The java.util.concurrent.ConcurrentSkipListSet.ceiling() method is an in-built function in Java which returns the least element in this set greater than or equal to the given element, or null if there is no such element.
Syntax:
ConcurrentSkipListSet.ceiling(E e)
Parameters: The function accepts a single parameter e i.e. the element to match.
Return Value: The function returns the least element greater than or equal to e, or null if there is no such element.
Exception: The function shows the following exceptions:
Below programs illustrate the ConcurrentSkipListSet.ceiling() method:
Program 1: To find ceiling of a number.
// Java Program Demonstrate ceiling()// method of ConcurrentSkipListSet   import java.util.concurrent.*;  class ConcurrentSkipListSetCeilingExample1 {    public static void main(String[] args)    {        // Creating a set object        ConcurrentSkipListSet<Integer> Lset =                         new ConcurrentSkipListSet<Integer>();          // Adding elements to this set        Lset.add(45);        Lset.add(72);        Lset.add(31);        Lset.add(13);        Lset.add(89);          // Printing elements of the set        System.out.println("The set contains: ");        for (Integer i : Lset)            System.out.print(i + " ");          // Ceiling of 35        System.out.println("\nCeiling of 35: " + Lset.ceiling(35));          // Ceiling of 100        System.out.println("\nCeiling of 100: " + Lset.ceiling(100));    }} |
The set contains: 13 31 45 72 89 Ceiling of 35: 45 Ceiling of 100: null
Program 2: To show NullPointerException in ceiling().
// Java Program Demonstrate ceiling()// method of ConcurrentSkipListSet  import java.util.concurrent.*;import java.io.*;  class ConcurrentSkipListSetCeilingExample2 {    public static void main(String[] args) throws IOException    {        // Creating a set object        ConcurrentSkipListSet<Integer> Lset =                             new ConcurrentSkipListSet<Integer>();          // Adding elements to this set        Lset.add(45);        Lset.add(72);        Lset.add(31);        Lset.add(13);        Lset.add(89);          try {            // Ceiling of null            System.out.println("Ceiling of null: " + Lset.ceiling(null));        }          catch (Exception e) {            System.out.println("Exception : " + e);        }    }} |
Exception : java.lang.NullPointerException
Reference : https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ConcurrentSkipListSet.html#ceiling(E)
