New answer, powershell

TCP

Get-Process -Id (Get-NetTCPConnection -LocalPort YourPortNumberHere).OwningProcess

UDP

Get-Process -Id (Get-NetUDPEndpoint -LocalPort YourPortNumberHere).OwningProcess

Old answer, cmd

 C:\> netstat -a -b

(Add -n to stop it trying to resolve hostnames, which will make it a lot faster.)

Note Dane's recommendation for TCPView. It looks very useful!

-a Displays all connections and listening ports.

-b Displays the executable involved in creating each connection or listening port. In some cases well-known executables host multiple independent components, and in these cases the sequence of components involved in creating the connection or listening port is displayed. In this case the executable name is in [] at the bottom, on top is the component it called, and so forth until TCP/IP was reached. Note that this option can be time-consuming and will fail unless you have sufficient permissions.

-n Displays addresses and port numbers in numerical form.

-o Displays the owning process ID associated with each connection.

If you added it in the control panel while your command prompt was open, that won't affect your current command prompt. You'll need to exit and re-open or simply do:

set "path=%path%;c:\program files\java\jdk1.6.0_16\bin"

By way of checking, execute:

echo %path%

from your command prompt and let us know what it is.

Otherwise, make sure there is a javac in that directory by trying:

"c:\program files\java\jdk1.6.0_16\bin\javac.exe"

from the command prompt. You can also tell which executable (if any) is being used with the command:

for %i in (javac.exe) do @echo %~$PATH:i

This is a neat trick similar to the which and/or whence commands in some UNIX-type operating systems.