en/java-collections-overview

Java Collections Overview

Java Collections Framework provides a rich set of classes and interfaces to store and manipulate groups of objects. It is designed to be highly efficient and flexible, making it a fundamental part of Java programming.

Key Components

Classes: ArrayList, LinkedList, HashMap, HashSet, TreeMap, TreeSet, etc.
Interfaces: Collection, List, Set, Map, Queue, Deque, etc.

Features

Type Safety: Collections can store objects of any type, but the framework ensures that only objects of the specified type can be added.
Performance: Collections are optimized for performance, with different implementations suitable for different use cases.
Iterability: Collections can be easily iterated over using loops or iterators.

Common Use Cases

Lists: Use ArrayList for random access and LinkedList for frequent insertions and deletions.
Sets: Use HashSet for uniqueness and TreeSet for sorted order.
Maps: Use HashMap for key-value pairs and TreeMap for sorted keys.

Example

Here's a simple example using ArrayList:

import java.util.ArrayList;

public class Main {
    public static void main(String[] args) {
        ArrayList<String> list = new ArrayList<>();
        list.add("Apple");
        list.add("Banana");
        list.add("Cherry");

        for (String fruit : list) {
            System.out.println(fruit);
        }
    }
}

For more information on Java Collections, you can read our detailed guide on Java Collections Framework.