Replace your this code
==================================
operatorDetail=null;
operatorList=null;
SessionText = null;
IPText =null;
DurationText=null;
StatusText=null;
NoOfVisit=null;
ButtonText=null;
operatorDetail = result.split(delimiter1);
SessionText = new ArrayList<String>();
IPText = new ArrayList<String>();
DurationText = new ArrayList<String>();
StatusText = new ArrayList<String>();
NoOfVisit = new ArrayList<String>();
ButtonText = new ArrayList<String>();
=====================================
With Following Code
=====================================
operatorDetail=null;
operatorList=null;
SessionText.clear();
IPText.clear();
DurationText.clear();
StatusText.clear();
NoOfVisit.clear();
ButtonText.clear();
operatorDetail = result.split(delimiter1);
=====================================