Map versus HashMap (Java Questions)

1. Why is a Map not the class to choose when you need to implement a name/value pair collection?
   Answer:
   This is because Map is an interface and not a concrete implementation .
2. What are the 3 interface types that have concrete Classes for the Collection Interface?
   Answer:
   The 3 concrete implementations are 1) Map 2) Set and 3) List.
3. Which collection would you use when you need to search for the objects based on a serial number?
   Answer:
   You should use a Map.
4. What is the natural order for a String?
   Answer:
   The natural order for a String will be standard alphabetical sort.
5. Which “Concrete Implementation Class” would you use if you had to keep track of which part was last accessed?
   Answer:
   LinkedHashMap.
6. What are the advantages of the ArrayList over the array?
   Answer:
   
   1. An ArrayList can grow dynamically
   2. It provides more powerful insertion and search mechanisms than arrays.
   
   
7. What is the correct way to declare the Collection’s type?
   Answer:
   List <String> myList = new ArrayList <String>();
8. What is the difference between Java 5 and pre-Java 5 collections?
   Answer:
   Pre-Java 5 collections were untyped.
9. How does Java 5 deal with primtive to Wrapper conversion?
   Answer:
   With Java 5, primitives still have to be wrapped before they are put into a Collection, but autoboxing takes of it for you.
10. What do collections and arrays have in common when it comes sorting and searching?
    Answer:
    Both collections and arrays can be sorted and searched using methods in the API.