Lecture 19.
Interface
-> set of methods
-> common functionality among a set of classes
Syntax: public class ClassName implements InterfaceName
Interface is more general than extends.
Map (interface)
Key
Value
An association between a key and a value. Always keysensitive.
Ex. Dictionary - a map
words - key
defintions - value
Ex. Phonebook - a map
names - key
numbers - value
HashMap (class)
-> implements Map
template -> 2 types ( one type for your keys and one for your values)
HashMap<String, Integer> phonebook = new HashMap<String, Integer>( );
Methods most commonly used: put and get, but also remove, containskey and size.
phonebook.put("Mehran", 7236059);
phonebook.put("Jenny", 8675309);
Integer MehranNumber = phonebook.get("Mehran");
phonebook.remove(key); //removes key AND value
phonebook.containskey(key); // returns a boolean
THINK of it as a bag where you put things in pairs. No order.
