Hi,today i learned about the java collections in java.I will share some points in java collections.
What is Java Collections ?
The java collections is a framework that provides a set of interfaces and classes to store,manage, and manipulate groups of objects efficiently.
Core Components of Java Collections :
The framework is mainly divided into three major interfaces:
1) List – Ordered and Allows Duplicates
- A List maintains insertion order and allows duplicate elements.
Common Implementations:
- ArrayList
- LinkedList
Example:
List list = new ArrayList<>();
list.add("Apple");
list.add("Apple"); // duplicates allowed
Use List when:
- Order matters
- You need index-based access
2) Set – No Duplicates Allowed
- A Set does not allow duplicate elements.
Common Implementations:
- HashSet (fast, unordered)
- TreeSet (sorted)
Example:
Set set = new HashSet<>();
set.add("Apple");
set.add("Apple"); // ignored
Use Set when:
- You want unique values
- Duplicates must be avoided
3) Map – Key-Value Pair Storage
- A Map stores data in key-value format.
Common Implementations:
- HashMap
- TreeMap Example: Map map = new HashMap<>(); map.put(1, "Arul"); map.put(2, "John");
Use Map when:
- You need to associate one value with another
- Fast lookup using keys is required
Real-World Use Cases
Java Collections are everywhere:
- Storing user data in applications
- Managing product lists in e-commerce
- Handling logs and transactions
- Processing large datasets