Java Collections: HashSet Example

• HashSet is a good choice for representing sets if order of the elements is not important
• HashSet methods are not synchronized
• HashSet not allowing duplicate elements

 

Example

package mycollectiontest;

import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

public class CollectionExample {

   public static void main(String[] args) {
      Set<String> set = new HashSet<String>();
      set.add("Bangalore");
      set.add("Chennai");
      set.add("Mumbai");
      set.add("Hydrabad");
      // Printing set
      System.out.println(set);
      // Iterating and set
      Iterator<String> it = set.iterator();
      while (it.hasNext()) {
         System.out.println("Elements " + it.next());
      }

      // Trying to add duplicate;
      set.add("Bangalore");
      System.out.println(set);
   }

}

Output

[Chennai, Hydrabad, Mumbai, Bangalore]
Elements Chennai
Elements Hydrabad
Elements Mumbai
Elements Bangalore
[Chennai, Hydrabad, Mumbai, Bangalore]