Java collection hierarchy and some sample code

The following is some example code to illustrate some collection:

import java.util.*;
 
public class CollectionsDemo {
 
 public static void main(String[] args) {
  List a1 = new ArrayList();
  a1.add(”Beginner”);
  a1.add(”Java”);
  a1.add(”tutorial”);
  System.out.println(” ArrayList Elements”);
  System.out.print(”\t” + a1);
  List l1 = new LinkedList();
  l1.add(”Beginner”);
  l1.add(”Java”);
  l1.add(”tutorial”);
  System.out.println();
  System.out.println(” LinkedList Elements”);
  System.out.print(”\t” + l1);
  Set s1 = new HashSet(); // or new TreeSet() will order the elements;
  s1.add(”Beginner”);
  s1.add(”Java”);
  s1.add(”Java”);
  s1.add(”tutorial”);
  System.out.println();
  System.out.println(” Set Elements”);
  System.out.print(”\t” + s1);
  Map m1 = new HashMap(); // or new TreeMap() will order based on keys
  m1.put(”Windows”, “98″);
  m1.put(”Win”, “XP”);
  m1.put(”Beginner”, “Java”);
  m1.put(”Tutorial”, “Site”);
  System.out.println();
  System.out.println(” Map Elements”);
  System.out.print(”\t” + m1);
 }
}

output: 

ArrayList Elements
[Beginner, Java, tutorial]
LinkedList Elements
[Beginner, Java, tutorial]
Set Elements
[tutorial, Beginner, Java]
Map Elements
{Tutorial=Site, Windows=98, Win=XP, Beginner=Java}