问题
I am new to Programming. I am learning JAVA and for DB i wanted to learn Oracle so I downloaded sqldeveloper from Oracle website. It was a zip file so I didnot have to install anything, simply extracted it. When I open the sqldeveloper and try to make a new connection, it shows error.
Test failed: IO Error: The network adapter could not establish the connection.
I am not sure what to put in username and pwd. and i am also not sure if i have to connect this to jdk or jre or set classpath for database.
Can anyone help me?? I have uploaded the snapshot of the error too.
回答1:
You downloaded a client.
You did NOT download the server component though - the actual database.
SQL Developer just allows you to work with an existing database.
No worries, you're not that far away. You have several options.
Oracle Database Express Edition (XE) - it's completely free.
We also have a VirtualBox appliance you can use for personal learning purposes, also completely free.
I talk about this and give step by step instructions here.
回答2:
Check if oracle service, TNSListener service is up and running before trying to make any new connection from sql developer.
Even if TNS Service is down , connection can not be established with oracle instance.
来源：https://stackoverflow.com/questions/42018978/cannot-create-a-new-connection-is-sqldeveloepr