SortedSet Interface in Java

The SortedSet interface is present in java.util package that extends the Set interface, which maintains unique elements in sorted order, either by natural ordering or a custom comparator.

• Elements are maintained in ascending order by default.
• Ensures that no duplicate elements are present, consistent with the Set interface.
• Null elements are generally not allowed because sorting (natural/comparator) may cause NullPointerException.

Declaration

Since SortedSet is an interface, objects cannot be created directly. Use a class like TreeSet that implements it.

public interface SortedSet<E> extends Set<E>

[10, 20, 40, 50]
First element: 10
Last element: 50

Explanation:

• A TreeSet implements SortedSet.
• Elements are automatically sorted in ascending order.
• first() and last() return the smallest and largest elements, respectively.

Hierarchy of SortedSet

SortedSet interface extends the Set interface.

Performing Different Operations on SortedSet

1. Adding Elements

To add elements to a SortedSet, use the add() method.In a TreeSet, elements are automatically sorted in ascending order, duplicates are ignored, and null values are not allowed.

[A, B, C]

2. Accessing the Elements

We can access elements using methods such as contains(), first(), last(), etc.

Sorted Set is: [A, B, C]
Contains: D false
First Value: A
Last Value: C

3. Removing the Values

The values can be removed from the SortedSet using the remove() method.

Initial TreeSet: [A, B, C, D, E]
After removing element: [A, C, D, E]

4. Iterating through the SortedSet

There are various ways to iterate through the SortedSet. The most famous one is to use the enhanced for loop.

A, B, C, D, E, Z, 

Note: The class which implements the SortedSet interface is TreeSet.

Methods of SortedSet Interface

The following are the methods present in the SortedSet interface. Here, the “*” represents that the methods are part of the Set interface.