collections java code example

Example 1: import collections in java

import java.util.Collection;

Example 2: collection framework

LIST: Can store duplicate values,
      Keeps the insertion order. 
      It allows multiple null values, 
      Also we can read a certain value by index.
- ArrayList not syncronized, array based class 
- LinkedList not synchronized, doubly linked
- Vector is synchronized, thread safe

SET: Can only store unique values, 
     And does not maintain order
- HashSet can have null, order is not guaranteed
- LinkedHashSet can have null and keeps the order 
- TreeSet sorts the order and don't accept null 

QUQUE : Accepts duplicates, 
        Doesn't have index num,
        First in first our order.  
       
MAP : is a (key-value format) 
      and keys are always unique, 
      and value can be duplicated. 
- HashTable don't have null key, sychronized(thread-safe)
- LinkedHashMap can have null key, keeps order
- HasHMap can have null key, order is not guaranteed
- TreeMap doesn't have null key and keys are sorted

Example 3: declaring collection java

import java.util.Collection;
import java.util.ArrayList;
Collection<Integer> fibonacci = new Arraylist<Integer>();

Example 4: how to define a collection in java

List<String> list = Arrays.asList("Lars", "Simon");

Example 5: what type of collections used

Depending on the data that I am working with, I use
Arrays, Lists, Sets, Maps.

Example 6: collection api

Postman is a Client toolto work with APIs to send
requests get responseOrganize the requestsCollection
in Postman is a top level folder
to store your requests so we can run any time