HI ALL, I am using drool 4.0.1 in my project. I am facing problem in using generics feature of jdk1.5. My objective is to perform validation on the basis of data type of variable. for storing values of variable i have one Attribute Class it contains getter setter for values of attribute and attributeId which is a string but value of attribute is of deferent type so i am thinking to use generics here. public class Attribute<T> { public String qualifiedName; public T newValue; public T oldValue; public String getQualifiedName() { return qualifiedName; } public void setQualifiedName(String qualifiedName) { this.qualifiedName = qualifiedName; } public T getNewValue() { return (T)newValue; } public void setNewValue(T newValue) { this.newValue = newValue; } public T getOldValue() { return oldValue; } public void setOldValue(T oldValue) { this.oldValue = oldValue; } } my rule for date comparison looks like: //Date Comparison. rule "W250.1 DateComparison" when $dto : DataProvider() Attribute(newValue < "29-Oct-2007") from $dto.getValue("W250.1") then System.out.println ("Error in Date check \t"); end DataProvider class it is responsible to give instance of attribute corresponding to attributeId: public class DataProvider { HashMap<String,Attribute> fieldMap=new HashMap<String, Attribute>(); public DataProvider() { populateMap(); } public Attribute getValue(String qualifiedName){ Attribute attribute = fieldMap.get(qualifiedName); return attribute; } public void populateMap(){ Attribute<Date> attribute = new Attribute<Date>(); SimpleDateFormat format = new SimpleDateFormat("dd-MMM-yyyy"); Date date; try { date = format.parse("27-Oct-2007"); attribute.setQualifiedName("W250.1"); attribute.setOldValue(date); attribute.setNewValue(date); fieldMap.put(attribute.getQualifiedName(),attribute); } catch (ParseException e) { e.printStackTrace(); } } } in this case i am getting exception: Exception in thread "main" java.lang.ClassCastException: java.lang.String when i am not using generics this rule is working fine. but in this case how should i perform validation depending upon data type of attribute. can you please help me in solving this problem. Thanks, Gaurav Joshi -- View this message in context: http://www.nabble.com/Problem-in-using-genrics-with-drools4.0.1.-tf458655... Sent from the drools - user mailing list archive at Nabble.com.