select * from sys.props$ where name like 'NLS%CHARACTERSET';

 import  java.sql.*;

 public   class  NCharTest {

   private   static   final  String USERNAME = "<username>";

   private   static   final  String PASSWORD = "<password>";

   private   static   final  String SERVER = "jdbc:oracle:thin:@<server>:1521:<SERVICE_NAME>";

   public   static   void  main(String args[])
     throws  Exception {
    DriverManager.registerDriver( new  oracle.jdbc.OracleDriver());
    Connection con = DriverManager.getConnection(SERVER, USERNAME, PASSWORD);
    Statement st = con.createStatement();
    PreparedStatement pst;

     try  {
      st.execute("drop table test_nchar");
    }  catch  (SQLException e) {}
    st.execute("create table test_nchar(ndata nvarchar2(32))");

    String stEscape = "ЙЦУКЕ";
    System.out.println("stEscape=" + stEscape);
    pst = con.prepareStatement("insert into test_nchar (ndata) values (?)");
    pst.setString( 1 , stEscape);
    pst.execute();
    ResultSet rs = st.executeQuery("select * from test_nchar");
     while  (rs.next()) {
      System.out.println(rs.getString( 1 ));
    }

    rs.close();
    st.close();
    con.close();
  }
}