When should i use interface in java ?? And what is the benefit of it ?(deep answer plz)

Answer 1

When we should use it:
https://stackoverflow.com/questions/2586389/when-should-i-use-an-interface-in-java

Advantages:
https://stackoverflow.com/questions/5835311/what-is-the-advantage-of-interface-over-abstract-classes

Answer 2

Also, this thread has good discussion:
https://www.sololearn.com/Discuss/837263/?ref=app