Also, this could be due to trying to access a class' method directly rather than from instantiating it, such as:
int returnVal = SomeViewModelClass.updateRecord(table, values, where);
This will result in the error: "Non-static method cannot be referenced from static context"
So, ensure that you have instantiated it appropriately, in this case like:
private SomeViewModelClass mSomeViewModelClass;
.
.
.
mSomeViewModelClass = ViewModelProviders.of(this).get(SomeViewModelClass.class);
I've had this happen, generated the error, when I deleted the leading letter, in this case "m", from the instance name or from forgetting to instantiate. So, you might not see this immediately and bang your head on the desk for a while, which is what I just did that brought me to submit this answer!