title: "Illegal State Exception: Already Connected" when using HttpURLConnection
body: <p>I get an illegal state exception when i set DoOutput to true.</p>
  
  <pre><code>public boolean sendLinksToMaster(String ipport, List&lt;String&gt; links){
  
          boolean sent = false;
          String[] tokens = ipport.split(":");    
          String data = edu.cis555.searchengine.utils.Utils.generateLinks(links);
          HttpURLConnection conn=null;
          try{
              String encodedData = URLEncoder.encode(data, "UTF-8");
          try{
  
                  String ip =tokens[0];
                  String port = tokens[1];
                  String path = edu.cis555.searchengine.utils.Constants.URL_ADD_LINK;
                  System.setProperty("http.keepAlive", "false");
                  URL u = new URL("http", ip, Integer.parseInt(port),"/"+path);
  
                  conn = (HttpURLConnection)u.openConnection();
                  //ERROR IN THIS LINE
                  conn.setDoOutput(true);
                  conn.setRequestMethod("POST");
                  OutputStream stream = conn.getOutputStream();
                  stream.write(encodedData.getBytes());
                  stream.close();
  
                  if(conn.getResponseCode() == HttpURLConnection.HTTP_OK)
                      sent=true;
  
              //  LOG.debug(conn.getResponseCode());
                  conn.disconnect();
              }catch(MalformedURLException mfe){
                  LOG.debug(mfe.getMessage());
                  if(conn!=null){
                      conn.disconnect();
                  }
              }catch(IOException ioe){
                  LOG.debug(ioe.getMessage());
                  if(conn!=null){
                      conn.disconnect();
                  }
              }
  
          }catch(Exception e){
              LOG.debug(e.getMessage());
              if(conn!=null){
                  conn.disconnect();
              }
          }
          return sent;
  
      }
  </code></pre>
  
  <p>The stack trace displayed for the same is:</p>
  
  <pre><code>java.lang.IllegalStateException: Already connected
  at java.net.URLConnection.setDoOutput(Unknown Source)
  at edu.upenn.cis455.xpathengine.utils.pool.ThreadPool.sendLinksToMaster(ThreadPool.java:357)
  at edu.upenn.cis455.xpathengine.utils.pool.ThreadPool$Worker.processAndAddToQueue(ThreadPool.java:314)
  at edu.upenn.cis455.xpathengine.utils.pool.ThreadPool$Worker.run(ThreadPool.java:269)
  at java.lang.Thread.run(Unknown Source)
  </code></pre>
  
  <p>I don't see anything I am doing wrong with sending the request. Could anyone point out what is missing or what am I doing wrong</p>