is it ok to change the value from outside a Map?

Question

So i have a code snippet here. I go this issue while i was discussing some code with my friend

Map<Integer , List<String>> myMap = new HashMap<Integer , List<String>>();
List<String> list =  new ArrayList<String>();
myMap.put(45,list);
List<String> lst = myMap.get(45);
lst.add("String1");
lst.add("String2");
lst.add("String3");
System.out.println(myMap.get(45));

My question here is. -> If its ok to modify the list outside the map through another reference? I am asking from OOP design point of view.

Answer 1

That is completely ok, IMHO

When you write

List<String> lst = myMap.get(45);

Still it is refering to the value in the map, for the key 45.

Once you get the value(reference to the list), It's up to you what you are doing with it.