I am sure many of you may see this error at sometime or the other when you are developing in Android o Eclipse. Most times, I have found this work for me.
In Eclipse, select the project causing the error- go to the menu project -> properties -> java build path -> libraries and remove all jars including the android jars.
Then, right click the project, go to android tools -> fix project properties. Then, add back any other external jars you wanted to add to the build path following the same menu project -> properties -> java build path -> libraries. To ensure there are no errors due to missing libraries.
Then, do a 'clean' on menu project and build again. It should work.
My guess is that when an incompatible android jar is used to compile this error is thrown. There may be many other scenarios too that cause thsi error... you can add them below