title: Listener refused the connection with the following error: ORA-12514
body: <p>I am trying to connect to an Oracle Database using java and JDBC code. I can't do that because I get the error below:</p>
  
  <blockquote>
    <p>java.sql.SQLException: Listener refused the connection with the
    following error: ORA-12514, TNS:listener does not currently know of
    service requested in connect descriptor</p>
  </blockquote>
  
  <p>What is the reason for the error and how to fix it ?</p>
  
  <p>PS- 
  Out of all the DBMS, Oracle express 11g seems to be the most complicated and difficult to use.
  Is that really the case ?</p>