Java card does not support string and char types. if you want to send string/chars for example 'Hello World' to the card and store them then you need to convert them into hex format and then send the converted hex string to the card.
The command APDU will be then,
CLA --- Your class byte, can be 80
INS --- Your Ins byte, can be 01
P1 --- Parameter P1 can be 00
P2 --- Parameter P2 can be 00
LC --- Length of Hello World hex string (0B)
Data --- Hellow World Hex String (48656c6c6f20576f726c64)
Le -- 00
Thanks for your help it was verry useful
i am a beginer and i didn t found a lot of document in javacard .
I have two questions ?
there is a way to create file on a javacard ? if yes how ?
the second , my card was coming with a biometrical terminal , how can use that , just a simple code in the way to authentifiate and to compare my fingerprint ?