Empty ArrayList equals null

No.

An ArrayList can be empty (or with nulls as items) an not be null. It would be considered empty. You can check for am empty ArrayList with:

ArrayList arrList = new ArrayList();
if(arrList.isEmpty())
{
    // Do something with the empty list here.
}

Or if you want to create a method that checks for an ArrayList with only nulls:

public static Boolean ContainsAllNulls(ArrayList arrList)
{
    if(arrList != null)
    {
        for(object a : arrList)
            if(a != null) return false;
    }

    return true;
}