private static Scanner input = new Scanner(new InputStreamReader(socket.getInputStream()));

private static void getAnswer() throws IOException {
    System.out.println("<server> getting answer");
    while (input.hasNextLine()) {
        String line = input.nextLine();
        System.out.println(line);
        request.add(line);
        if (line == null || line.length() == 0) {
            break;
        }
    }
    System.out.println("exit");
}

<server> getting answer
POST /forms/formPOST.html HTTP/1.1
Host: localhost
Connection: keep-alive
Content-Length: 113
Cache-Control: max-age=0
Origin: http://localhost
Upgrade-Insecure-Requests: 1
Content-Type: application/x-www-form-urlencoded
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.140 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8
Referer: http://localhost/forms/formPOST.html
Accept-Encoding: gzip, deflate, br
Accept-Language: ru-RU,ru;q=0.9,en-US;q=0.8,en;q=0.7