Android: gradle configuration of object-diff : crash when run application

[svakulenko]

Hi

i try to use this library, let looks what we have :

build.gradle :
...
compile 'org.slf4j:slf4j-api:1.7.12'
compile 'eu.lp0.slf4j:slf4j-android:1.7.12-0'
compile 'de.danielbechler:java-object-diff:0.93'

logcat crash :

12-09 14:44:51.278 E/AndroidRuntime(15723): java.lang.NoClassDefFoundError: Failed resolution of: Ljava/beans/Introspector;
12-09 14:44:51.278 E/AndroidRuntime(15723): at de.danielbechler.diff.introspection.StandardIntrospector.getBeanInfo(StandardIntrospector.java:71)
12-09 14:44:51.278 E/AndroidRuntime(15723): at de.danielbechler.diff.introspection.StandardIntrospector.internalIntrospect(StandardIntrospector.java:53)
12-09 14:44:51.278 E/AndroidRuntime(15723): at de.danielbechler.diff.introspection.StandardIntrospector.introspect(StandardIntrospector.java:42)
12-09 14:44:51.278 E/AndroidRuntime(15723): at de.danielbechler.diff.introspection.IntrospectionService.typeInfoForNode(IntrospectionService.java:90)
12-09 14:44:51.278 E/AndroidRuntime(15723): at de.danielbechler.diff.differ.BeanDiffer.compareUsingIntrospection(BeanDiffer.java:110)
12-09 14:44:51.278 E/AndroidRuntime(15723): at de.danielbechler.diff.differ.BeanDiffer.compareUsingAppropriateMethod(BeanDiffer.java:104)
12-09 14:44:51.278 E/AndroidRuntime(15723): at de.danielbechler.diff.differ.BeanDiffer.compare(BeanDiffer.java:85)
12-09 14:44:51.278 E/AndroidRuntime(15723): at de.danielbechler.diff.differ.DifferDispatcher.compare(DifferDispatcher.java:188)
12-09 14:44:51.278 E/AndroidRuntime(15723): at de.danielbechler.diff.differ.DifferDispatcher.compareWithCircularReferenceTracking(DifferDispatcher.java:158)
12-09 14:44:51.278 E/AndroidRuntime(15723): at de.danielbechler.diff.differ.DifferDispatcher.compare(DifferDispatcher.java:145)
12-09 14:44:51.278 E/AndroidRuntime(15723): at de.danielbechler.diff.differ.DifferDispatcher.dispatch(DifferDispatcher.java:93)
12-09 14:44:51.278 E/AndroidRuntime(15723): at de.danielbechler.diff.ObjectDiffer.compare(ObjectDiffer.java:49)

Could you can give me a tip how to make it work ?

Thanks

[SQiShER]

Per default java-object-diff uses the java.beans.Introspector to resolve properties and their corresponding getters and setters from the types its trying to compare. It looks like the AndroidRuntime doesn't come with this class. That's something I wasn't aware of. The only way around that would be to implement a custom introspector, which doesn't rely on the java.beans class and either uses something similar from the AndroidRuntime or just plain old reflection.

The StandardIntrospector would be a good starting point. Basically all you'd have to do would be to implement the method TypeInfo introspect(Class<?> type) and populate the TypeInfo with information about the available properties of the given type.

The resulting Introspector can then be configured via ObjectDifferBuilder.

Come to think of it, now that I know that Android doesn't ship with java.beans.Introspector, I think it makes sense to change the default to use regular reflection and perhaps offer alternative implementations for people who rely on the performance advantages of the more advanced introspector. But for now, I'm afraid you have to build your own solution. 😞