พื้นฐานภาษา java

»ÃÐÇÑµÔÀÒÉÒ JAVA

ÀÒÉÒ¨ÒÇÒ à»š¹ÀÒÉÒâ»Ãá¡ÃÁàªÔ§ÇÑµ¶Ø·Õè¾Ñ²¹Ò¢Öé¹â´Â Dr.James Gosling áÅÐ·ÕÁÇÔÈÇ¡Ã¢Í§à¢Ò «Öè§ºÃÔÉÑ· Sun Microsystems µŒÍ§¡ÒÃ¹íÒÀÒÉÒ¨ÒÇÒÁÒãªŒá·¹ÀÒÉÒ C++ ¨¹ã¹»‚ ¤.È. 1995 ÀÒÉÒ¨ÒÇÒàÃÔèÁà»š¹·Õè¹ÔÂÁá¾Ã‹ËÅÒÂ

¤ÇÒÁËÁÒÂÀÒÉÒ¨ÒÇÒ (Java Language)

ÀÒÉÒ¨ÒÇÒ (Java Language) ¤×Í ÀÒÉÒ¤ÍÁ¾ÔÇàµÍÃ�·Õè¶Ù¡¾Ñ²¹Ò¢Öé¹â´ÂºÃÔÉÑ· Sun Microsystems à»š¹ÀÒÉÒÊíÒËÃÑºà¢ÕÂ¹â»Ãá¡ÃÁ·ÕèÊ¹ÑºÊ¹Ø¹¡ÒÃà¢ÕÂ¹â»Ãá¡ÃÁàªÔ§ÇÑµ¶Ø (OOP : Object-Oriented Programming) â»Ãá¡ÃÁ·Õèà¢ÕÂ¹¢Öé¹¶Ù¡ÊÃŒÒ§ÀÒÂã¹¤ÅÒÊ Ñ§¹Ñé¹¤ÅÒÊ¤×Í·Õèà¡çºàÁ·Í´ (Method) ËÃ×Í¾ÄµÔ¡ÃÃÁ (Behavior) «Öè§ÁÕÊ¶Ò¹Ð (State) áÅÐÃÙ»¾ÃÃ³ (Identity) »ÃÐ¨íÒ¾ÄµÔ¡ÃÃÁ (Behavior)

Ø´à ‹¹¢Í§ÀÒÉÒ¨ÒÇÒ (Java Language)

1) à»š¹ÀÒÉÒÊíÒËÃÑº¡ÒÃà¢ÕÂ¹â»Ãá¡ÃÁàªÔ§ÇÑµ¶Ø (OOP: Object Oriented Programming)

2) Java ¤×Í platform independence ËÁÒÂ¤ÇÒÁÇ‹Ò ¤ÇÒÁÊÒÁÒÃ¶¢Í§â»Ãá¡ÃÁ·Õèà¢ÕÂ¹ ŒÇÂ java ÊÒÁÒÃ¶·íÒ§Ò¹ä Œã¹ ÃÐºº»¯ÔºÑµÔ¡ÒÃ·Õè µ‹Ò§¡Ñ¹ â´ÂäÁ‹µŒÍ§ Ñ´á»Å§á¡Œä¢ãËÁ‹

3) Free áÅÐ à»š¹â»Ãá¡ÃÁ»ÃÐàÀ· Open Source

ª¹Ô´¢Í§â»Ãá¡ÃÁ Java

1) Java Application

à»š¹¡ÒÃ¹íÒâ»Ãá¡ÃÁ Java ÁÒà¢ÕÂ¹à»š¹â»Ãá¡ÃÁ·ÕèÊÒÁÒÃ¶¹íÒÁÒãªŒ§Ò¹ä ŒÍÂ‹Ò§ÍÔÊÃÐª¹Ô´¢Í§â»Ãá¡ÃÁ Java

2) Java Applets

à»š¹¡ÒÃ¹íÒ Java ÁÒà¢ÕÂ¹à»š¹â»Ãá¡ÃÁàª‹¹à ÕÂÇ¡Ñ¹ áµ‹äÁ‹ÊÒÁÒÃ¶àÃÕÂ¡ãªŒ§Ò¹ä ŒµÒÁÅíÒ¾Ñ§ µŒÍ§¹íÒÁÒãÊ‹äÇŒã¹àÍ¡ÊÒÃ HTML áÅŒÇãªŒâ»Ãá¡ÃÁ Web Browser ËÃ×Í Utilities ¢Í§ Java à¾×èÍàÃÕÂ¡ Ù¼ÅÅÑ¾ �

â¤Ã§ÊÃŒÒ§ ÀÒÉÒ Java

µÑÇÍÂ‹Ò§àª‹¹ public class ª×èÍ¤ÅÒÊ

{ public static void main(String[] agrs) { »ÃÐâÂ¤¤íÒÊÑè§µ‹Ò§æ ¢Í§â»Ãá¡ÃÁ; ..................................................; } }


à¤Ã×èÍ§ËÁÒÂ ã¹¡ÒÃ¤Çº¤ØÁ Structure 1.1 Comment ¤×Í¢ŒÍ¤ÇÒÁ·Õèá·Ã¡à¢ŒÒä»ã¹â»Ãá¡ÃÁ áµ‹äÁ‹ÁÕ¼Åµ‹Í¡ÒÃ

·íÒ§Ò¹ ¢Í§â»Ãá¡ÃÁ àª‹¹ã¹¡Ã³Õ·ÕàÃÒµŒÍ§¡ÒÃÍ¸ÔºÒÂ Source code äÇŒã¹ â»Ãá¡ÃÁ ÇÔ¸Õ¡ÒÃ¤×Í

- comment ·ÕÅÐ ºÃÃ·Ñ´ãªŒà¤Ã×èÍ§ËÁÒÂ // µÒÁ´ŒÇÂ¢ŒÍ¤ÇÒÁ·ÕµŒÍ§¡ÒÃ comment

1.2 Keyword ¤×Í¤íÒ·Õ¶Ù¡¡íÒË¹´äÇŒãªŒàÍ§áÅŒÇã¹ÀÒÉÒ Java äÁ‹ÊÒÁÒÃ¶ ¹íÒÁÒãªŒã¹¡ÒÃµÑé§ª×èÍÀÒÂã¹â»Ãá¡ÃÁä´Œ µÑÇÍÂ‹Ò§àª‹¹ class,boolean,char à»š¹µŒ¹

1.3 Identifiers ¤×Íª×èÍ·Õè¼ÙŒà¢ÕÂ¹µÑé§¢Öé¹ÁÒ à¾×èÍãªŒá·¹ÍÐäÃ¡çä´ŒäÁ‹Ç‹Ò¨Ðà»š¹

method ,µÑÇá»Ã ËÃ×Í class ª×èÍ·Õè¶Ù¡µŒÍ§¤ÇÃ»ÃÐ¡Íº´ŒÇÂ µÑÇÍÑ¡ÉÃ ,µÑÇàÅ¢ ,_,$ áÅÐ¨ÐµŒÍ§¢Öé¹: µŒ¹´ŒÇÂµÑÇÍÑ¡ÉÃà·‹Ò¹Ñé¹


1.4 Separators ¤×Í ÍÑ¡ÉÃËÃ×Íà¤Ã×èÍ§ËÁÒÂ·ÕèãªŒáº‹§áÂ¡¤íÒã¹ÀÒÉÒ ÁÕ ´Ñ§µ‹Íä»¹Õé! - à¤Ã×èÍ§ËÁÒÂ () ãªŒÊíÒËÃÑº 1. µ‹Í·ŒÒÂª×èÍ method äÇŒãËŒãÊ‹ parameter àª‹¹ private void hello( ); 2. ÃÐºØà§×èÍ¹ä¢¢Í§ if , while , for ,do àª‹¹ if ( i=0 ) 3. ÃÐºØª×èÍ ª¹Ô´¢ŒÍÁÙÅã¹¡ÒÃ ·íÒ casting àª‹¹ String a=( String )x;


- à¤Ã×èÍ§ËÁÒÂ{ }ãªŒÊíÒËÃÑº

¡íÒË¹´¢Íºà¢µ¢Í§ method áÅÐ class

àª‹¹ class A{ }

Private void hello(){

}

2. ¡íÒË¹´¤‹ÒàÃÔÁµŒ¹ãËŒ ¡ÑºµÑÇá»Ã Array

àª‹¹ String a[]={"A","B","C"};


- à¤Ã×èÍ§ËÁÒÂ [ ] ãªŒÊíÒËÃÑº

1. ¡íÒË¹´µÑÇ á»Ãáºº Array

àª‹¹ String a[ ];

2. ¡íÒË¹´¤‹Ò index ¢Í§µÑÇ á»Ã array

àª‹¹ a[ 0 ]=10;

- à¤Ã×èÍ§ËÁÒÂ ; ãªŒà¾×èÍ »�´»ÃÐâÂ¤

àª‹¹ String a ;

- à¤Ã×èÍ§ËÁÒÂ , ãªŒÊíÒËÃÑº

1. áÂ¡ª×èÍµÑÇá»Ãã¹»ÃÐâÂ¤

àª‹¹ String a , b , c;

- à¤Ã×èÍ§ ËÁÒÂ . ãªŒÊíÒËÃÑº

1. áÂ¡ª×èÍ package, sub package áÅÐª×èÍclass

àª‹¹ package com.test.Test1;

2. ãªŒà¾×èÍ àÃÕÂ¡ãªŒ µÑÇ á»Ã ËÃ×Í method ¢Í§ Object

àª‹¹ object.hello();

àÁ¸Í´áÊ´§¼Å·Ò§¨ÍÀÒ¾¾×é¹°Ò¹

¡ÒÃÃÑº¢ŒÍÁÙÅ·Ò§¤ÕÂ�ºÍÃ�´ã¹ÀÒÉÒ¨ÒÇÒ¨ÐµŒÍ§ÊÃŒÒ§ÍÍºà ç¡µ�¢Í§

¤ÅÒÊ Scanner ¢Öé¹ÁÒâ´Â¨ÐµŒÍ§»ÃÐ¡ÒÈµÑÇá»ÃÍÍºà ç¡µ�¡‹Í¹ àª‹¹ Scanner keyboard; »ÃÐ¡ÒÈµÑÇá»ÃÍÍºà ç¡µ�ª×èÍ keyboard ÍÂÙ‹ã¹¤ÅÒÊ Scanner ¨Ò¡¹Ñé¹µŒÍÊÃŒÒ§ÍÍºà ç¡µ�

ÁÒâ´ÂãªŒ¤ÕÂ�àÇÔÃ�´ new ÁÕÃÙ»áºº´Ñ§¹Õé µÑÇá»ÃÍÍºà ç¡µ� = new ª×èÍ¤ÅÒÊ(ÍÒÃ�¡ÔÇàÁ¹µ�); ´Ñ§¹Ñé¹¶ŒÒ¨ÐãËŒµÑÇá»Ã keyboard ÃÑº¤‹Ò·Ò§á»‡¹¾ÔÁ¾�¨ÐµŒÍ§ÊÃŒÒÍÍºà¨ç¡µ�¢Öé¹ÁÒâ´Â

ãËŒÁÕÍÒÃ�¡ÔÇàÁ¹µ�à»š¹ System.in ´Ñ§¹Õé keyboard = new Scanner(System.in);

ã¹¤ÅÒÊ Scanner ¹Ñé¹àÁ¸Í´ÊíÒËÃÑºÍ‹Ò¹¢ŒÍÁÙÅ»ÃÐàÀ·µ‹Ò§æËÅÒÂ»ÃÐàÀ· ´Ñ§¹Õé

àÁ¸Í´ÊíÒËÃÑºÍ‹Ò¹¢ŒÍÁÙÅ»ÃÐàÀ·µ‹Ò§æ

àÁ¸Í´ ¡ÒÃ·íÒ§Ò¹

nextByte() ÃÑº¢ŒÍÁÙÅàÅ¢¨Ò¹Ç¹àµçÁª¹Ô´ Byte ·Ò§á»‡¹¾ÔÁ¾�

nextDouble() ÃÑº¢ŒÍÁÙÅàÅ¢·È¹ÔÂÁª¹Ô´ Double ·Ò§á»‡¹¾ÔÁ¾�

nextFloat() ÃÑº¢ŒÍÁÙÅàÅ¢·È¹ÔÂÁª¹Ô´ Float ·Ò§á»‡¹¾ÔÁ¾�

nextInt() ÃÑº¢ŒÍÁÙÅàÅ¢¨Ò¹Ç¹àµçÁª¹Ô´ Int ·Ò§á»‡¹¾ÔÁ¾�

nextLine() ÃÑº¢ŒÍÁÙÅáººÊµÃÔ§·Ò§á»‡¹¾ÔÁ¾�

nextLong() ÃÑº¢ŒÍÁÙÅµÑÇàÅ¢ª¹Ô´ Long ·Ò§á»‡¹¾ÔÁ¾�

nextShort() ÃÑº¢ŒÍÁÙÅµÑÇàÅ¢ª¹Ô´ Short ·Ò§á»‡¹¾ÔÁ¾�

àÁ¸Í´áÊ´§¼Å·Ò§¨ÍÀÒ¾¾×é¹°Ò¹

ã¹ÀÒÉÒ¨ÒÇÒ¨ÐãªŒàÁ¸Í´ print áÅÐ println ã¹¡ÒÃáÊ´§¼Å·Ò§¨ÍÀÒ¾ â´Â¨ÐÍÂÙ‹ã¹ÍÍºà¨ç¡µ� out «Öè§ÍÂÙ‹ã¹¤ÅÒÊ System ÃÙ»áºº¡ÒÃãªŒ§Ò¹àÁ¸Í´·Ñé§ÊÍ§¤×Í

System.out.print(data); System.out.println(data); â´Â data à»š¹¢ŒÍÁÙÅ·ÕèµŒÍ§¡ÒÃáÊ´§¼Å ¡ÒÃãªŒ print ËÅÑ§¨ÒáÊ´§¼Å

áÅŒÇ¨ÐäÁ‹¢Öé¹ºÃÃ·Ñ´ãËÁ‹ Ê‹Ç¹ println ¨Ð¢Öé¹ºÃÃ·Ñ´ãËÁ‹ ã¹¡ÒÃáÊ´§¼Å´ŒÇÂàÁ¸Í´ print ËÃ×Í println ¹Ñé¹ÊÒÁÒÃ¶ãªŒ escape sequence ÊíÒËÃÑº¤Çº¤ØÁ¡ÒÃáÊ´§¼Åä´Œ´Ñ§µ‹Íä»¹Õé

Escape sequence ÊíÒËÃÑºàÁ¸Í´áÊ´§¼Å·Ò§¨ÍÀÒ¾¾×é¹°Ò¹

escape sequence ª×èÍ ¤ÇÒÁËÁÒÂ

\n Newline ¢Öé¹ºÃÃ·Ñ´ãËÁ‹

\t Horizontal tab á·çºá¹Ç¹Í¹

\b Backspace ¶ÍÂËÅÑ§ 1 ª‹Í§µÑÇÍÑ¡ÉÃ

\r Return àÅ×èÍ¹à¤ÍÃ�à«ÍÃ�ä»«ŒÒÂÊØ´

\\ Backslash µÑÇÍÑ¡ÉÃ \

\’ Single quote µÑÇÍÑ¡ÉÃ ’

\” Double quote µÑÇÍÑ¡ÉÃ “

ª¹Ô´¢Í§¢ŒÍÁÙÅ µÑÇá»ÃáÅÐ¤‹Ò¤§·Õè

ª¹Ô´¢Í§¢ŒÍÁÙÅ µÑÇá»ÃáÅÐ¤‹Ò¤§·Õè ã¹ÀÒÉÒ¨ÒÇÒáº‹§¢ŒÍÁÙÅÍÍ¡à»š¹ÊÍ§»ÃÐàÀ·ãËÞ‹æ ¤×Í 1. ¢ŒÍÁÙÅáºº¾×é¹°Ò¹ 2. ¢ŒÍÁÙÅáººÍŒÒ§ÍÔ§ «Öè§¨Ðáµ¡µ‹Ò§¡Ñ¹µÃ§¡ÒÃÍŒÒ§¶Ö§µíÒáË¹‹§Ë¹‹ÇÂ¤ÇÒÁ¨íÒ «Öè§¢ŒÍÁÙÅáººÍŒÒ§ÍÔ§¨ÐÍÂÙ‹

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ÁÕ 2 ¤‹Ò ¤×Í true(¨ÃÔ§) ¡Ñº false(à·ç¨)

¢ŒÍÁÙÅáººµÑÇÍÑ¡¢ÃÐ

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ÁÕ 4 »ÃÐàÀ· ¤×Í byte, short, int áÅÐ long «Öè§µ‹Ò§¡Ñ¹µÃ§¢¹Ò´Ë¹‹ÇÂ¤ÇÒÁ¨Ò·ÕèãªŒà¡çº àÁ×èÍ»ÃÐ¡ÒÈµÑÇá»ÃáÅŒÇÊÒÁÒÃ¶¡íÒË¹´¤‹ÒãËŒµÑÇá»Ãä Œàª‹¹¡Ñ¹ áµ‹¶ŒÒµÑÇá»Ãà»š¹ª¹Ô´ long ¨ÐµŒÍ§ãÊ‹ l ËÃ×Í L µÒÁËÅÑ§ áÅÐÂÑ§ÊÒÁÒÃ¶¡íÒË¹´à»š¹àÅ¢°Ò¹ÊÔºË¡â´ÂãªŒ 0x ¹ÒË¹ŒÒµÑÇàÅ¢ä Œ ŒÇÂ ¢ŒÍÁÙÅª¹Ô´àÅ¢·È¹ÔÂÁ

ÁÕ 2 ª¹Ô´ ¤×Í float ¡Ñº double â´Â float ¨ÐãªŒË¹‹ÇÂ¤ÇÒÁ¨Ò 32 ºÔµ Ê‹Ç¹ double ¨ÐãªŒ 64 ºÔµ¶ŒÒ¨Ð

¡íÒË¹´ãËŒ¢ŒÍÁÙÅà»š¹ float ¨ÐµŒÍ§ÁÕ f ËÃ×Í F µÒÁËÅÑ§


»ÃÐàÀ·¢ŒÍÁÙÅ ¢¹Ò´ ª‹Ç§¡ÒÃà¡çº¢ŒÍÁÙÅ boolean 1 ºÔµ à¡çº true ËÃ×Í false

char 2 äºµ� à¡çºÃËÑÊÍÑ¡¢ÃÐáºº Unicode

byte 1 äºµ� -128 ¶Ö§ +127

short 2 äºµ� -32,768 ¶Ö§ +32,767

int 4 äºµ� -2,147,483,648 ¶Ö§ +2,147,483,647

long 8 äºµ� -263 ¶Ö§ +263 - 1

float 4 äºµ� +-3.4 x 10-38 ¶Ö§ +-3.4 x 10+38

double 8 äºµ� +- 1.7 x 10-308 ¶Ö§ +- 1.7 x 10+308


¡ÒÃ¡íÒË¹´ª×èÍáÅÐ¤ÕÂ�àÇÔÃ�´ ÁÕ¡®´Ñ§¹Õé 1. ¢Öé¹µŒ¹´ŒÇÂ A – Z , a – z , $ ËÃ×Í _ à·‹Ò¹Ñé¹ 2. µÑÇµ‹ÍÁÒà»š¹àÅ¢ËÃ×ÍµÑÇÍÑ¡¢ÃÐµÒÁ¢ŒÍ 1 ¡çä´Œ 3. µÑÇ¾Ô¾Á�ãËÞ‹áÅÐàÅç¡ÁÕ¤ÇÒÁËÁÒÂµ‹Ò§¡Ñ¹ 4. µŒÍ§äÁ‹ÁÕàÇŒ¹ÇÃÃ¤ÃÐËÇ‹Ò§¡ÒÃµÑé§ª×èÍ 5. µŒÍäÁ‹«éíÒ¡Ñº¤ÕÂ�àÇÔÃ�´·Õè¨ÒÇÒÃÙŒ¨Ñ¡ ¤‹Ò¤§·Õè ãªŒ final »ÃÐ¡ÒÈ¤‹Ò¤§·Õèâ´ÂÁÕÃÙ»áºº´Ñ§¹Õé final ª¹Ô´¢ŒÍÁÙÅ ª×èÍ¤‹Ò¤§·Õè = ¤‹Ò¢Í§¢ŒÍÁÙÅ;

¡ÒÃ íÒà¹Ô¹¡ÒÃ·Ò§¤³ÔµÈÒÊµÃ�

µÑÇ íÒà¹Ô¹¡ÒÃ·Ò§¤³ÔµÈÒÊµÃ�

µÑÇ´íÒà¹Ô¹¡ÒÃ ¤ÇÒÁËÁÒÂ µÑÇÍÂ‹Ò§¹Ô¾¨¹�

+ ºÇ¡ total = const + tax;

- Åº cost = total – tax;

* ¤Ù³ tax = cost * rate;

/ ËÒÃ saleprice = original / 2

% ËÒÃàÍÒàÈÉ ramainder = value % 3;


µÑÇ íÒà¹Ô¹¡ÒÃ·Ò§¤³ÔµÈÒÊµÃ�áººÂ‹Í

ÅíÒ Ñº¤ÇÒÁÊíÒ¤ÑÞ¢Í§à¤Ã×èÍ§ËÁÒÂ 1.() 2.++,-- 3.%,/,* 4.+,- 5.<,>,<=,>= 6.= =,!= 7.&& 8.ll 9.=,+=,-=,*=,/=,%=


ã¹ÀÒÉÒ¨ÒÇÒ »ÃÐâÂ¤ (statement) ¨Ð¨º ŒÇÂà¤Ã×èÍ§ËÁÒÂ ; (semicolon) àÊÁÍ Ñ§¹Ñé¹â»Ãá¡ÃÁÊÒÁÒÃ¶à¢ÕÂ¹ statement ä ŒÁÒ¡¡Ç‹ÒË¹Öè§Êàµ¨àÁç¹µ�ã¹Ë¹Öè§ºÃÃ·Ñ´¢Í§ source code ËÃ×ÍÊÒÁÒÃ¶à¢ÕÂ¹ statement â´ÂÁÕ¤ÇÒÁÂÒÇÁÒ¡¡Ç‹ÒË¹Öè§ºÃÃ·Ñ´¡çÊÒÁÒÃ¶·íÒä Œ

Expression ËÁÒÂ¶Ö§ »ÃÐâÂ¤ã¹ÀÒÉÒ Java ·Õèä ŒÃÑº¡ÒÃÂÍÁÃÑºÇ‹ÒÍÂÙ‹ã¹ÃÙ»áºº·Õèä Œ¡íÒË¹´äÇŒ ¡ÒÃà¢ÕÂ¹ code ãËŒÁÕÃÙ»áºº·ÕèàËÁÒÐÊÁ Í‹Ò¹ä Œ§‹ÒÂ ¨Ð·íÒãËŒ¡ÒÃ¾Ñ²¹Òâ»Ãá¡ÃÁà»š¹ä»ä Œ ŒÇÂ¤ÇÒÁÃÇ´àÃçÇáÅÐ à»š¹·ÕèÂÍÁÃÑºµÒÁÃÐººÊÒ¡Å ÃÙ»áºº·ÕèàËÁÒÐÊÁ¹Ñè¹¤×Í ¡ÒÃÂ‹ÍË¹ŒÒ (indentation) à¾×èÍãËŒ¡ÒÃÍ‹Ò¹·íÒä Œ§‹ÒÂ áÅÐÁÍ§ ÙÊÇÂ§ÒÁ

¡ÒÃà»ÅÕèÂ¹¢Í§¢ŒÍÁÙÅ

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- ¡ÒÃá»Å§¢ŒÍÁÙÅãËŒÁÕ¢¹Ò´ãËÞ‹¢Öé¹

- ¡ÒÃá»Å§¢ŒÍÁÙÅãËŒÁÕ¢¹Ò´àÅç¡Å§

â´Â·ÑèÇä»ÁÑ¡¨Ðà»ÅÕèÂ¹¢ŒÍÁÙÅãËŒÁÕ¢¹Ò´ãËÞ‹¢Öé¹ à¾ÃÒÐ¶ŒÒËÒ¡á»Å§¢ŒÍÁÙÅãËŒÁÕ¢¹Ò´àÅç¡Å§ÍÒ¨·ÒãËŒ¡ÒÃ»ÃÐÁÇÅ¼Å¢ŒÍÁÙÅà¡Ô´¤ÇÒÁàÊÕÂËÒÂä Œ

¡ÒÃá»Å§¢¹Ò´¢ŒÍÁÙÅâ´Â Cast Operator

ã¹ÀÒÉÒ¨ÒÇÒÊÒÁÒÃ¶á»Å§¢ŒÍÁÙÅ¢¹Ò´ãËÞ‹ãËŒÁÕ¢¹Ò´àÅç¡Å§ä Œâ´ÂãªŒ Cast Operator «Öè§¨Ðà¢ÕÂ¹»ÃÐàÀ·¢ŒÍÁÙÅ·ÕèµŒÍ§¡ÒÃá»Å§äÇŒã¹Ç§àÅçº ŒÒ¹Ë¹ŒÒµÑÇá»Ã·ÕèµŒÍ§¡ÒÃ àª‹¹

x = (int)number;

á»Å§¢ŒÍÁÙÅã¹ number ãËŒà»š¹»ÃÐàÀ· int ¡‹Í¹áÅŒÇà¡çºäÇŒã¹µÑÇá»Ã x (x µŒÍ§à»š¹ int ŒÇÂ)

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1. ¶ŒÒµÑÇ¶Ù¡ íÒà¹Ô¹¡ÒÃµÑÇË¹Öè§à»š¹ double µÑÇ¶Ù¡ íÒà¹Ô¹¡ÒÃÍÕ¡µÑÇ¨Ðà»ÅÕèÂ¹à»š¹ double

2. ¶ŒÒµÑÇ¶Ù¡ íÒà¹Ô¹¡ÒÃµÑÇË¹Öè§à»š¹ float µÑÇ¶Ù¡ íÒà¹Ô¹¡ÒÃÍÕ¡µÑÇ·ÕèÁÕ¢¹Ò´àÅç¡¡Ç‹Ò¨Ð¶Ù¡à»ÅÕèÂ¹à»š¹ float

3. ¶ŒÒµÑÇ¶Ù¡ íÒà¹Ô¹¡ÒÃµÑÇË¹Öè§à»š¹àÅ¢¨íÒ¹Ç¹àµçÁ µÑÇ¶Ù¡ íÒà¹Ô¹¡ÒÃÍÕ¡µÑÇà»š¹ long

µÑÇ¶Ù¡´Òà¹Ô¹¡ÒÃÍÕ¡µÑÇ¨Ð¶Ù¡à»ÅÕèÂ¹à»š¹ long

¤ÅÒÊÊµÃÔ§

¡ÒÃÊÃŒÒ§ String

String à»š¹ Class Ë¹Öè§ã¹ Package ¢Í§ÀÒÉÒ¨ÒÇÒª×èÍ java.lang ·íÒ

Ë¹ŒÒ·Õèã¹ ¡ÒÃà¡çº¢ŒÍÁÙÅ·Õèà»š¹ “ªØ´¢Í§µÑÇÍÑ¡ÉÃ” «Öè§»¡µÔª¹Ô´¢Í§¢ŒÍÁÙÅ¢Í§ÀÒÉÒ¨ÒÇÒ¡çÁÕ

ª¹Ô´à»š¹ character áµ‹à¡çº¢ŒÍÁÙÅä´Œà¾ÕÂ§ 1 µÑÇÍÑ¡ÉÃà·‹Ò¹Ñé¹ ´Ñ§¹Ñé¹ ¨Ö§ÅíÒºÒ¡ã¹¡ÒÃ

¹íÒÁÒãªŒ¡Ñº¢ŒÍÁÙÅ·ÕèÁÒ¡¡Ç‹Ò 1 µÑÇÍÑ¡ÉÃ ËÃ×Í·ÕàÃÕÂ¡Ç‹Ò “String” ´Ñ§¹Ñé¹ ÀÒÉÒ¨ÒÇÒ

¨Ö§ä´ŒÊÃŒÒ§ Class ÊíÒàÃç¨ÃÙ»ÁÒãËŒÊÒÁÒÃ¶àÃÕÂ¡ãªŒä´Œ·Ñ¹·Õ àÃÕÂ¡Ç‹Ò “String” ·Ñé§ËÁ´

¤×Í·ÕèÁÒ¢Í§¤íÒÇ‹Ò String Class

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àÃÒÊÒÁÒÃ¶àÃÕÂ¡ãªŒàÁ¸Í´ä Œâ´ÂàÃÕÂ¡µÑÇá»ÃÍŒÒ§ÍÔ§¢Öé¹µÒÁ ŒÇÂà¤Ã×èÍ§ËÁÒÂ¨Ø´áÅÐµÒÁ ŒÇÂàÁ¸Í´ «Öè§ÁÕÃÙ»áºº Ñ§¹Õé

µÑÇá»Ã.àÁ¸Í´(ÍÒ¡ÔÇàÁ¹µ�)

¡ÒÃãªŒ import

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à¾×èÍºÍ¡ãËŒ¤ÍÁä¾àÅÍÃ�ÃÙŒÇ‹Ò¨Ð¹íÒ¤ÅÒÊÁÒ¨Ò¡·Õèã´ â´Âà¢ÕÂ¹¤íÒÊÑè§ import äÇŒ·ÕèÊ‹Ç¹ËÑÇ¢Í§â»Ãá¡ÃÁ àª‹¹¡ÒÃãªŒ§Ò¹¤ÅÒÊ Scanner ¨ÐµŒÍ§à¢ÕÂ¹ Ñ§¹Õé

import java.util.Scanner

à»š¹¡ÒÃàÃÕÂ¡ãªŒ¤ÅÒÊ Scanner ·Õèà¡çºÍÂÙ‹ã¹ util â´Â util ¹Õéà¡çºÍÂÙ‹ã¹á¾ç¡à¡¨ËÅÑ¡ª×èÍ java

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