Collections

https://docs.oracle.com/javase/7/docs/api/java/util/Collection.html

Interface Collection, is the root interface in the collection hierarchy. A collection represents a group of objects, known as its elements.

There're three major interfaces in Java Collections Framework: List, Set and Map

In Java, the collection interface is a group of objects, with duplicates allowed.

1. Set: No duplicates;
2. List: allows duplicates, and introduces positional indexing
3. Map: A collection of pairs(key, value). No duplicate keys allowed.

We are users of the Collections. The first thing we need to care about, as a programmer, is what kind of operations we can perform on them.

• Addition (Insertion)
• Removal (Deletion)
• Sorting
• Searching
• Iteration (Traversal)
• Copying (Cloning)