SortedSet tailSet() method in Java

Last Updated : 30 Sep, 2018

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)

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