UPDATE
as answer below shows that is error couse by JDBC so is there any other suggestion to migrate access database to oracle database other than using toad and the hard way to do it because trigger views sequences wont be imported by that way so I have to create them by my self??! :S
I am migrating database from access 2003
to oracle database 12c
but Arabic characters are shown as question marks at the step where you connect to access database using SQL developers
I followed what you suggest at this answer and restart my pc but nothing changed
NOTE
when opening .mdb file
from access Arabic characters shown right but when opening it from SQL developers
I get question marks instead of arabic characters
is there anything else to do ?
I run that query as @krokodilko suggested and I get below result
select * from nls_database_parameters where parameter like '%CHAR%'
NLS_NCHAR_CONV_EXCP FALSE
NLS_NUMERIC_CHARACTERS .,
NLS_NCHAR_CHARACTERSET AL16UTF16
NLS_CHARACTERSET AR8MSWIN1256
select * from nls_session_parameters where parameter like '%LANG%';
NLS_LANGUAGE ENGLISH
NLS_DATE_LANGUAGE ENGLISH
by the way when I open another Oracle schema Arabic characters show correctly dose access has special encoding ?