cannot load drools rule, getting error: unable to resolve object type

Question

i'm new to drools, i'm trying to run the hello world but it keeps giving me this error

Some errors exists in packageBuilder Unable to resolve ObjectType 'Messagee' : [Rule name='Hello World']

Exception in thread "main" java.lang.IllegalArgumentException: Could
not parse knowledge.
at hellodrools.HelloWorldRuleTest.initialiseDrools(HelloWorldRuleTest.java:55)
at hellodrools.HelloWorldRuleTest.main(HelloWorldRuleTest.java:26)

Rule Compilation error : [Rule name='Hello World'] hellodrools/Message/Rule_Hello_World720710180.java (1:8) : The package hellodrools.Message collides with a type

my drl file:

package hellodrools.Message
rule 'Hello World'
when
message:Message (type == 'Hello')
then
message.printMessage();
end

Message.java

package hellodrools;

public class Message{

    private String type;

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public void printMessage() {
        System.out.println("Type: " + type);
    }
}

HelloWorldTestRule.java

package hellodrools;

import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.drools.core.RuleBase;
import org.drools.core.RuleBaseFactory;
import org.drools.core.StatefulSession;
import org.drools.compiler.compiler.DroolsParserException;
import org.drools.compiler.compiler.PackageBuilder;
import org.drools.compiler.compiler.PackageBuilderErrors;
import hellodrools.Message;


public class HelloWorldRuleTest {
    private static RuleBase rbase = RuleBaseFactory.newRuleBase();;
    private static PackageBuilder pbuilder = new PackageBuilder();
    private static StatefulSession sessionObject;
    private static String DRL_FILE = "/helloWorld.drl";



    public static void main(String[] args) {
        initialiseDrools();
        initiliseMessageObject();
        runRules();
    }

    // Method to initialise the package builder and add package to the rule
    // base.
    private static void initialiseDrools() {
        // 1. Read the DRL File and add to package builder
        try {
            Reader reader = new InputStreamReader(
                    HelloWorldRuleTest.class.getResourceAsStream(DRL_FILE));
            pbuilder.addPackageFromDrl(reader);
        } catch (DroolsParserException ex) {
            Logger.getLogger(HelloWorldRuleTest.class.getName()).log(
                    Level.SEVERE, null, ex);
        } catch (IOException ex) {
            Logger.getLogger(HelloWorldRuleTest.class.getName()).log(
                    Level.SEVERE, null, ex);
        }

        // 2. Check for any errors
        PackageBuilderErrors errors = pbuilder.getErrors();

        if (errors.getErrors().length > 0) {
            System.out.println("Some errors exists in packageBuilder");
            for (int i = 0; i < errors.getErrors().length; i++) {
                System.out.println(errors.getErrors()[i]);
            }
            throw new IllegalArgumentException("Could not parse knowledge.");
        }

        // 3. Add package to rule base
        try {
            rbase.addPackage(pbuilder.getPackage());
        } catch (Exception e) {
            System.out.println("Error: " + e);
        }
    }

    // Method to insert message object in session
    private static void initiliseMessageObject() {
        Message msg = new Message();
        msg.setType("Hello");
        sessionObject = rbase.newStatefulSession();
        sessionObject.insert(msg);
    }

    // Method to fire all rules
    private static void runRules() {
        sessionObject.fireAllRules();
    }
}

Solution

Try changing package hellodrools.Message to package hellodrools

Or

modify message:Message (type == 'Hello') to message:hellodrools.Message (type == 'Hello')