What is interface in java ?

Question

Its types

Answer 1

interface is a reference type in Java. It is similar to class.

But please use the search bar before posting question here
https://www.sololearn.com/discuss/43857/?ref=app
https://www.sololearn.com/discuss/2074424/?ref=app
https://www.sololearn.com/discuss/1384430/?ref=app
https://www.sololearn.com/discuss/1474680/?ref=app

Answer 2

There are two very common types of interfaces that I have heard of are:
1) functional interface - only 1 method
2) marker interface - no methods