i just added JAVA_Home to my environments and the error changed to this:
Execution failed for task ‘:transformClassesWithJarMergingForDebug’.
com.android.build.api.transform.TransformException: java.util.zip.ZipException: duplicate entry: android/support/v13/view/DragStartHelper$OnDragStartListener.class
so I guessing is best to un-install java and then install a whole new JDK as you suggested before. if I was following correctly???.