NavigableSet ceiling() method in Java

The ceiling() method of NavigableSet interface in Java is used to return the least element in this set greater than or equal to the given element, or null if there is no such element.

Syntax:

E ceiling(E ele)

Where, E is the type of elements maintained by this Set container.

Parameters: This function accepts a parameter ele which refers to type of element maintained by this Set container.

Return Value: It returns the least element in this set greater than or equal to the given element, or null if there is no such element.

Below programs illustrate the ceiling() method in Java:

Program 1: NavigableSet with integer elements.

// A Java program to demonstrate
// working of NavigableSet
import java.util.NavigableSet;
import java.util.TreeSet;

public class GFG {
    public static void main(String[] args)
    {
        NavigableSet<Integer> ns = new TreeSet<>();
        ns.add(0);
        ns.add(1);
        ns.add(2);
        ns.add(3);
        ns.add(4);
        ns.add(5);
        ns.add(6);

        System.out.println("Least element greater than"
               + " or equal to 4 is: " + ns.ceiling(4));
    }
}

Output:

Least element greater than or equal to 4 is: 4

Program 2: NavigableSet with string elements.

// A Java program to demonstrate
// working of NavigableSet
import java.util.NavigableSet;
import java.util.TreeSet;

public class GFG {
    public static void main(String[] args)
    {
        NavigableSet<String> ns = new TreeSet<>();
        ns.add("A");
        ns.add("B");
        ns.add("C");
        ns.add("D");
        ns.add("E");
        ns.add("F");
        ns.add("G");

        System.out.println("Least element greater than"
              + " or equal to D is: " + ns.ceiling("D"));
    }
}

Output:

Least element greater than or equal to D is: D

Reference: https://docs.oracle.com/javase/10/docs/api/java/util/NavigableSet.html#ceiling(E)