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AscendingNameComparator.java

import java.util.Comparator;

public class AscendingNameComparator implements Comparator<String>
{

    /*
     * This method used to arrange the names in ascending order.
     */
    @Override
    public int compare( String name1, String name2 )
    {

        return name1.compareTo(name2);
    }

}

import java.util.Comparator;
import java.util.TreeSet;

/*
 * Example of comparator() method.
 */
public class TreeSetExample
{
    public static void main( String[] args )
    {

        AscendingNameComparator ascendingNameComparator = new AscendingNameComparator();
        
        TreeSet<String> treeSet = new TreeSet<String>(ascendingNameComparator);

        treeSet.add("Balu");
        treeSet.add("Ajay");
        treeSet.add("David");
        treeSet.add("Charles");

        /*
         * Returns the comparator used to order the elements in this set, or
         * null if this set uses the natural ordering of its elements.
         */

        Comparator<?> comparator = treeSet.comparator();

        System.out.println("comparator used : "
                + comparator.getClass().getName());

    }
}