right click on the working set you want and then click on Properties.
Select the project and Add it to the Working set content.
Select the project and Add it to the Working set content.
Project > Properties > Java Build Path > Libraries
and ensure that there is no android.jar or maps.jar directly included. You should only have Google Apis with at leastmaps.jar and android.jar as leaves.java.io.IOException: Unable to open sync connection!