java - How it comes that URL.openConnection() allows me to read header? -

i experimenting java networking , found bit odd thing, suppose have

url url = new url("http://www.google.com"); urlconnection con = url.openconnection(); 

then can call methods, con.getcontentlength() , on , give me correct values, despite didn't envoke con.connect(). how can be? mean, from/how urlconnection gets headers, didn't invoke con.connect() yet, no requests sent , no headers should available @ moment.

the actual tcp connect happens implicitly when call method requires response, such getcontentlength(), getinputstream(), getresponsecode(). doesn't happen @ openconnection(). request sent @ point.

unless using 1 of streaming modes , you're doing put or post request content, in case connection opened when start writing request.