SortedSet tailSet() method in Java

The tailSet() method of SortedSet interface in Java is used to return a view of the portion of this set whose elements are greater than or equal to the parameter fromElement.

• The set returned by this method is backed by this set, so changes in the returned set are reflected in this set, and vice-versa.
• The set returned by this method supports all optional set operations that this set supports.

Note: The set returned by this method will throw an IllegalArgumentException if an attempt is made to insert an element outside its range.

Syntax:

SortedSet tailSet(E fromElement)

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

Parameters: This function accepts a single parameter fromElement which represent the low endpoint (inclusive) of the returned set.

Return Value: It returns the elements which are greater than or equal to the given argument fromElement.

Exceptions:

• ClassCastException : It throws a ClassCastException if fromElement is not compatible with this set’s comparator (or, if the set has no comparator, if fromElement does not implement Comparable).
• NullPointerException : It throws a NullPointerException if the parameter fromElement is null.
• IllegalArgumentException : It throws an IllegalArgumentException this set itself has a restricted range, and the parameter fromElement lies outside the bounds of the range.

Below programs illustrate the above method:

Program 1:

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

public class Main {
    public static void main(String[] args)
    {
        // Create a TreeSet and inserting elements
        SortedSet<Integer> s = new TreeSet<>();

        // Adding Element to SortedSet
        s.add(1);
        s.add(5);
        s.add(2);
        s.add(3);
        s.add(9);

        // Returning the set with elements
        // strictly less than the passed value
        System.out.print("Elements greater than or equal to 5 in set are : "
                         + s.tailSet(5));
    }
}

Output:

Elements greater than or equal to 5 in set are : [5, 9]

Program 2:

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

public class Main {
    public static void main(String[] args)
    {
        // Create a TreeSet and inserting elements
        SortedSet<String> s = new TreeSet<>();

        // Adding Element to SortedSet
        s.add("Geeks");
        s.add("For");
        s.add("Geeks");
        s.add("Code");
        s.add("It");

        // Returning the set with elements
        // strictly less than the passed value
        System.out.print("Element greater than or equal to G in set is : "
                         + s.tailSet("G"));
    }
}

Output:

Element greater than or equal to G in set is : [Geeks, It]

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