This tip shows a way to obtain the list of all available newsgroup from a news server.

 import sun.net.nntp.*;
import sun.net.*;
import java.io.*;
import java.util.*;

public class ListGroups extends NntpClient {
  public static void main(String[] args) {
    String server = "news";
    try {
      System.out.println("opening server");
      NntpClient nc = new NntpClient(server);
      System.out.println("asking for help");
      nc.serverOutput.println("HELP");
      String theLine = "";
      DataInputStream dis = new DataInputStream(nc.serverInput);
      while ((theLine = dis.readLine()) != null) {
        if (theLine.equals(".")) break;
        System.out.println(theLine);
      }
      nc.askServer("QUIT");
      nc.closeServer();
    }
    catch (IOException e) {
      System.err.println(e);
    }
  }
}