Question

What is Hashtables used for in Java? Further more please give examples of simple usage of Hashtables.

Answer 1

Map<Integer,String> map = new HashMap<Integer,String>();
map.put(1, "One");
map.put(2, "Two");
map.put(10, "Ten");
...

int n = ... // some number
String s = map.get(n);
if(s == null)
   System.out.println("No entry was found for " + n);
else
   System.out.println(n + " is " + s);

Note that there is standard Java class called Hashtable, however it recommended not to use it. Best practice is to create instance of HashMap (which is a standard implementation of a hash-table) and use it through its interface Map.