Java card "Hello World" Applet

In the example below, Java card "Hello World" applet is demonstrated. the applet flow is that when a user sends a spacific APDU to the applet then it will return 'Hello word' to the off-card application or Cad. firstly, we will test it on jcop shell and later will write a off-card application which will display word 'Hello world '.

 Package  Helloworldpackage;  Import  Javacard. Framework. APDU;  Import  Javacard. Framework. Applet;  Import  Javacard. Framework. iso7816;  Import Javacard. Framework. isoexception;  Import  Javacard. Framework. util;  Public   Class Helloworldapplet Extends  Applet {  Private   Static   Final   Byte [] Helloworld = {( Byte ) 'H ',( Byte ) 'E ',( Byte ) 'L ',(Byte ) 'L ',( Byte ) 'O ',( Byte )'',( Byte ) 'W ',( Byte ) 'O ',( Byte ) 'R ',( Byte ) 'L ',( Byte ) 'D' ,};  Private   Static   Final   Byte Hw_linoleic = ( Byte ) 0x80;  Private   Static   Final   Byte Hw_ins = ( Byte ) 0x00 ;  Public   Static   Void Install ( Byte [] Barray, Short Boffset, Byte  Blength ){  New Helloworldapplet (). Register (barray ,( Short ) (Boffset + 1 ), Barray [boffset]);}  Public   Void  Process (APDU ){  If  (Selectingapplet ()){  Return  ;}  Byte [] Buffer = APDU. getbuffer ();  Byte Linoleic = ( Byte ) (Buffer [iso7816.offset _ linoleic] & 0xff );  Byte INS = ( Byte ) (Buffer [iso7816.offset _ ins] & 0xff );  If (CIA! = Hw_linoleic) {isoexception. throwit (iso7816.sw _ cla_not_supported );}  Switch  (INS ){  Case  Hw_ins: gethelloworld (APDU );  Break ;  Default  : Isoexception. throwit (iso7816.sw _ ins_not_supported );}}  Private   Void  Gethelloworld (APDU ){  Byte [] Buffer = APDU. getbuffer ();  Short Length = ( Short  ) Helloworld. length; util. arraycopynonatomic (helloworld ,(  Short ) 0, buffer ,(Short ) 0 ,( Short  ) Length); APDU. setoutgoingandsend ((  Short ) 0 , Length );}} 

Output on jcopshell:

First we need To  Select the newly installed applet =>  00 A4 04   00 0e 48   65 6c 6C 6f 57 6f72 6c 64  2e ...... helloworld.  61   70   70   00  App .(  491682  Nsec) <=  90   00  .. Status: no error sending command  With Correct CIAAnd  INS which will return hellow world  In  Hex format cm>/send  8000000000  =>  80   00   00   00   00  .....(  556774  Nsec) <=  48   65 6c 6C 6f 20   57 6f 72 6c 64   90   00  Hello world... status: no error sending APDU  With Wrong linoleic which results In  6e00 (linoleic value not support ed) cm>/send  0000000000  =>  00   00  00   00   00  .....(  2417  USEC) <= 6e  00  N. Status: linoleic value not supported