The floor() method of java.util.concurrent.ConcurrentSkipListSet is an in-built function in Java which returns the greatest element in this set less than or equal to the given element, or null if there is no such element.
Syntax:
ConcurrentSkipListSet.floor(E e)
Parameter: The function accepts a single parameter e i.e. the value to match.
Return Value: The function returns the greatest element less than or equal to e, or null if there is no such element.
Exception: The function throws the following exceptions:
Below programs illustrate the ConcurrentSkipListSet.floor() method:
Program 1:
// Java program to demonstrate floor()// method of ConcurrentSkipListSet  import java.util.concurrent.*;  class ConcurrentSkipListSetFloorExample1 {    public static void main(String[] args)    {        // Creating a set object        ConcurrentSkipListSet<Integer>            Lset = new ConcurrentSkipListSet<Integer>();          // Adding elements to this set        for (int i = 10; i <= 50; i += 10)            Lset.add(i);          // Finding floor of 20 in the set        System.out.println("The floor of 20 in the set "                           + Lset.floor(20));          // Finding floor of 39 in the set        System.out.println("The floor of 39 in the set "                           + Lset.floor(39));          // Finding floor of 9 in the set        System.out.println("The floor of 10 in the set "                           + Lset.floor(9));    }} |
Output:
The floor of 20 in the set 20 The floor of 39 in the set 30 The floor of 10 in the set null
Program 2: Program to show NullPointerException in floor().
// Java program to demonstrate floor()// method of ConcurrentSkipListSet  import java.util.concurrent.*;  class ConcurrentSkipListSetFloorExample2 {    public static void main(String[] args)    {        // Creating a set object        ConcurrentSkipListSet<Integer>            Lset = new ConcurrentSkipListSet<Integer>();          // Adding elements to this set        for (int i = 10; i <= 50; i += 10)            Lset.add(i);          // Trying to find the floor of null        try {            System.out.println("The floor of null in the set "                               + Lset.floor(null));        }        catch (Exception e) {            System.out.println("Exception: " + e);        }    }} |
Output:
Exception: java.lang.NullPointerException
Reference: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ConcurrentSkipListSet.html#floor-E-
