Android：HttpUrlConnection变量发布问题

Am sending variables using HttpURLConnection from android to .php file in server. I have strange issue and i don't know how to solve it.

This way works:

for(int i=1; i<parameters.length; i++) {
    postDataParams.put("userInfo" , parameters[i]);    
}

$userInfo=$_POST['userInfo'];

But I need to post as many variables as I have and its not working:

for(int i=1; i<parameters.length; i++) {
    postDataParams.put("userInfo"+i , parameters[i]);
}

$userInfo=$_POST['userInfo1'];