Drools Android Integration

Question

I am working on drools implementation in android, stuck in an issue

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.decurtis.drooldemo/com.decurtis.drooldemo.MainActivity}: java.lang.RuntimeException: Unable to instantiate object for class 'org.drools.android.DexPackageClassLoader' with constructor public org.drools.android.DexPackageClassLoader(org.drools.core.rule.JavaDialectRuntimeData,java.lang.ClassLoader) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707) at android.app.ActivityThread.-wrap12(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:154) at android.app.ActivityThread.main(ActivityThread.java:6077) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756) Caused by: java.lang.RuntimeException: Unable to instantiate object for class 'org.drools.android.DexPackageClassLoader' with constructor public org.drools.android.DexPackageClassLoader(org.drools.core.rule.JavaDialectRuntimeData,java.lang.ClassLoader) at org.drools.core.util.ClassUtils.instantiateObject(ClassUtils.java:272) at org.drools.core.rule.JavaDialectRuntimeData.makeClassLoader(JavaDialectRuntimeData.java:618) at org.drools.core.rule.JavaDialectRuntimeData.onAdd(JavaDialectRuntimeData.java:243) at org.drools.compiler.rule.builder.dialect.java.JavaDialect.(JavaDialect.java:187) at org.drools.compiler.rule.builder.dialect.java.JavaDialectConfiguration.newDialect(JavaDialectConfiguration.java:91) at org.drools.compiler.builder.impl.KnowledgeBuilderConfigurationImpl.buildDialectRegistry(KnowledgeBuilderConfigurationImpl.java:392) at org.drools.compiler.compiler.PackageRegistry.(PackageRegistry.java:55) at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.newPackage(KnowledgeBuilderImpl.java:1571) at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.initPackageRegistry(KnowledgeBuilderImpl.java:1044) at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.createPackageRegistry(KnowledgeBuilderImpl.java:1015) at org.drools.compiler.builder.impl.CompositeKnowledgeBuilderImpl.initPackageRegistries(CompositeKnowledgeBuilderImpl.java:297) at org.drools.compiler.builder.impl.CompositeKnowledgeBuilderImpl.buildPackages(CompositeKnowledgeBuilderImpl.java:116) at org.drools.compiler.builder.impl.CompositeKnowledgeBuilderImpl.build(CompositeKnowledgeBuilderImpl.java:105) at org.drools.compiler.kie.builder.impl.AbstractKieModule.buildKnowledgePackages(AbstractKieModule.java:244) at org.drools.compiler.kie.builder.impl.AbstractKieProject.verify(AbstractKieProject.java:64) at org.drools.compiler.kie.builder.impl.KieBuilderImpl.buildKieProject(KieBuilderImpl.java:230) at org.drools.compiler.kie.builder.impl.KieBuilderImpl.buildAll(KieBuilderImpl.java:198) at com.decurtis.drooldemo.MainActivity.kieExecute63(MainActivity.java:81) at com.decurtis.drooldemo.MainActivity.onCreate(MainActivity.java:41) at android.app.Activity.performCreate(Activity.java:6662) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)  at android.app.ActivityThread.-wrap12(ActivityThread.java)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)  at android.os.Handler.dispatchMessage(Handler.java:102)  at android.os.Looper.loop(Looper.java:154)  at android.app.ActivityThread.main(ActivityThread.java:6077)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)  Caused by: java.lang.reflect.InvocationTargetException at java.lang.reflect.Constructor.newInstance0(Native Method) at java.lang.reflect.Constructor.newInstance(Constructor.java:430) at org.drools.core.util.ClassUtils.instantiateObject(ClassUtils.java:270) at org.drools.core.rule.JavaDialectRuntimeData.makeClassLoader(JavaDialectRuntimeData.java:618)  at org.drools.core.rule.JavaDialectRuntimeData.onAdd(JavaDialectRuntimeData.java:243)  at org.drools.compiler.rule.builder.dialect.java.JavaDialect.(JavaDialect.java:187)  at org.drools.compiler.rule.builder.dialect.java.JavaDialectConfiguration.newDialect(JavaDialectConfiguration.java:91)  at org.drools.compiler.builder.impl.KnowledgeBuilderConfigurationImpl.buildDialectRegistry(KnowledgeBuilderConfigurationImpl.java:392)  at org.drools.compiler.compiler.PackageRegistry.(PackageRegistry.java:55)  at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.newPackage(KnowledgeBuilderImpl.java:1571)  at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.initPackageRegistry(KnowledgeBuilderImpl.java:1044)  at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.createPackageRegistry(KnowledgeBuilderImpl.java:1015)  at org.drools.compiler.builder.impl.CompositeKnowledgeBuilderImpl.initPackageRegistries(CompositeKnowledgeBuilderImpl.java:297)  at org.drools.compiler.builder.impl.CompositeKnowledgeBuilderImpl.buildPackages(CompositeKnowledgeBuilderImpl.java:116)  at org.drools.compiler.builder.impl.CompositeKnowledgeBuilderImpl.build(CompositeKnowledgeBuilderImpl.java:105)  at org.drools.compiler.kie.builder.impl.AbstractKieModule.buildKnowledgePackages(AbstractKieModule.java:244)  at org.drools.compiler.kie.builder.impl.AbstractKieProject.verify(AbstractKieProject.java:64)  at org.drools.compiler.kie.builder.impl.KieBuilderImpl.buildKieProject(KieBuilderImpl.java:230)  at org.drools.compiler.kie.builder.impl.KieBuilderImpl.buildAll(KieBuilderImpl.java:198)  at com.decurtis.drooldemo.MainActivity.kieExecute63(MainActivity.java:81)  at com.decurtis.drooldemo.MainActivity.onCreate(MainActivity.java:41)  at android.app.Activity.performCreate(Activity.java:6662)  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599)  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)  at android.app.ActivityThread.-wrap12(ActivityThread.java)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)  at android.os.Handler.dispatchMessage(Handler.java:102)  at android.os.Looper.loop(Looper.java:154)  at android.app.ActivityThread.main(ActivityThread.java:6077)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)  Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.io.File.getAbsolutePath()' on a null object reference at org.drools.android.MultiDexClassLoader.(MultiDexClassLoader.java:70) 07-27 04:43:48.294 16631-16631/com.decurtis.drooldemo E/AndroidRuntime: at org.drools.android.DexPackageClassLoader.(DexPackageClassLoader.java:44)

Code : I am using drools 6.5.0 version and getting above error.

KieServices   ks  = KieServices.Factory.get();
    KieRepository kr  = ks.getRepository();
    KieFileSystem kfs = ks.newKieFileSystem();
    kfs.write(ResourceFactory.newClassPathResource("rules/Fire.drl", Fire.class));
    KieBuilder kb = ks.newKieBuilder(kfs);
    kb.buildAll(); // kieModule is automatically deployed to KieRepository if successfully built.
    if (kb.getResults().hasMessages(Message.Level.ERROR)) {
        throw new RuntimeException("Build Errors:\n" + kb.getResults().toString());
    }

    KieContainer kContainer = ks.newKieContainer(kr.getDefaultReleaseId());

    KieSession kSession = kContainer.newKieSession();

    System.out.println("Fire All Rules...");
    kSession.fireAllRules();
    kSession.dispose();

Have anyone experience this error, plz help me in out?

Answer 1

For the above exception add Janino to your classpath.

Imp: It seems that the dependencies that drools-android uses only work till API level 21. Post to that the native API they need has been blocked by Android. You can test this application on a phone with Android version 5.1 and it should work. Post that I too am searching for a solution