Java SortedSet Interface

In this tutorial, we will learn about the SortedSet interface in Java and its methods with the help of an example.

The SortedSet interface of the Java Collections system is used to store components with some order in a set.

It extends the Set interface.

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Class that implements SortedSet

In order to use the functionalities of the SortedSet interface, we need to use the TreeSet class that implements it.

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How to use SortedSet?

To use SortedSet, we must import the java.util.SortedSet package first.

// SortedSet implementation by TreeSet class
SortedSet<String> animals = new TreeSet<>();

We have created a sorted set called animals using the TreeSet class.

Here we have used no contentions to make an arranged set. Consequently the set will be arranged normally.

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Methods of SortedSet

The SortedSet interface incorporates all the strategies for the Set interface. This is on the grounds that Set is a super interface of SortedSet.

Other than strategies remembered for the Set interface, the SortedSet interface additionally incorporates these methods:

• comparator() – returns a comparator that can be used to order elements in the set
• first() – returns the first element of the set
• last() – returns the last element of the set
• headSet(element) – returns all the elements of the set before the specified element
• tailSet(element) – returns all the elements of the set after the specified element including the specified element
• subSet(element1, element2) – returns all the elements between the element1 and element2 including element1

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Implementation of SortedSet in TreeSet Class

import java.util.SortedSet;
import java.util.TreeSet;

class Main {

    public static void main(String[] args) {
        // Creating SortedSet using the TreeSet
        SortedSet<Integer> numbers = new TreeSet<>();

        // Insert elements to the set
        numbers.add(1);
        numbers.add(2);
        numbers.add(3);
        numbers.add(4);
        System.out.println("SortedSet: " + numbers);

        // Access the element
        int firstNumber = numbers.first();
        System.out.println("First Number: " + firstNumber);

        int lastNumber = numbers.last();
        System.out.println("Last Number: " + lastNumber);

        // Remove elements
        boolean result = numbers.remove(2);
        System.out.println("Is the number 2 removed? " + result);
    }
}

Output

SortedSet: [1, 2, 3, 4]
First Number: 1
Last Number: 4
Is the number 2 removed? true

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Now that we know about the SortedSet interface, we will learn about its implementation using the TreeSet class.

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Java Set