title: Oracle Jdeveloper - IO Error: The Network Adapter could not establish the connection
body: <p>I'm a rookie with JDeveloper and I'm trying to use JDBC. I create a database project with its database diagram to make offline database but when I tried to create a new database conection and test it this error appears:'IO Error: The Network Adapter could not establish the connection'. </p>
  
  <p>I searched it on google and appeared some things like alter some archives (tnsnames.ora for example) but I can't find them in JDeveloper folder, I also see something about tnsping but I didn't find it either. I tried to reinstall it but it didn't work. My JDeveloper version is: JDeveloper studio edition 12.1.2.0.0 (32bits). </p>
  
  <p>Someone knows how to make it work? What I'm doing wrong? I'll be gratefull with any clue you can lend me. Thank you. </p>