#java #datastructures #programming #collections

Java Concepts I’m Mastering – Part 13: HashMap in Java (Key-Value Data Storage) Continuing my journey of mastering Java fundamentals. Today’s concept: HashMap — a powerful way to store and access data using key-value pairs. What is a HashMap? A HashMap stores data in the form of: Key → Value Each key is unique and maps to a specific value. Example: "Java" → 1995 "Python" → 1991 Creating a HashMap import java.util.HashMap; HashMap<String, Integer> languages = new HashMap<>(); languages.put("Java", 1995); languages.put("Python", 1991); languages.put("C++", 1985); Accessing Values System.out.println(languages.get("Java")); Output: 1995 Useful HashMap Methods languages.put("Go", 2009); // add element languages.get("Python"); // access value languages.remove("C++"); // delete element languages.containsKey("Java"); // check key languages.size(); // total elements Why HashMap is Powerful Very fast lookups Stores structured data Used heavily in real applications Examples: Caching systems Datab