java - JDBC Connection from Android to Oracle

Question

I am trying to connect from Android application (2.2 - 4.3) to Oracle XE 10 with JDBC driver. I am using Eclipse and I added JDBC jar file to "libs" folder so It´s automatically in "Android private libraries". But after I run application in emulator it still throws ClassNotFoundException - oracle.jdbc.OracleDriver.

I have now only short testing code similar to this: https://stackoverflow.com/a/15756421/2922469, but for Oracle of course.

I searched in many answers here, but nothing help me to solve this problem. Could anyone help me please?

edit: I first tried classes12.jar, but there was some errors, so I added ojdbc6.jar downloaded directly from Oracle website.

TextView tv = (TextView)this.findViewById(R.id.textView3);

    try {
        Class.forName("oracle.jdbc.driver.OracleDriver");  
        Connection con = DriverManager.getConnection(url, user, pass);

        String result = "Database connection success\n";
        Statement st = con.createStatement();
        ResultSet rs = st.executeQuery("select * from knihy");
        ResultSetMetaData rsmd = rs.getMetaData();

        while(rs.next()) {
            result += rsmd.getColumnName(1) + ": " + rs.getInt(1) + "\n";
            result += rsmd.getColumnName(2) + ": " + rs.getString(2) + "\n";
        }
        tv.setText(result);
    }
    catch(Exception e) {
        e.printStackTrace();
        tv.setText(e.toString());
    }