List vs Set vs Map in Java – Know the Difference!

 

Java’s Collections Framework is one of its most powerful tools — but it’s confusing at first.

Should you use a List, a Set, or a Map? 🤔
Here’s a beginner-friendly guide that clears it all up 👇

1. List – Ordered and Allows Duplicates

• Think of it like an array, but more flexible.

• Maintains insertion order

• Duplicates are allowed

Example - 

List<String> fruits = new ArrayList<>();

fruits.add("Apple");

fruits.add("Banana");

fruits.add("Apple");  // allowed!

Popular types:

• ArrayList

• LinkedList

 2. Set – Unique Values Only

• No duplicates allowed

• Doesn’t guarantee order (unless you use LinkedHashSet or TreeSet)

Example - 

Set<String> names = new HashSet<>();

names.add("Aarav");

names.add("Aarav");  // ignored!

Popular types:

• HashSet

• TreeSet

• LinkedHashSet