Java - The SortedSet Interface

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The SortedSet interface extends Set and declares the behavior of a set sorted in an ascending order. In addition to those methods defined by Set, the SortedSet interface declares the methods summarized in the following table −

Several methods throw a NoSuchElementException when no items are contained in the invoking set. A ClassCastException is thrown when an object is incompatible with the elements in a set.

A NullPointerException is thrown if an attempt is made to use a null object and null is not allowed in the set.

Sr.No.	Method & Description
1	Comparator comparator( ) Returns the invoking sorted set's comparator. If the natural ordering is used for this set, null is returned.
2	Object first( ) Returns the first element in the invoking sorted set.
3	SortedSet headSet(Object end) Returns a SortedSet containing those elements less than end that are contained in the invoking sorted set. Elements in the returned sorted set are also referenced by the invoking sorted set.
4	Object last( ) Returns the last element in the invoking sorted set.
5	SortedSet subSet(Object start, Object end) Returns a SortedSet that includes those elements between start and end.1. Elements in the returned collection are also referenced by the invoking object.
6	SortedSet tailSet(Object start) Returns a SortedSet that contains those elements greater than or equal to start that are contained in the sorted set. Elements in the returned set are also referenced by the invoking object.

Example

SortedSet have its implementation in various classes like TreeSet. Following is an example of a TreeSet class −

import java.util.*;
public class SortedSetTest {

   public static void main(String[] args) {
      // Create the sorted set
      SortedSet set = new TreeSet(); 

      // Add elements to the set
      set.add("b");
      set.add("c");
      set.add("a");

      // Iterating over the elements in the set
      Iterator it = set.iterator();

      while (it.hasNext()) {
         // Get element
         Object element = it.next();
         System.out.println(element.toString());
      }
   }
}

This will produce the following result −

Output

a
b
c