There has to be something I do not understand about using rules. Take this simple class and rules and I don't understand the output. First, when the rule constructor is executed it appears as though only the value 1 was put into the map, then it runs rule test1 and then it sees only values 2 and 3. Secondly, look at rule test2 right now the RHS displays true, BUT if you comment out the eval(true) and uncomment either of the evals you get a nullpointer at runtime. I do not understand why there is a null pointer. Any insight would be wonderful, I have been banging my head against this for a bit and it's probably something stupid. Thanks! --------------------------------- package test.map; import java.util.HashMap; import java.util.Map; public class Test { public Test() { values = new HashMap<String, Object>(); } private Map<String, Object> values; public Map<String, Object> getValues() { return values; } public void setValues(Map<String, Object> values) { this.values = values; } } ----------------------------------------- package test.map import java.math.BigDecimal; import java.util.Map; rule "Constructor" no-loop true when eval(true); $t : Test(values:values) then drools.setFocus("test2"); drools.setFocus("test1"); values.put("one", new BigDecimal("1")); addValue($t, "two", new BigDecimal("2")); $t.getValues().put("three", new BigDecimal("3")); update($t); System.out.println("in constructor"); System.out.println(values); System.out.println(); end rule "test1" no-loop true agenda-group "test1" when eval(true); $t : Test(values:values) then System.out.println("in test1"); System.out.println(values); System.out.println(); end rule "test2" no-loop true agenda-group "test2" when eval(true); $t : Test(values:values) //eval(((BigDecimal)values.get("two")).equals(new BigDecimal("2"))); //eval(((BigDecimal)$t.getValues().get("two")).equals(new BigDecimal("2"))); then System.out.println(((BigDecimal)$t.getValues().get("two")).equals(new BigDecimal("2"))); end function void addValue(Test t, String key, BigDecimal value) { t.getValues().put(key, value); } --------------------------------------- This is a simple class to start it up. --------------------------------------- package test.map; import java.io.InputStreamReader; import java.io.Reader; import org.drools.RuleBase; import org.drools.RuleBaseFactory; import org.drools.WorkingMemory; import org.drools.compiler.PackageBuilder; import org.drools.rule.Package; public class Mainclass { public static void main(String[] args) { try { //load up the rulebase RuleBase ruleBase = readRule(); WorkingMemory workingMemory = ruleBase.newStatefulSession(); Test test = new Test(); workingMemory.insert(test); workingMemory.fireAllRules(); } catch (Throwable t) { t.printStackTrace(); } } /** * Please note that this is the "low level" rule assembly API. */ private static RuleBase readRule() throws Exception { Reader source = new InputStreamReader(Mainclass.class.getResourceAsStream("/Nulltest.drl")); System.setProperty("drools.compiler", "JANINO"); PackageBuilder builder = new PackageBuilder(); builder.addPackageFromDrl( source ); Package pkg = builder.getPackage(); RuleBase ruleBase = RuleBaseFactory.newRuleBase(); ruleBase.addPackage( pkg ); return ruleBase; } } Jeff Shutt Software Developer SOS Staffing Services (801) 924-0429 shuttj(a)sosstaffing.com