usage consumption by not reading the full response

Hi,
I want to read only part of a httpurlconnection response.

Now I have:

while ((line = reader.readLine()) != null) {
    sb.append(line);
}

I want to have:

while ((line = reader.readLine()) != null && !line.contains("blah") {
    sb.append(line);
}

Meaning, read until the line contains the word blah, then stop. Am I really reading less and improving the data consumption? If not, is there a way to stop reading to decrease consumption or the data is consumed no matter what?

Thanks