Android :: Query About The Usage Of HttpsURLConnection

I am using HttpsURLConnection to post data to a web server.

Here is the function I wrote to get the result. (see the code below)

Very strangely, when the function be first called in my program it would very likely return -1; and then I re-call the function after the first call, it would always work ok.

So I wonder if there is anything I am missing in the code that when the function be firstly called, the missing party is be "initialized", in that the followed call goes OK.

Here is my code of the function:

CODE:....................