doInBackground(String... params)
// params represents a vararg.
new AsyncHttpPost().execute(s1,s2,s3); // pass strings to doInbackground
params[0] is the first string
params[1] is the second string
params[2] is the third string
http://developer.android.com/reference/android/os/AsyncTask.html#doInBackground(Params...)
The parameters of the asynchronous task are passed to doInBackground