How HashSet works internally in Java

Hello Friends,

In this tutorial,we will see how java.util.HashSet works internally.

I would strongly recommend anybody reading this tutorial to read first How HashMap works Internally in java

HashSet is backed by a HashMap.What this statement means is that whenever we create instance of HashSet,an instance of HashMap is created in background.

HashSet class has reference variable of HashMap class as instance variable,which is declared as below

private transient HashMap<E,Object> map;

So basically whenever we instantiate HashSet using any of it's constructor,this map will be instantiated with HashMap object.