how i can connect two remote computers database using server

it simple you can access two or many more remote SQL server system connection.
first you have to enable the sharing of sql server on remote computer and turn off their fire wall.
when your are creating connection string in java you have to define the IP address of that remote system. in case your IPCONFIG its simple.

For Example:
                                10.1.240.44\SQLEXPRESS
please check my article

http://www.c-sharpcorner.com/UploadFile/e881fb/secured-connection-between-sql-server-and-C-Sharp-using-specific/
and please inform me if you have any problem.