Create unique lists of items

This example shows how to remove duplicate elements from a list object.

import java.util.ArrayList;
import java.util.HashSet;
import java.util.Set;

public class CreateUniqueList {
	public static void main(String[] args) {

		/** Create a ArrayList object **/

		ArrayList< string > arrayList = new ArrayList< string >();

		/** Add elements to ArrayList.ArrayList occupies duplicate elements. **/

		arrayList.add("A");
		arrayList.add("B");
		arrayList.add("C");
		arrayList.add("D");
		arrayList.add("A");

		/**
		 * HashSet(Collection c) - Constructs a new set containing the unique
		 * elements in the specified collection. A set is a collection object
		 * that cannot have a duplicate values, so by converting the list to a
		 * set the duplicate value will be removed.
		 **/

		Set set = new HashSet(arrayList);

		System.out.println("The set contains..." + set);

	}
}

The output is:

The set contains...[D, A, B, C]