Java NullPointerException in Java Agent

Question

I'm developing a java agent. I have an NullPointerException error which I do believe should not happen.

Here is the debug console message:

java.lang.NullPointerException
    at sun.net.www.http.HttpClient.parseHTTPHeader(HttpClient.java:719)
    at sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:646)
    at COM.ibm.JEmpower.applet.http.HttpURLConnection.getInputStream(HttpURLConnection.java:411)
    at COM.ibm.JEmpower.applet.http.HttpURLConnection.getHeaderField(HttpURLConnection.java:703)
    at java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:399)
    at JavaAgent.NotesMain(JavaAgent.java:16)
    at lotus.domino.AgentBase.runNotes(Unknown Source)
    at lotus.domino.NotesThread.run(Unknown Source)

This the code in the java agent

import lotus.domino.*;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Date;
public class JavaAgent extends AgentBase {

    public void NotesMain() {
      String strAux = "[A Working URL]";
      try {
          Session session = getSession();
          AgentContext agentContext = session.getAgentContext();

          // (Your code goes here)

          HttpURLConnection httpCon = (HttpURLConnection) new URL(strAux).openConnection();

          httpCon.setRequestMethod("HEAD");
          httpCon.setConnectTimeout(20000);  
          httpCon.setReadTimeout(20000);

          httpCon.connect();

          System.out.println(HttpCon.getURL().toString());

          int responsecode = httpCon.getResponseCode();
          System.out.println("Response code is " + responsecode + " - " + httpCon.getResponseMessage());
      } catch(Exception e) {
          e.printStackTrace();
      }
    }

}

Basically the error points to System.out.println("Response code is " + httpCon.getResponseCode() + " - " + httpCon.getResponseMessage());.

The thing is that the URL is a working link since I've tried it by accessing in a browser.

What could be the possible reasons for this error? It doesn't work as well on a local notes db that I created for testing. However, in a normal java program not developed in notes, it works.

Answer 1

It's pointless getting the response code before you've sent anything. You're supposed to send the request first, then get the response code, then get the response if required