Re: [rules-users] Problem with "!=" field constraint

Hi, I have a problem with a rule which uses a "!=" field constraint. The following code illustrates the problem. import org.drools.*; import org.drools.compiler.*; import org.drools.rule.Package; import java.io.*; public class DroolsTest { private RuleBase rules; private StatefulSession memory; public DroolsTest(File file) throws Exception { rules =RuleBaseFactory.newRuleBase(); memory=rules.newStatefulSession(); rules.addPackage(loadPackage(file)); } protected Package loadPackage(File file) throws IOException { FileInputStream stream=null; try { stream=new FileInputStream(file); return(loadPackage(stream)); } finally { if (stream!=null) stream.close(); } } protected Package loadPackage(InputStream stream) throws IOException { try { PackageBuilder builder=new PackageBuilder(); builder.addPackageFromDrl(new InputStreamReader(stream)); return(builder.getPackage()); } catch(Exception ex) { throw new IOException(); } } public StatefulSession getSession() { return(memory); } public static void main(String ... args) { try { DroolsTest test=new DroolsTest(new File(args[0])); SpecialString first42 =new SpecialString("42"); SpecialString second42=new SpecialString("42"); test.getSession().insert(new SpecialString("World")); test.getSession().insert(first42); test.getSession().insert(second42); System.out.println("Fact handle: "+test.getSession().getFactHandle(first42)); System.out.println("Fact handle: "+test.getSession().getFactHandle(second42)); System.out.println("Firing rules ..."); test.getSession().fireAllRules(); } catch (Exception ex) { ex.printStackTrace(); } } } I'm inserting three different objects in the working memory of the Drools 4 Engine. Two of the three objects have the same text - "42". When I'm using the following rule package test rule "A test" when x : SpecialString() y : SpecialString(this!=x) then System.out.println(x+"/"+y); end I get the output Fact handle: [fid:2:2:42[SpecialString@fde8da]] Fact handle: [fid:3:3:42[SpecialString@e4d6ef]] Firing rules ... 42[SpecialString@e4d6ef]/World[SpecialString@faa824] World[SpecialString@faa824]/42[SpecialString@e4d6ef] 42[SpecialString@fde8da]/World[SpecialString@faa824] World[SpecialString@faa824]/42[SpecialString@fde8da] which is not what I expect. Why are combinations of x and y with the two "42"-instances not listed, i.e. Why doesn't the output contain 42[SpecialString@e4d6ef]/42[SpecialString@fde8da] 42[SpecialString@fde8da]/42[SpecialString@e4d6ef] The class SpecialString uses the standard equals(...) and hashCode(...) implementation, so these should be based on the object references, not the content: public class SpecialString { private String text; public SpecialString(String text) { this.text=text; } public String getText() { return(text); } @Override public String toString() { return(getText()+"["+super.toString()+"]"); } } Best regards Markus Wissenswertes für Bastler und Hobby Handwerker. BE A BETTER HEIMWERKER! www.yahoo.de/clever _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users