This is very important both for cache locality and for minimizing garbage collector pressure.

   public class StringList extends java.util.ArrayList<String> {
       public static void main(String[] args) throws Exception {
           StringList asStringList = new StringList();
           java.util.ArrayList<Integer> asArrayList = (java.util.ArrayList<Integer>)(Object)asStringList;
           System.out.println("It knows it's an ArrayList<String>: " + java.util.Arrays.toString(((java.lang.reflect.ParameterizedType)asArrayList.getClass().getGenericSuperclass()).getActualTypeArguments()));
           System.out.println("But you can save and store Integers in it:");
           asArrayList.add(42);
           System.out.println(asArrayList.get(0));
           System.out.println(asArrayList.get(0).getClass());
           System.out.println("Unless it's static type is StringArrayList:");
           System.out.println(asStringList.get(0));
       }
   }

   It knows it's an ArrayList<String>: [class java.lang.String]
   But you can save and store Integers in it:
   42
   class java.lang.Integer
   Unless it's static type is StringArrayList:
   Exception in thread "main" java.lang.ClassCastException: class java.lang.Integer cannot be cast to class java.lang.String (java.lang.Integer and java.lang.String are in module java.base of loader 'bootstrap')
    at StringList.main(StringList.java:11)

Academic jargon isn't invented to be elitist, it's invented to improve communication.

(of course there's a good chance you understand this already, and you're just making a dumb joke, but I figured I'd explain this anyway for the benefit of everyone reading)

To be more precise: in Java, generics on class/method/field declarations are available at runtime via reflection. The issue is that they aren’t available for instances. So a java.util.ArrayList<java.lang.String> instance is indistinguishable at runtime from a java.util.ArrayList<java.lang.Object> instance