TreeSet descendingIterator() method in Java with Examples (original) (raw)

Last Updated : 31 Oct, 2023

The **descendingIterator() method of **java.util.TreeSet class is used to return an iterator over the elements in this set in descending order.
**Syntax:

public Iterator descendingIterator()

**Return Value: This method returns an iterator over the elements in this set in descending order.
Below are the examples to illustrate the _descendingIterator() method
**Example 1:

Java `

// Java program to demonstrate // descendingIterator() method // for Integer value

import java.util.*;

public class GFG1 { public static void main(String[] argv) throws Exception { try {

        // create tree set object
        TreeSet<Integer> treeadd = new TreeSet<Integer>();

        // populate the TreeSet using add() method
        treeadd.add(10);
        treeadd.add(20);
        treeadd.add(30);
        treeadd.add(40);

        // Print the TreeSet
        System.out.println("TreeSet: " + treeadd);

        // create descending iterator
        // using descendingIterator() method
        Iterator<Integer>
            iterator = treeadd.descendingIterator();

        System.out.println("\nValues using DescendingIterator:");

        // printing the integrated value
        while (iterator.hasNext()) {
            System.out.println("Value : "
                               + iterator.next());
        }
    }

    catch (NullPointerException e) {
        System.out.println("Exception thrown : " + e);
    }
}

}

`

Output

TreeSet: [10, 20, 30, 40]

Values using DescendingIterator: Value : 40 Value : 30 Value : 20 Value : 10

**Example 2:

Java `

// Java program to demonstrate // descendingIterator() method // for String value

import java.util.*;

public class GFG1 { public static void main(String[] argv) throws Exception { try {

        // create tree set object
        TreeSet<String> treeadd = new TreeSet<String>();

        // populate the TreeSet using add() method
        treeadd.add("A");
        treeadd.add("B");
        treeadd.add("C");
        treeadd.add("D");

        // Print the TreeSet
        System.out.println("TreeSet: " + treeadd);

        // create descending iterator
        // using descendingIterator() method
        Iterator<String>
            iterator = treeadd.descendingIterator();

        System.out.println("\nValues using DescendingIterator:");

        // printing the integrated value
        while (iterator.hasNext()) {
            System.out.println("Value : "
                               + iterator.next());
        }
    }

    catch (Exception e) {
        System.out.println("Exception thrown : " + e);
    }
}

}

`

Output

TreeSet: [A, B, C, D]

Values using DescendingIterator: Value : D Value : C Value : B Value : A