adding two different list in one in one go itself in java

adding two different list in one in one go itself in java

I am getting a list return type from two methods and I am further summing
up that two list into a third list like as shown below
List<aaa> total = new ArrayList<aaa>();
total.addAll(activeasdf());//method return type is of list
total.addAll(usersdfre());
Now please advise can't i do this in one line as why to add three line of
code for doing this