Java Collection: HashSet

It is a specialized implementation of the Set interface. It uses the concept of HashTable in Data Structure.

A few important facts about HashSet are as follows:

1. It is synchronized.
2. It does not allow duplicate values.
3. It allows null values.
4. Element retrieval order is not the same as insertion.

---

Hierarchy of HashSet class

---

It extends AbstractSet and implements Set, Clonable, and Serializable interfaces in Java.

Source code of Item.java

package com.t4b.test; public class Item { String name; int id; double price; public Item(String name, int id, double price) { super(); this.name = name; this.id = id; this.price = price; } @Override public String toString() { return "Item [name=" + name + ", id=" + id + ", price=" + price + "]"; } }

Source code of TestMain.java

package com.t4b.test; import java.util.HashSet; import java.util.Iterator; public class TestMain { public static void main(String[] args) { HashSet<Item> hashset = new HashSet<Item>(); hashset.add(new Item("Apple", 1, 150.0)); hashset.add(new Item("Grape", 2, 250.0)); hashset.add(new Item("Mango", 3, 10)); hashset.add(new Item("Pine Apple", 4, 100)); Iterator<Item> itr = hashset.iterator(); while (itr.hasNext()) { System.out.println(itr.next()); } } }

Happy Exploring!