I am having problems adding knowledge packages to a kb. For instance I create a kb n' add this drl:

package test

rule "abc"

then System.out.println("abc");

end

then I want to add another drl with the same package.

package test

rule "123"

then System.out.println("123");

end

this is the code i'm using for adding

public static void add(KnowledgeBase kb, String content) throws Exception {

(1) KnowledgeBuilder builder = KnowledgeBuilderFactory.newKnowledgeBuilder(kb);

(2) builder.add(

ResourceFactory.newByteArrayResource(content.getBytes()),

ResourceType.DRL);

if (builder.hasErrors())

throw new Exception(builder.getErrors().toString());

kb.addKnowledgePackages(builder.getKnowledgePackages());

}

please notice i am creating a new builder every time and the kb is passed in on (1)

the first call to add works fine. but on the second i get a NullPointerException on line (2)

java.lang.NullPointerException

at org.drools.rule.builder.dialect.java.PackageStore.write(PackageStore.java:47)

at org.drools.commons.jci.compilers.EclipseJavaCompiler$3.acceptResult(EclipseJavaCompiler.java:350)

at org.eclipse.jdt.internal.compiler.Compiler.compile(Compiler.java:474)

at org.drools.commons.jci.compilers.EclipseJavaCompiler.compile(EclipseJavaCompiler.java:358)

at org.drools.commons.jci.compilers.AbstractJavaCompiler.compile(AbstractJavaCompiler.java:49)

at org.drools.rule.builder.dialect.java.JavaDialect.compileAll(JavaDialect.java:369)

at org.drools.compiler.DialectCompiletimeRegistry.compileAll(DialectCompiletimeRegistry.java:53)

at org.drools.compiler.PackageRegistry.compileAll(PackageRegistry.java:71)

at org.drools.compiler.PackageBuilder.compileAll(PackageBuilder.java:869)

at org.drools.compiler.PackageBuilder.addPackage(PackageBuilder.java:826)

at org.drools.compiler.PackageBuilder.addPackageFromDrl(PackageBuilder.java:404)

at org.drools.compiler.PackageBuilder.addKnowledgeResource(PackageBuilder.java:586)

at org.drools.builder.impl.KnowledgeBuilderImpl.add(KnowledgeBuilderImpl.java:37)