The NavigableSet Interface : NavigableSet « Collections « Java Tutorial

1. Java Tutorial
2. Collections
3. NavigableSet

The NavigableSet interface is a subinterface of SortedSet that provides methods for searching for elements.

java.util.TreeSet is an implementation of NavigableSet.

import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.NavigableSet;
import java.util.TreeSet;

public class NavigableSetDemo {

  public static void main(String[] args) {
    List<Integer> list = Arrays.asList(3, 2, 4, 1, 5);
    NavigableSet<Integer> ns = new TreeSet<Integer>(list);
    System.out.println("Ascending order (default): " + ns);

    Iterator<Integer> descendingIterator = ns.descendingIterator();
    StringBuilder sb = new StringBuilder("Descending order: ");
    while (descendingIterator.hasNext()) {
      int m = descendingIterator.next();
      sb.append(m + " ");
    }
    System.out.println(sb);

    int greatest = ns.lower(3);
    System.out.println("Lower of 3 = " + greatest);

    int smallest = ns.higher(3);
    System.out.println("Higher of 3 = " + smallest);
  }
}

Ascending order (default): [1, 2, 3, 4, 5]
Descending order: 5 4 3 2 1 
Lower of 3 = 2
Higher of 3 = 4