NavigableSet Interface in Java

Last Updated: 16 July, 2023

In Java, NavigableSet is an interface that extends the SortedSet interface and provides additional navigation methods for accessing elements in a sorted set. It is part of the Java Collections Framework and is available from Java 6 onward.

A NavigableSet maintains a sorted order of its elements, and it allows efficient retrieval of elements based on their relative position in the set. It provides methods to navigate through the set in both ascending and descending order, perform range queries, and find closest matches for a given value.

NavigableSet declaration:

 public interface NavigableSet<E> extends SortedSet<E>

Here, E defines the type of elements that the Set will contain.

The NavigableSet interface is implemented by the TreeSet class in the Java Collections Framework. TreeSet provides a sorted set implementation based on a binary search tree, which allows efficient navigation and retrieval operations.

Here's an example of using NavigableSet with TreeSet:

  
  import java.util.NavigableSet;
  import java.util.TreeSet;
  public class NavigableSetExample {
      public static void main(String[] args) {
          NavigableSet<Integer> set = new TreeSet<>();
            
          // Adding elements to the set
          set.add(10);
          set.add(20);
          set.add(30);
          set.add(40);
          set.add(50);
          
          System.out.println("Set: " + set);
          
          // Using NavigableSet methods
          System.out.println("lower(30): " + set.lower(30));
          System.out.println("floor(35): " + set.floor(35));
          System.out.println("ceiling(35): " + set.ceiling(35));
          System.out.println("higher(30): " + set.higher(30));
          
          System.out.println("pollFirst(): " + set.pollFirst());
          System.out.println("pollLast(): " + set.pollLast());
          
          System.out.println("Set after poll operations: " + set);
      }
  }

Output

Set: [10, 20, 30, 40, 50]
lower(30): 20
floor(35): 30
ceiling(35): 40
higher(30): 40
pollFirst(): 10
pollLast(): 50
Set after poll operations: [20, 30, 40]

NavigableSet Interface in Java

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