What is the difference between 'open' and 'public' in Kotlin?

Question

I am new to Kotlin and I am confused between open and public keywords. Could anyone please tell me the difference between those keywords?

Answer 1

open is opposite to Final in java. If the class is not 'open', it can't be inherited.

class First{}
class Second:First(){}  // Not allowed. Since 'First' is Final(as in Java) by default. Unless marked "open" it can't be inherited 

Don't get confused with open and public. public is a visibility modifier

class Third{}  // By default this is public
private class Fourth{}
class Fifth{
    val third = Third() // No issues
    val fourth = Fourth() // Can't access because Fourth is private
}