IO Error: The Network Adapter could not establish the connection

I am new to Oracle, and am trying to run a simple example code with Java, but am getting this error when executing the code.. I am able to start up the listener via CMD and am also able to run SQL Plus. Can anyone give me a hand and tell me what I might be doing wrong?

Update: I am using JDBC.

Database is local, and I actually had it working but it stopped working just today. I'm not really sure why though. Would you mind giving me some procedures to follow by since I don't know much.

Solution 1:

Either:

1. The database isn't running
2. You got the URL wrong
3. There is a firewall in the way.

(This strange error message is produced by Oracle's JDBC driver when it can't connect to the database server. 'Network adapter' appears to refer to some component of their code, which isn't very useful. Real network adapters (NICs) don't establish connections at all: TCP protocol stacks do that. It would have been a lot more useful if they had just let the original ConnectException be thrown, or at least used its error message and let it appear in the stack trace.)

Solution 2:

I had the same problem, and this is how I fixed it. I was using the wrong port for my connection.

private final String DB_URL  = "jdbc:oracle:thin:@localhost:1521:orcll"; // 1521 my wrong port

• go to your localhost

• (my localhost address) : https://localhost:1158/em

• login

  • user name
  • password
  • connect as --> normal

• Below 'General' click on LISTENER_localhost

• look at you port number
  • Net Address (ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1522)) Connect to port 1522

• Edit you connection change port 1521 to 1522.

  • done

Solution 3:

Another thing you might want to check that the listener.ora file matches the way you are trying to connect to the DB. If you were connecting via a localhost reference and your listener.ora file got changed from:

HOST = localhost

to

HOST = 192.168.XX.XX

then this can cause the error that you had unless you update your hosts file to accommodate for this. Someone might have made this change to allow for remote connections to the DB from other machines.