịnwe naanị otu klaasị ọha/ọkwa dị elu mana ọ nwere ike ịnwe ọtụtụ klaasị nkeonwe/klaasị ime.
Klas dị n'èzí/klas kacha elu/klaasị ọha nwere ike ịnweta klaasị nkeonwe/klaasị ime. Klas ahụ ga-abụrịrị n'ime ihe nkwado gbagọrọ agbagọ. Ihe niile dị na Java bụ ihe na klaasị bụ ụkpụrụ maka ihe.
Ihe ngosi nke klaasị ọha/onwe na Java:
public class class0
{
...
private class1
{
…
}
private class 2
{
…
}
...
}
2. Klas nwere otu ụzọ ma ọ bụ karịa. Usoro ga-agarịrị n'ime ihe nkwado mgbako nke klaasị. Ọmụmaatụ dummy bụ:
public class class0
{
public static void main(String[] args)
{
…..
…..
}
}
3. Usoro nwere otu nkwupụta/ntụziaka ma ọ bụ karịa. Ntuziaka(s) ga-abanyerịrị n'ime nkwado nkwado nke usoro. Ọmụmaatụ dummy bụ:
public class class0
{
public static void main(String[] args)
{
System.out.println("Hello Tecmint, This is my first Java Program");
System.out.println("I am Loving Java");
…
...
}
}
Ọ dịkwa mkpa ịkọwa n'oge a - Nkwupụta ọ bụla ga-ejedebe na semicolon. Ọmụmaatụ dummy bụ:
System.out.println("Hello Tecmint, This is my first Java Program");
...
...
System.out.println("I am Loving Java");
Iji nkọwa zuru ezu dee mmemme Java mbụ gị. A na-etinye nkọwa a ka ọ bụrụ nkwupụta ebe a (// pụtara nkọwapụta) n'ihe atụ a. Ị ga-ede nkọwa n'ime mmemme.
Ọ bụghị naanị n'ihi na nke a bụ àgwà dị mma kamakwa n'ihi na ọ na-eme ka koodu ahụ gụọ ab gị ma ọ bụ onye ọ bụla ọzọ n'oge ọ bụla ma emechaa.
// Declare a Public class and name it anything but remember the class name and file name must be same, say class name is MyProg and hence file name must be MyProg.java
public class MyProg
// Remember everything goes into curly braces of class?
{
// This is a method which is inside the curly braces of class.
public static void main(String[] args)
// Everything inside a method goes into curly braces
{
// Statement or Instruction inside method. Note it ends with a semicolon
System.out.println("I didn't knew JAVA was so much fun filled");
// closing braces of method
}
// closing braces of class
}
Nkọwa teknụzụ zuru ezu nke mmemme Java dị n'elu dị mfe.
public class MyProg
N'ebe a na aha klaasị dị n'elu bụ MyProg na MyProg bụ klaasị ọha nke pụtara na onye ọ bụla nwere ike ịnweta ya.
public static void main(String[] args)
N'ebe a aha usoro bụ isi nke bụ usoro ọha, pụtara na onye ọ bụla nwere ike ịnweta ya. Ụdị nloghachi bụ ihe efu nke pụtara enweghị uru nloghachi. string[] args pụtara arụmụka maka usoro isi kwesịrị ịbụ array nke a ga-akpọ args. Echegbula onwe gị maka ihe 'static' pụtara ugbu a. Anyị ga-akọwa n'ụzọ zuru ezu banyere ya mgbe achọrọ.
System.out.println("I didn't knew JAVA was so much fun filled");System.out.ln rịọ JVM ka o bipụta mmepụta na mmepụta ọkọlọtọ nke bụ Line Line Line n'ọnọdụ anyị. Ihe ọ bụla dị n'etiti nkwado nkwado nke nkwupụta println na-enweta ebipụta ka ọ dị, ma ọ bụrụ na ọ bụ mgbanwe. Anyị ga-abanye na nkọwa nke mgbanwe ma emechaa. Okwu a na-ejedebe na semicolon.
Ọbụna ma ọ bụrụ na ihe edoghị anya ugbu a, ịkwesighi ichegbu onwe gị maka nke a. Ọzọkwa ịkwesighi icheta ihe ọ bụla. Naanị gaa na post ahụ wee ghọta okwu na-arụ ọrụ ọbụlagodi mgbe foto ahụ edoghị anya.
Nke ahụ bụ ihe niile ugbu a. Jikọọ na Tecmint. Nye anyị nzaghachi gị bara uru na nkwupụta n'okpuru. Anyị na-arụ ọrụ na akụkụ na-esote klas na usoro Main na Java a ga-ebipụta ya n'oge adịghị anya.