The ArrayList<E> class

• Generic class: ArrayList<E> collects objects of type E
• E cannot be a primitive type
  
• add appends to the end
  

  ArrayList<String> countries = new ArrayList<String>();
  countries.add("Belgium");
  countries.add("Italy");
  countries.add("Thailand");
  

• since Java version 7 one can "replace the type arguments required to invoke the constructor of a generic class with an empty set of type parameters (<>) as long as the compiler can infer the type arguments from the context. This pair of angle brackets is informally called the diamond."
  Thus, the same code can be written as:
  

  ArrayList<String> countries = new ArrayList<>();
  countries.add("Belgium");
  countries.add("Italy");
  countries.add("Thailand");