why does a.hashset = b.hashset code example

Example 1: hashset in java

// iterate hashset in java
import java.util.HashSet;
public class HashSetForEach 
{
   public static void main(String[] args) 
   {
      HashSet<String> hs = new HashSet<String>();
      hs.add("Hello"); 
      hs.add("world"); 
      hs.add("Java"); 
      for(String str : hs)
      {
         System.out.println(str);
      }
   }
}

Example 2: hashset in java

// java hashmap example
import java.util.HashMap;
public class HashMapExample 
{
   public static void main(String[] args) 
   {
      HashMap<Integer, String> hm = new HashMap<Integer, String>();
      // add elements
      hm.put(10,"Apple");
      hm.put(20,"Banana");
      hm.put(30,"Cherry");
      hm.put(40,"Dragonfruit");
      // print HashMap elements
      System.out.println("HashMap elements: " + hm);
   }
}