Drools 5/ Java 8 compatibility

[Karun Nadarajah]

I had difficulty finding info about how to make Drools 5 work with Java 8, so I am posting this info here in case it helps anyone.  You do not need to upgrade to Drools 6 to work with Java 8.  If you ensure the eclipse compiler jar you have imported is version 4.3.1 or higher (ecj-4.3.1.jar), then Drools 5 will work fine with Java 8.

[Pete Yan]

Thanks very much for your share. It has resolve my problems.

I'm use drools5.6 and jdk8, found the same questions, the .drl compiler can not use Map or HashMap. Error like this:

java.lang.NoClassDefFoundError: com/xx/rule/Rule_rule_57497bdaf1566880f896efaa_865eb46b6ad7410eab166a448f72df53

 Add maven conf like this and resolved:

<dependency>
    your drools 5 jars...
</dependency>

<dependency>
    <groupId>org.eclipse.jdt.core.compiler</groupId>
    <artifactId>ecj</artifactId>
    <version>4.5.1</version>
</dependency>

在 2016年2月19日星期五 UTC+8下午7:24:08，Karun Nadarajah写道：

[Edward Cai]

Hello Pete,

Could you please share the source code how you make drools 5 work with JDK 1.8?

Very appreciated!
Edward

[Pete Yan]

As I said, you need not to change your java code. 

Just add the maven pom config. The reason as Karun said because of  drools compiler. So you need just one thing that is change the drools5 compiler.
在 2016年6月28日星期二 UTC+8上午12:20:11，Edward Cai写道：

[Shailesh Singh]

Hi Pete,

I did the same but things are not moving there is a ecj-.*.jar in tomcat too do i need to change to same version too.I will post my pom file as soon as i reach the ofice.

[Sadhana]

Hi Karun,

I did upgrade to eclipse compiler to 4.4 and see the corresponding ecj-4.4.jar generated in my maven dependencies.

However, I am still getting the wrong class format exception:

Caused by: org.eclipse.jdt.internal.compiler.classfmt.ClassFormatException.

I tried using different versions of drools including 6.4.0.Final, 5.0.1 as well - but the issue persists. 

I get this error when I try using the Stateless kie session but not with the stateful kie session.

Any thoughts?

Best Regards,

Sadhana