private void sendRequest(BlockPdu pdu) {
   setButton.setEnabled(false);
   getButton.setEnabled(false);
   getNextButton.setEnabled(false);
   lmessage.setText("Sending request ..");
   lmessage.setBackground(Color.white);
   try {
     varbind var = pdu.getResponseVariableBinding();
     AsnObjectId oid = var.getOid();
     AsnObject res = var.getValue();
     if (res != null) {
       toid.setText(oid.toString());
       tvalue.setText(res.toString());
       lmessage.setText("Received aswer ");
       lmessage.setBackground(Color.white);
     } else {
       lmessage.setText("Received no aswer ");
       lmessage.setBackground(Color.red);
     }
   } catch (PduException exc) {
     lmessage.setText("PduException: " + exc.getMessage());
     lmessage.setBackground(Color.red);
     exc.printStackTrace();
   } catch (java.io.IOException exc) {
     lmessage.setText("IOException: " + exc.getMessage());
     lmessage.setBackground(Color.red);
     exc.printStackTrace();
   }
   setButton.setEnabled(true);
   getButton.setEnabled(true);
   getNextButton.setEnabled(true);
 }
  public void actionPerformed(ActionEvent evt) {
    Object src = evt.getSource();

    try {
      if (src == propDialog) {
        propDialog_actionPerformed(evt);
      } else {
        pdu = new BlockPdu(context);
        if (src == setButton) {
          pdu.setPduType(BlockPdu.SET);
          pdu.addOid(toid.getText(), new AsnOctets(tvalue.getText()));
        } else if (src == getButton) {
          pdu.setPduType(BlockPdu.GET);
          pdu.addOid(toid.getText());
        } else if (src == getNextButton) {
          pdu.setPduType(BlockPdu.GETNEXT);
          pdu.addOid(toid.getText());
        }
        sendRequest(pdu);
      }
    } catch (Exception exc) {
      exc.printStackTrace();
      lmessage.setText("Exception: " + exc.getMessage());
      lmessage.setBackground(Color.red);
    }
  }
 void propDialog_actionPerformed(ActionEvent evt) {
   String cmd = evt.getActionCommand();
   if (cmd.equals("Cancel") == false) {
     createContext(
         propDialog.getHost(),
         propDialog.getPort(),
         propDialog.getCommunityName(),
         propDialog.getSocketType());
     sendGetRequest(toid.getText());
   } else {
     // System.exit(0);
   }
 }
  public void init() {
    try {
      createPropertyDialog();
      jbInit();

      propDialog.setVisible(true);
      propDialog.toFront();

      createContext(
          propDialog.getHost(),
          propDialog.getPort(),
          propDialog.getCommunityName(),
          propDialog.getSocketType());
      sendGetRequest(toid.getText());
    } catch (Exception exc) {
      exc.printStackTrace();
      lmessage.setText("Exception: " + exc.getMessage());
      lmessage.setBackground(Color.red);
    }
  }