I use com.android.tools.build:gradle:2.0.0-alpha3 and gradle 2.8 before I update to Android Studio 2.0 preview 5. It works fine.
After I update to 2.0 preview 5,it t
There's a quick fix listed on google plus by the android dev team in the comments (post).
Set dexInProcess equal to false in your build.gradle:
dexOptions { javaMaxHeapSize "4g" dexInProcess false //the magic line }