hash code

[video]

HashCode and its purpose
https://www.youtube.com/watch?v=HFoQEyxKDhQ

equals() and hashCode() in Java with an Example
https://www.youtube.com/watch?v=fAlRR2p9Le0

hashcode equals method java interview question and answer
https://www.youtube.com/watch?v=nkvdRrliOFc

Difference between == and equals method in JAVA
https://www.youtube.com/watch?v=WTOiuY7cNTo