Modifiers:
ªð£¶õ£è
class
-¬ù ⿶ñ¢ ªð£¿¶ modifiers âù¢Á ܬöè¢èð¢ð´ñ¢
abstract, public, ñø¢Áñ¢ final ºîô£ù¬õ
ðòù¢ð´î¢îð¢ð´è¤ù¢øù. 覫ö
ªè£´è¢èð¢ð좴÷¢÷
â´î¢¶è¢è£ì¢´è¬÷ èõù¤»é¢è÷¢
abstract class my_graphics
{
....
}
public final class String
{
....
}
abstract âù¢Á ªè£´è¢°ñ¢ ªð£¿¶ Üï¢î class-ù¢ à÷¢ â¿îð¢ð´ñ¢ function
åù¢ªøÂñ¢
abstract
Ýè Þ¼è¢è «õí¢´ñ¢. abstract class åù¢Á Þ¼ð¢ðî£è¾ñ¢
Üî¬ùê¢
ê£ó¢ï¢¶ ðô subclass -è÷¢ Þ¼ð¢ðî£è¾ñ¢
ªè£÷¢Àé¢è÷¢. â´î¢¶è¢
è£ì¢ì£è
my_graphics
âù¢ø class Ýù¶ abstract class Ýè Þ¼è¢è¤ù¢ø¶.
Üî¬ùê¢
ê£ó¢ï¶ circle,
rectangle, triangle ºîô¤ò class-è÷¢ subclass-è÷£è
Þ¼è¢è¤ù¢øù.
Þ¬õ ܬùî¢î¤¼è¢°ñ¢ Draw âù¢ø ªðòó¤ô¢ function-è÷¢
Þ¼è¢è¤ù¢ø¶
âù¢Á ¬õ袪è£í¢ì£ô¢, ܬõ åõ¢ªõ£ù¢Áñ¢ ªõõ¢«õÁ
«õ¬ô
ªêò¢õîø¢°ð¢ ðòù¢ð´ñô¢ôõ£? Þ¶ «ð£ù¢ø êñòé¢è÷¤ô¢ ï£ñ¢ Þõø¢¬ø
abstract º¬øò¤ô¢ â¿î «õí¢´ñ¢.
final âù¢ø modifier Ýù¶ ðòù¢ð´î¢îð¢ðì¢ì£ô¢ Üï¢î class -¬ù inheritance
ªêò¢ò
Þòô£¶. Üî£õ¶ Üï¢î class Ýù¶ «õÁ âï¢î class -ø¢è¢°ñ¢ superclass
Ýè
ªêòô¢ðì Þòô£¶.
public âù¢ø modifier Ýù¶ ðòù¢ð´î¢îð¢ðì¢ì£ô¢ Üï¢î class -¬ù ,
«õÁ
ðô ¹«ó£è¤ó£ñ¢è÷¤ô¢ Þ¼ï¢¶è¢ ðòù¢ð´î¢î¤è¢ ªè£÷¢÷ô£ñ¢.
â´î¢¶è¢è£ì¢ì£è
ï£ñ¢ Java
õ¤ô¢ ðòù¢ð´î¢¶ñ¢ String âù¢Âñ¢ class -¬ù
public class Ýè â¿î¤ Þ¼ð¢ðîù£ô¢ î£ù¢ ïñ¢ñ£ô¢ Üî¬ù ܬù
¹«ó£è¤ó£ñ¢è÷¤½ñ¢
ðòù¢ð´î¢î º®è¤ù¢ø¶.
this ñø¢Áñ¢ super
Java õ¤ô¢ this ñø¢Áñ¢ super âù Þóí¢´ ê¤ø𢹠keyword -è÷¢ Þ¼è¢è¤ù¢øù.
å¼ class -ù¢ à÷¢ ï£ñ¢ ðô¢«õÁ variable -è÷¢ ñø¢Áñ¢ function -è¬÷ â¿î¤
ò¤¼ð¢«ð£ñ¢.
Þõø¢¬ø Üï¢î class -è÷¤ù¢ Object ´è÷¢ õö¤ò£è Þò袰è¤ù¢«ø£ñ¢
Üô¢ôõ£? Üï¢î êñòé¢è÷¤ô¢ åõ¢ªõ£Á Object -ø¢è¢°ñ¢ âù¢Á îù¤î¢îù¤ò£è
variable -è÷¢ ºîô£ù¬õ à¼õ£°ñ¢. âï¢î variable âï¢î object -®Â¬ìò¶
âù¢ðî¬ù
ªê£ô¢õîø¢è¢è£è this âÂñ¢ operator ðòù¢ð´è¤ù¢ø¶.
Listing
2.6
class student
{
int rollno;
String name;
public void store(int rollno, String name)
{
this.rollno = rollno;
this.name = name;
}
public void display()
{
System.out.println(“Roll Number: “ + this.rollno);
System.out.println(“Name: “ + this.name);
System.out.println(“”);
}
public static void main(String arg[])
{
student nancy = new student();
38
student john = new student();
student george = new student();
nancy.store(1,”Nancy Jenifer”);
nancy.display();
john.store(2,”John Thomas”);
john.display();
george.store(3,”George Clinton”);
george.display();
}
}
Þ颰 student âù¢Âñ¢ class ô¢ õ¬óò¼è¢èð¢ð좴÷¢÷ RollNo, Name,
Ýè¤ò variable -è¬÷ Üï¢î class-ù¢ function è÷¤ô¢ this.Rollno, this.name âù¢Á
ðòù¢ð´î¢î¤ò¤¼ð¢ð¬îè¢
èõù¤»é¢è÷¢. Üî£õ¶ Student class -ø¢è¢°, ï£ñ¢ nancy,
john, george âù¢Á Íù¢Á Object -è÷¢
à¼õ£è¢è¤ò¤¼è¢è¤ù¢«ø£ñ¢. Þï¢î Íù¢Á
object -´èÀ袰ñ¢
îù¤î¢îù¤ò£è Rollno, Name ºîô£ù variable-è÷¢ Þ¼ð¢ð¬î
郎ùõ¤ô¢
ªè£÷¢Àé¢è÷¢. ï£ñ¢ nancy.store( ), john.store( ) âù¢Á
õ¬èò¤ô¢
function -è¬÷ àð«ò£è¤è¢°ñ¢ ªð£¿¶, Üï¢î function -è÷¤ô¢ this.rollno, this.name
âù¢Á
ªè£´î¢î¤¼ð¢ðîù¢ Íôñ¢ Üï¢îï¢î object -èÀ袰ø¤ò variable -è÷¢
ðòù¢ð´î¢îð¢ð´è¤ù¢øù.
°ø¤ð¢¹
:
Þ颰 this âù¢ð¶ ðòù¢ð´î¢îðð¢ì£õ¤ì¢ì£½ñ¢ åù¢Áñ¢ ð¤óê¢ê¬ù
Þô¢¬ô.
ãªùù¤ô¢ Ü颰 Þòø¢¬èò£è«õ this operator Þ¼ð¢ðî£è Java
compiler 郎ùî¢¶î¢ ªè£÷¢Àñ¢.
super âù¢ð¶
inheritance
ªêò¢»ñ¢ªð£¿¶ ðòù¢ð´è¤ù¢ø¶. Üî£õ¶
Child class -è÷¤ô¢ ޼ super class -ô¢ Þ¼è¢è¤ù¢ø function -è¬÷
àð«ò£èð¢ð´î¢¶õîø¢°
Þ¶ ðòù¢ð´è¤ù¢ø¶. °ø¤ð¢ð£è å¼ super class ô¢
constructor function Þ¼ð¢ðî£è ªè£÷¢Àé¢è÷¢. ï£ñ¢ child class -ø¢° object -
´è¬÷
à¼õ£è¢°ñ¢ ªð£¿¶ child class -ô¢ Þ¼è¢è¤ù¢ø constructor
function
î£ù¢
Þò颰ñ¢. Ýù£ô¢ inheritance Þ¼ð¢ðîù£ô¢ base class -ù¢ object åù¢Á
î£ù£è
à¼õ£°ñ¢ function
-è÷¤ø¢° ñî¤ð¢¹è¬÷ ªè£´ð¢ðîø¢° super âÂñ¢
º¬øò¤ù£ô¢
ðòù¢ð´î¢î¤è¢ ªè£÷¢÷ô£ñ¢.
Listing
2.7
39
class state
{
String state_name;
state(String tstr)
{
state_name = tstr;
}
public void state_assign(String tstr)
{
state_name = tstr;
}
public void state_display()
{
System.out.println(“State Name : “ + state_name);
}
}
class city extends state
{
String city_name;
city(String tstr)
{
super(“Tamil Nadu”);
city_name = tstr;
}
public void city_assign(String tstr)
{
city_name = tstr;
}
public void city_display()
40
{
System.out.println(“City Name : “ + city_name);
}
}
class country
{
public static void main(String arg[])
{
city chennai = new city(“Chennai”);
chennai.state_display();
chennai.city_display();
}
}
Þï¢îð¢
¹«ó£è¤ó£ñ¤ô¢ state ñø¢Áñ¢ city âù¢Á Þóí¢´ class -è÷¢ Þ¼è¢è¤ù¢øù.
Þóí¢´ñ¢
inheritance
º¬øò¤ô¢ Þ¬íè¢èð¢ð좮¼è¢è¤ù¢ø¶. state âù¢ð¶
superclass
Ýè¾ñ¢
city âù¢ð¶ child class Ýè¾ñ¢ Þ¼è¢è¤ù¢ø¶. Þóí¢´ class è÷¤½«ñ constructor
function â¿îð¢ð좮¼è¢è¤ù¢ø¶. main( ) function -ù¤ô¢ ï£ñ¢ city chennai = new
city (‘chennai’)
âù¢Á
ªè£´î¢¶ chennai
âù¢Á å¼ Object -¬ù city âÂñ¢ class -ô¢ ޼
à¼õ£è¢°è¤ù¢«ø£ñ¢.
ï£ñ¢ parameter
Ýè ªè£´è¢°ñ¢ ‘Chennai’ âù¢ø ñî¤ð¢¹ city class -ù¢
constructor -¼è¢° àó¤ò¶. city class -ù¢ constructor
function -ù¤ô¢ ï£ñ¢ super (‘Tamil nadu’);
âù¢Á
ªè£´î¢î¤¼ð¢ð¬îè¢ èõù¤»é¢è÷¢. Þï¢î èì¢ì¬÷ super class Ýù state ¬ìò
constructor function -ø¢° ñî¤ð¢¹è¬÷è¢
ªè£´è¢è¤ù¢ø¶.
கருத்துகள் இல்லை:
கருத்துரையிடுக
குறிப்பு: இந்த வலைப்பதிவின் உறுப்பினர் மட்டுமே ஒரு கருத்துரையை வெளியிடக்கூடும்.