? TreeSet in Java

? Quick Overview

TreeSet is a class in Java that implements the SortedSet interface. It stores unique elements in sorted order and internally uses a Red-Black Tree.

? Key Concepts

Does not allow duplicate elements
Elements are stored in sorted (ascending) order
Allows null only once (and often avoided)
Not synchronized by default
Slower than HashSet but maintains order

? Interactive Playground

Type a number and click Add. Watch how it sorts automatically and rejects duplicates!

Current Set: []

? Syntax / Theory

? View Code Example

// Creating a TreeSet of Integer type
TreeSet<Integer> numbers = new TreeSet<>();

? Code Example(s)

? View Code Example

// Demonstration of TreeSet operations
import java.util.TreeSet;

public class Main {
public static void main(String[] args) {
TreeSet<Integer> set = new TreeSet<>();

set.add(50);
set.add(10);
set.add(30);
set.add(10);

System.out.println(set);
}
}

?️ Live Output / Explanation

Output

[10, 30, 50]

Elements are automatically sorted and duplicate values are ignored.

✅ Tips & Best Practices

Use TreeSet when sorted data is required
Avoid null values to prevent exceptions
Prefer HashSet if ordering is not needed
Use Comparator for custom sorting

? Try It Yourself

Create a TreeSet of Strings
Add names in random order
Print the TreeSet and observe sorting
Apply a custom Comparator