android - "Conversion to Dalvik format failed with error 1" on external JAR

In my Android application in Eclipse I get the following error.

UNEXPECTED TOP-LEVEL EXCEPTION:
java.lang.IllegalArgumentException: already added: Lorg/xmlpull/v1/XmlPullParser;
....
Conversion to Dalvik format failed with error 1

This error only appears when I add a specific external JAR file to my project. I searched for a long time for the possible solution, but none of the possible solutions work. I even tried to change to Android 1.6 instead of 1.5 (the current version I use).

Answer

I solved the problem.

This is a JAR file conflict.

It seems that I have two JAR files on my buildpath that include the same package and classes.

smack.jar and android_maps_lib-1.0.2

Deleting this package from one of the JAR files solved the problem.